Camshaft Selection
12-10-2017, 10:55 AM
#1
Racer
Thread Starter
Camshaft Selection
I'm building a new engine for my 61, and need some advice on parts, especially the camshaft. I'm trying to keep it as original looking as possible. I'd like to see 325-350 RWHP. Car gets driven a few thousand miles a year, cruising, squirreling around and occasional weekend trip.
The current build specs so far are....
1969 3959512 SJ 327 Block, It has been bored .060", aligned and decked.(It has the draft tube holes)
Forged 1182 3.48" stroke crank ground to SJ
Trick Flow DHC 175 heads, flow is 255/198@.500"
Forged 6-10cc pistons, final size will be sized on a final 8.5-8.7:1 DCR
Quench will be in the .035-.041" range
Edelbrock C26 2x4 manifold with Edelbrock carbs
Car will have a TKO600 2.87/.82 with 3.70 rear
I'm still on the fence about cams. I was originally thinking a hydraulic roller something like XR276HR or XR282HR from Comp. But after playing with Desktop Dyno for a few days, I like the power curves of the solid rollers like a XR268R or XR274R. Less duration and more lift preserves the low end while giving a better top end. I'm also looking at similar cams from Howards and Lunati.
Anyone run one of those cams, and have input on the balance of low end torque vs high rpm hp. Looking for a good balance between the two. It's not a race car, but I may take it to the track occasionally.
I guess the main question is how much luck anyone has had at making a solid roller last for limited street driving. It won't see much idling in traffic, but it will see some. Adjusting it a time or two a year isn't a big deal. But I don't want to have the lifters rebuilt every year or so. I would be running pressurized lifters and a rev kit to promote lifter longevity.
The current build specs so far are....
1969 3959512 SJ 327 Block, It has been bored .060", aligned and decked.(It has the draft tube holes)
Forged 1182 3.48" stroke crank ground to SJ
Trick Flow DHC 175 heads, flow is 255/198@.500"
Forged 6-10cc pistons, final size will be sized on a final 8.5-8.7:1 DCR
Quench will be in the .035-.041" range
Edelbrock C26 2x4 manifold with Edelbrock carbs
Car will have a TKO600 2.87/.82 with 3.70 rear
I'm still on the fence about cams. I was originally thinking a hydraulic roller something like XR276HR or XR282HR from Comp. But after playing with Desktop Dyno for a few days, I like the power curves of the solid rollers like a XR268R or XR274R. Less duration and more lift preserves the low end while giving a better top end. I'm also looking at similar cams from Howards and Lunati.
Anyone run one of those cams, and have input on the balance of low end torque vs high rpm hp. Looking for a good balance between the two. It's not a race car, but I may take it to the track occasionally.
I guess the main question is how much luck anyone has had at making a solid roller last for limited street driving. It won't see much idling in traffic, but it will see some. Adjusting it a time or two a year isn't a big deal. But I don't want to have the lifters rebuilt every year or so. I would be running pressurized lifters and a rev kit to promote lifter longevity.
12-10-2017, 11:01 AM
#2
Team Owner
Member Since: Feb 2003
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2015 C2 of Year Finalist
I would go with a OEM grind from Sealed power of either a L79 or LT-1 style your get good Street manors and driverablity
12-10-2017, 11:18 AM
#3
Strongly recommend the retro hyd-roller platform.
Just changing to the roller yields some 30 (nominal) "free" HP.
We have now done "tons" of these 100% stock-appearing SBC builds for a number of local recsto shops in the area! All get dynoed!
We now do 95% of these early SBC roller retro's with a cam thrust plate and 2 mounting screws, absolutely no more cam buttons or chasing end play!! OEM timing covers work fine! Photo below.
If you do go mech-roller on the street I would use ONLY the bushed roller lifters, no more needle-brgs here!
Thanks, Gary in N.Y.
P.S. We use the late style (1996) stepped-nose cam from Comp, possibly in your case a #08-466-8, uses all the factory components (dist gear, f/p pushrod, etc). This is 113* LS cam, .570" x .565" lifts!
Just changing to the roller yields some 30 (nominal) "free" HP.
We have now done "tons" of these 100% stock-appearing SBC builds for a number of local recsto shops in the area! All get dynoed!
We now do 95% of these early SBC roller retro's with a cam thrust plate and 2 mounting screws, absolutely no more cam buttons or chasing end play!! OEM timing covers work fine! Photo below.
If you do go mech-roller on the street I would use ONLY the bushed roller lifters, no more needle-brgs here!
Thanks, Gary in N.Y.
P.S. We use the late style (1996) stepped-nose cam from Comp, possibly in your case a #08-466-8, uses all the factory components (dist gear, f/p pushrod, etc). This is 113* LS cam, .570" x .565" lifts!
Last edited by GOSFAST; 12-10-2017 at 11:19 AM. Reason: C
12-10-2017, 12:22 PM
#4
Racer
Thread Starter
Looking for something like that, just in roller. Similar duration, .100" more lift. Close to the same drivability, more power.
Strongly recommend the retro hyd-roller platform.
Just changing to the roller yields some 30 (nominal) "free" HP.
We have now done "tons" of these 100% stock-appearing SBC builds for a number of local recsto shops in the area! All get dynoed!
We now do 95% of these early SBC roller retro's with a cam thrust plate and 2 mounting screws, absolutely no more cam buttons or chasing end play!! OEM timing covers work fine! Photo below.
If you do go mech-roller on the street I would use ONLY the bushed roller lifters, no more needle-brgs here!
Thanks, Gary in N.Y.
P.S. We use the late style (1996) stepped-nose cam from Comp, possibly in your case a #08-466-8, uses all the factory components (dist gear, f/p pushrod, etc). This is 113* LS cam, .570" x .565" lifts!
Just changing to the roller yields some 30 (nominal) "free" HP.
We have now done "tons" of these 100% stock-appearing SBC builds for a number of local recsto shops in the area! All get dynoed!
We now do 95% of these early SBC roller retro's with a cam thrust plate and 2 mounting screws, absolutely no more cam buttons or chasing end play!! OEM timing covers work fine! Photo below.
If you do go mech-roller on the street I would use ONLY the bushed roller lifters, no more needle-brgs here!
Thanks, Gary in N.Y.
P.S. We use the late style (1996) stepped-nose cam from Comp, possibly in your case a #08-466-8, uses all the factory components (dist gear, f/p pushrod, etc). This is 113* LS cam, .570" x .565" lifts!
I'd much prefer a plate to a button. What machining does it take to mount the thrust plate to the old block? Standard step nose cam work with it?
I'd prefer a bushed roller too, but the bushed ones run ~$400 more for the same lifter. Probably cost less to build it with the bushing too. I guess I's save a few bucks on a rev kit.
Probably end up with a hydraulic roller, but I sure like the sound of a solid one.
12-10-2017, 03:08 PM
#5
Looking for something like that, just in roller. Similar duration, .100" more lift. Close to the same drivability, more power.
I'd much prefer a plate to a button. What machining does it take to mount the thrust plate to the old block? Standard step nose cam work with it?
I'd much prefer a plate to a button. What machining does it take to mount the thrust plate to the old block? Standard step nose cam work with it?
After a number of my own customers started asking to do their blocks we figured we'd put together the tooling in a package and sell it the outside world. So far it's been very successful? Here's another shot with the cam in the block. We also use "Torrington" brg timing sets for these later cams!
You will need a floor-model drill press that will support the block on it's rear, this is the only shop-like tool needed! Takes us about 20 minutes to do one here.
Thanks, Gary in N.Y.
P.S. This setup allows either roller cam to used, hyd or mech! The complete tooling for the mod runs $150.00 and comes with the first plate/screws! We stock the plates and screws at all times, have at least 100 or so (pre-drilled) in stock! We also use "Tru-Roller"/ "Torrington" brg timing sets (not pictured, that is a stock cam gear) for these builds
12-10-2017, 03:37 PM
#6
Le Mans Master
Member Since: Nov 2003
Location: Maryland
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St. Jude Donor '05, '09, '15
Strongly recommend the retro hyd-roller platform.
Just changing to the roller yields some 30 (nominal) "free" HP.
We have now done "tons" of these 100% stock-appearing SBC builds for a number of local recsto shops in the area! All get dynoed!
Thanks, Gary in N.Y.
P.S. We use the late style (1996) stepped-nose cam from Comp, possibly in your case a #08-466-8, uses all the factory components (dist gear, f/p pushrod, etc). This is 113* LS cam, .570" x .565" lifts!
Just changing to the roller yields some 30 (nominal) "free" HP.
We have now done "tons" of these 100% stock-appearing SBC builds for a number of local recsto shops in the area! All get dynoed!
Thanks, Gary in N.Y.
P.S. We use the late style (1996) stepped-nose cam from Comp, possibly in your case a #08-466-8, uses all the factory components (dist gear, f/p pushrod, etc). This is 113* LS cam, .570" x .565" lifts!
Thanks
Tom
Last edited by Sky65; 12-10-2017 at 03:38 PM.
12-10-2017, 10:38 PM
#7
Drifting
I'm building a new engine for my 61, and need some advice on parts, especially the camshaft. I'm trying to keep it as original looking as possible. I'd like to see 325-350 RWHP. Car gets driven a few thousand miles a year, cruising, squirreling around and occasional weekend trip.
The current build specs so far are....
1969 3959512 SJ 327 Block, It has been bored .060", aligned and decked.(It has the draft tube holes)
Forged 1182 3.48" stroke crank ground to SJ
Trick Flow DHC 175 heads, flow is 255/198@.500"
Forged 6-10cc pistons, final size will be sized on a final 8.5-8.7:1 DCR
Quench will be in the .035-.041" range
Edelbrock C26 2x4 manifold with Edelbrock carbs
Car will have a TKO600 2.87/.82 with 3.70 rear
I'm still on the fence about cams. I was originally thinking a hydraulic roller something like XR276HR or XR282HR from Comp. But after playing with Desktop Dyno for a few days, I like the power curves of the solid rollers like a XR268R or XR274R. Less duration and more lift preserves the low end while giving a better top end. I'm also looking at similar cams from Howards and Lunati.
Anyone run one of those cams, and have input on the balance of low end torque vs high rpm hp. Looking for a good balance between the two. It's not a race car, but I may take it to the track occasionally.
I guess the main question is how much luck anyone has had at making a solid roller last for limited street driving. It won't see much idling in traffic, but it will see some. Adjusting it a time or two a year isn't a big deal. But I don't want to have the lifters rebuilt every year or so. I would be running pressurized lifters and a rev kit to promote lifter longevity.
The current build specs so far are....
1969 3959512 SJ 327 Block, It has been bored .060", aligned and decked.(It has the draft tube holes)
Forged 1182 3.48" stroke crank ground to SJ
Trick Flow DHC 175 heads, flow is 255/198@.500"
Forged 6-10cc pistons, final size will be sized on a final 8.5-8.7:1 DCR
Quench will be in the .035-.041" range
Edelbrock C26 2x4 manifold with Edelbrock carbs
Car will have a TKO600 2.87/.82 with 3.70 rear
I'm still on the fence about cams. I was originally thinking a hydraulic roller something like XR276HR or XR282HR from Comp. But after playing with Desktop Dyno for a few days, I like the power curves of the solid rollers like a XR268R or XR274R. Less duration and more lift preserves the low end while giving a better top end. I'm also looking at similar cams from Howards and Lunati.
Anyone run one of those cams, and have input on the balance of low end torque vs high rpm hp. Looking for a good balance between the two. It's not a race car, but I may take it to the track occasionally.
I guess the main question is how much luck anyone has had at making a solid roller last for limited street driving. It won't see much idling in traffic, but it will see some. Adjusting it a time or two a year isn't a big deal. But I don't want to have the lifters rebuilt every year or so. I would be running pressurized lifters and a rev kit to promote lifter longevity.
For a 383 that I recently built, I used the Comp Cams hydraulic roller 280HR. While the L79 cam has 222/222 duration with .447 lift, the 280HR has 224/224 duration with .525 lift. The LSA of the L79 is 114 degrees, while the LSA of the 280HR is 110 degrees.
My 383 seems to tolerate the extra overlap pretty well, but for your 350 you might consider getting a custom version of the 280HR with the LSA at 112 degrees. In a 350, that would likely give you idle characteristics very similar to the L79 in a 327.
BTW, the Dart heads on my 383 have similar flow to your Trick Flow heads, SCR is 10.2, DCR is about 8.0, transmission is a TKO 600 with the same gear set that you have, and the rear is a 3.70, same as yours.
This combination runs very strong and is a lot of fun on the street. My only regret is that I did not get the .64 overdrive in the TKO 600 (I got the 0.82 that you mention). My TKO gear set was selected back when I was running a 327.
My 383 would have no trouble whatsoever with the .64 overdrive, especially with the 3.70 rear. Unless you go really radical with your cam, I think the 350 would also be fine with the 0.64 overdrive.
BTW, if you haven't yet committed to the crank and pistons, that '512 block you have can be easily expanded to a 383.
Last edited by GearheadJoe; 12-10-2017 at 10:39 PM. Reason: Clarification
12-10-2017, 11:03 PM
#8
Le Mans Master
Member Since: Nov 2003
Location: Maryland
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St. Jude Donor '05, '09, '15
In terms of OEM cams for all-around street use, I'm a big fan of the L79 cam. However, I also like the performance benefits that roller cams offer in terms of more lift for a given duration.
For a 383 that I recently built, I used the Comp Cams hydraulic roller 280HR. While the L79 cam has 222/222 duration with .447 lift, the 280HR has 224/224 duration with .525 lift. The LSA of the L79 is 114 degrees, while the LSA of the 280HR is 110 degrees.
My 383 seems to tolerate the extra overlap pretty well, but for your 350 you might consider getting a custom version of the 280HR with the LSA at 112 degrees. In a 350, that would likely give you idle characteristics very similar to the L79 in a 327.
BTW, the Dart heads on my 383 have similar flow to your Trick Flow heads, SCR is 10.2, DCR is about 8.0, transmission is a TKO 600 with the same gear set that you have, and the rear is a 3.70, same as yours.
This combination runs very strong and is a lot of fun on the street. My only regret is that I did not get the .64 overdrive in the TKO 600 (I got the 0.82 that you mention). My TKO gear set was selected back when I was running a 327.
My 383 would have no trouble whatsoever with the .64 overdrive, especially with the 3.70 rear. Unless you go really radical with your cam, I think the 350 would also be fine with the 0.64 overdrive.
BTW, if you haven't yet committed to the crank and pistons, that '512 block you have can be easily expanded to a 383.
For a 383 that I recently built, I used the Comp Cams hydraulic roller 280HR. While the L79 cam has 222/222 duration with .447 lift, the 280HR has 224/224 duration with .525 lift. The LSA of the L79 is 114 degrees, while the LSA of the 280HR is 110 degrees.
My 383 seems to tolerate the extra overlap pretty well, but for your 350 you might consider getting a custom version of the 280HR with the LSA at 112 degrees. In a 350, that would likely give you idle characteristics very similar to the L79 in a 327.
BTW, the Dart heads on my 383 have similar flow to your Trick Flow heads, SCR is 10.2, DCR is about 8.0, transmission is a TKO 600 with the same gear set that you have, and the rear is a 3.70, same as yours.
This combination runs very strong and is a lot of fun on the street. My only regret is that I did not get the .64 overdrive in the TKO 600 (I got the 0.82 that you mention). My TKO gear set was selected back when I was running a 327.
My 383 would have no trouble whatsoever with the .64 overdrive, especially with the 3.70 rear. Unless you go really radical with your cam, I think the 350 would also be fine with the 0.64 overdrive.
BTW, if you haven't yet committed to the crank and pistons, that '512 block you have can be easily expanded to a 383.
Tom
12-10-2017, 11:13 PM
#9
I would consider the LT-1 cam. It was designed for the 350. It offers OEM reliability and makes great torque. With a six speed trans, I would be tempted to use the 30-30.
Since you are using an aftermarket head, you can make up some power with a very good set of heads. Save elsewhere and spend big here.
I would ditch the 2X4 intake in favor of a single Holley, but that is my opinion, and this is your build.
Since you are using an aftermarket head, you can make up some power with a very good set of heads. Save elsewhere and spend big here.
I would ditch the 2X4 intake in favor of a single Holley, but that is my opinion, and this is your build.
Last edited by ghostrider20; 12-10-2017 at 11:19 PM.
12-12-2017, 07:09 AM
#11
Racer
Thread Starter
Like some of you, I wish that the TKO600 had a .7-.75 OD. I have a lot of secondary roads that I run 60-65 mph and the .64 is just too high. If the .82/3.70 doesn't work for me, I have a 3.36 ring and pinion I can swap in. It would be like a 4.30-ish 1st gear with a 2.75 final drive. That should be about perfect gearing for the car. I gave some thought to a T56, but just can't find much info on the installation. Anybody know what the required tunnel mods are?
I know I can make more power with better heads and intake. Just trying to keep looking as original as possible. But I do have a Performer and 750 DP that I'll probably swap in occasionally.
I'm pretty much ruling out the solid rollers, due to $1000 for the bushed lifters. I like the L79 and 30-30 cam, but want the added power from a roller. Right now I'm leaning toward the Howards 110325-10. Specs are....
278/286 225/233@.50" .525"/.530" 110/106
Specs are between the L79 and 30-30. And with the intake closing at 65 ABDC, I can use flat top pistons with the 60cc heads. Should be good for the street, have a decent lope, and be good for 400-425hp. Any thoughts?
That brings me to an interesting decision on head gasket thicknesses too. Considering aluminum heads with heart shaped 60cc CNC chambers and flat top pistons, which would be the best choice for quench/DCR ??? This is based on .030", .036" and .039" gaskets. Pistons would be .005" in the hole.
.044" quench 8.54 DCR
.041" quench 8.60 DCR
.035" quench 8.74 DCR
I know I can make more power with better heads and intake. Just trying to keep looking as original as possible. But I do have a Performer and 750 DP that I'll probably swap in occasionally.
I'm pretty much ruling out the solid rollers, due to $1000 for the bushed lifters. I like the L79 and 30-30 cam, but want the added power from a roller. Right now I'm leaning toward the Howards 110325-10. Specs are....
278/286 225/233@.50" .525"/.530" 110/106
Specs are between the L79 and 30-30. And with the intake closing at 65 ABDC, I can use flat top pistons with the 60cc heads. Should be good for the street, have a decent lope, and be good for 400-425hp. Any thoughts?
That brings me to an interesting decision on head gasket thicknesses too. Considering aluminum heads with heart shaped 60cc CNC chambers and flat top pistons, which would be the best choice for quench/DCR ??? This is based on .030", .036" and .039" gaskets. Pistons would be .005" in the hole.
.044" quench 8.54 DCR
.041" quench 8.60 DCR
.035" quench 8.74 DCR
12-12-2017, 10:03 AM
#12
Safety Car
I'm building a new engine for my 61, and need some advice on parts, especially the camshaft. I'm trying to keep it as original looking as possible. I'd like to see 325-350 RWHP. Car gets driven a few thousand miles a year, cruising, squirreling around and occasional weekend trip.
The current build specs so far are....
1969 3959512 SJ 327 Block, It has been bored .060", aligned and decked.(It has the draft tube holes)
Forged 1182 3.48" stroke crank ground to SJ
Trick Flow DHC 175 heads, flow is 255/198@.500"
Forged 6-10cc pistons, final size will be sized on a final 8.5-8.7:1 DCR
Quench will be in the .035-.041" range
Edelbrock C26 2x4 manifold with Edelbrock carbs
Car will have a TKO600 2.87/.82 with 3.70 rear
I'm still on the fence about cams. I was originally thinking a hydraulic roller something like XR276HR or XR282HR from Comp. But after playing with Desktop Dyno for a few days, I like the power curves of the solid rollers like a XR268R or XR274R. Less duration and more lift preserves the low end while giving a better top end. I'm also looking at similar cams from Howards and Lunati.
Anyone run one of those cams, and have input on the balance of low end torque vs high rpm hp. Looking for a good balance between the two. It's not a race car, but I may take it to the track occasionally.
I guess the main question is how much luck anyone has had at making a solid roller last for limited street driving. It won't see much idling in traffic, but it will see some. Adjusting it a time or two a year isn't a big deal. But I don't want to have the lifters rebuilt every year or so. I would be running pressurized lifters and a rev kit to promote lifter longevity.
The current build specs so far are....
1969 3959512 SJ 327 Block, It has been bored .060", aligned and decked.(It has the draft tube holes)
Forged 1182 3.48" stroke crank ground to SJ
Trick Flow DHC 175 heads, flow is 255/198@.500"
Forged 6-10cc pistons, final size will be sized on a final 8.5-8.7:1 DCR
Quench will be in the .035-.041" range
Edelbrock C26 2x4 manifold with Edelbrock carbs
Car will have a TKO600 2.87/.82 with 3.70 rear
I'm still on the fence about cams. I was originally thinking a hydraulic roller something like XR276HR or XR282HR from Comp. But after playing with Desktop Dyno for a few days, I like the power curves of the solid rollers like a XR268R or XR274R. Less duration and more lift preserves the low end while giving a better top end. I'm also looking at similar cams from Howards and Lunati.
Anyone run one of those cams, and have input on the balance of low end torque vs high rpm hp. Looking for a good balance between the two. It's not a race car, but I may take it to the track occasionally.
I guess the main question is how much luck anyone has had at making a solid roller last for limited street driving. It won't see much idling in traffic, but it will see some. Adjusting it a time or two a year isn't a big deal. But I don't want to have the lifters rebuilt every year or so. I would be running pressurized lifters and a rev kit to promote lifter longevity.
Below is what you might want to see. Expect a flatter torque curve with a smaller cam, of course. My heads are 203cc, so expect a correspondingly lower but flatter torque curve with your build. I run 11.6:1 static with about 8.7 DCR and .035 quench. Good luck.
One more thing...............you should use a 1.5 rocker with your heads. The extra lift from the 1.6 will be basically wasted on yours. And you will also have to change your distributor drive gear to a melonized steel one. This cam is not compatible with the original, iron gear. Neither are the hydraulic rollers.
Last edited by 65tripleblack; 12-12-2017 at 10:17 AM.
The following users liked this post:
Drothgeb (12-12-2017)
12-12-2017, 10:22 AM
#13
Le Mans Master
Member Since: Nov 2003
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St. Jude Donor '05, '09, '15
Like some of you, I wish that the TKO600 had a .7-.75 OD. I have a lot of secondary roads that I run 60-65 mph and the .64 is just too high. If the .82/3.70 doesn't work for me, I have a 3.36 ring and pinion I can swap in. It would be like a 4.30-ish 1st gear with a 2.75 final drive. That should be about perfect gearing for the car. I gave some thought to a T56, but just can't find much info on the installation. Anybody know what the required tunnel mods are?
I know I can make more power with better heads and intake. Just trying to keep looking as original as possible. But I do have a Performer and 750 DP that I'll probably swap in occasionally.
I'm pretty much ruling out the solid rollers, due to $1000 for the bushed lifters. I like the L79 and 30-30 cam, but want the added power from a roller. Right now I'm leaning toward the Howards 110325-10. Specs are....
278/286 225/233@.50" .525"/.530" 110/106
Specs are between the L79 and 30-30. And with the intake closing at 65 ABDC, I can use flat top pistons with the 60cc heads. Should be good for the street, have a decent lope, and be good for 400-425hp. Any thoughts?
That brings me to an interesting decision on head gasket thicknesses too. Considering aluminum heads with heart shaped 60cc CNC chambers and flat top pistons, which would be the best choice for quench/DCR ??? This is based on .030", .036" and .039" gaskets. Pistons would be .005" in the hole.
.044" quench 8.54 DCR
.041" quench 8.60 DCR
.035" quench 8.74 DCR
I know I can make more power with better heads and intake. Just trying to keep looking as original as possible. But I do have a Performer and 750 DP that I'll probably swap in occasionally.
I'm pretty much ruling out the solid rollers, due to $1000 for the bushed lifters. I like the L79 and 30-30 cam, but want the added power from a roller. Right now I'm leaning toward the Howards 110325-10. Specs are....
278/286 225/233@.50" .525"/.530" 110/106
Specs are between the L79 and 30-30. And with the intake closing at 65 ABDC, I can use flat top pistons with the 60cc heads. Should be good for the street, have a decent lope, and be good for 400-425hp. Any thoughts?
That brings me to an interesting decision on head gasket thicknesses too. Considering aluminum heads with heart shaped 60cc CNC chambers and flat top pistons, which would be the best choice for quench/DCR ??? This is based on .030", .036" and .039" gaskets. Pistons would be .005" in the hole.
.044" quench 8.54 DCR
.041" quench 8.60 DCR
.035" quench 8.74 DCR
Tom
12-12-2017, 06:55 PM
#14
Team Owner
Member Since: Nov 2005
Location: Beach & High Desert Southern California
Posts: 25,500
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Looking for something like that, just in roller. Similar duration, .100" more lift. Close to the same drivability, more power.
I'd much prefer a plate to a button. What machining does it take to mount the thrust plate to the old block? Standard step nose cam work with it?
I'd prefer a bushed roller too, but the bushed ones run ~$400 more for the same lifter. Probably cost less to build it with the bushing too. I guess I's save a few bucks on a rev kit.
Probably end up with a hydraulic roller, but I sure like the sound of a solid one.
I'd much prefer a plate to a button. What machining does it take to mount the thrust plate to the old block? Standard step nose cam work with it?
I'd prefer a bushed roller too, but the bushed ones run ~$400 more for the same lifter. Probably cost less to build it with the bushing too. I guess I's save a few bucks on a rev kit.
Probably end up with a hydraulic roller, but I sure like the sound of a solid one.
http://www.iskycams.com/tech-tips-2000.html
Intake Restriction and Over Scavenging: "Waste not...Want not!"
It is certainly an over simplification to make the statement "that which is not wasted, should be inducted". However, in the case of restricted intake systems and in particular 2-BBL carb rules, it is not far off the mark. Engines with such restrictions are "choked off" to the point where they will not run much past 6500 RPM (if even that high) without dropping off sharply in power. You might have trouble running very fast yourself if someone had your windpipe choked down to say 50 or 60% of it's normal capacity. Under such conditions, would you volunteer to give blood at the Red Cross? Of course not, but without knowing so, racers often do the equivalent with their engines by running a camshaft better suited for a 4-BBL class! How So?
If you'll recall in last months tech tip: "Longer Exhaust Duration: Is This Really Necessary?" I discussed how, through habit, many racers and cam grinders alike are predisposed to running camshafts with longer exhaust durations, whether they need to or not! Well, in the case of restricted intake applications, if there was ever a situation in which you'd want to avoid the longer exhaust "trap" it's here! Especially the 8, 10, 12 or even longer degree spreads, I often discover people employing.
Use such a cam at you own risk - and don't be surprised to find that your exhaust temperatures are unusually high. Your headers in fact may even glow cherry red. There is a very good reason for this. Raw (unburned) fuel is burning "late" or in the pipe (header/manifold). You may have a good equilibrium of flow going here but there is just one problem. Much of what should be inducted into the cylinder is being scavenged out the exhaust! You see, although back pressure in an exhaust system can be restrictive, the only thing that could be even worse is a reduction of it to the point where you are now, in effect pulling a vacuum. In the case of an intake restriction, very slight back pressure is preferable to avoid "over scavenging".
Yes, Yes I know. You are probably thinking "what's wrong with a little scavenging?". Well, nothing if you can afford it. But with intake restrictions (either small 2-BBL carbs and/or restrictor plates) you must be very careful. You already have reduced intake potential and therefore simply cannot be cavalier about valve overlap and scavenging or you'll be way down on power and have those nice bright cherry red pipes to show for it! Case in Point: One racer who called me was in this exact situation and was running, not surprisingly, a 14 Degree longer exhaust duration. It was Friday afternoon and he needed a cam the next day for the last "points race" of the season and UPS had already picked up at Isky. "Too Bad" I said, "You don't have a set of those low ratio break-in rocker arms because they could really help in this case". " I do have some" he said "but they are only 1.2:1 ratio - is that okay?" I told him to use them (on his exhaust valves only of course) and he finished the race 2nd having come from the back of the pack. Later we made him the right cam so he could avoid this make shift approach.
Unfortunately, the symptoms are not always as obvious as in this case to allow for a speedy diagnosis. Also, it's not only longer exhaust duration that causes the problem. Although it is usually the primary offender, it is often coupled with too close a lobe separation angle of say 104 Degrees. A widening to 106 Degrees or preferably 108 Degrees (some go even wider) is usually prudent.
I am not absolutely dead set against a slightly longer exhaust duration in these cases as a 2-4 Degree longer exhaust lobe is permissible under some circumstances (if your running a completely stock exhaust system including mufflers for example). Each case is different, depending upon the equipment employed. I might even recommend shorter exhaust duration to some; if I feel they have "overdone" their exhaust ports and or exhaust system a bit. What matters is the end result and if you're out of balance on one side simply employ what I call the "Great Law of Compensation" to bring you back to that equilibrium of flow.
So, how can you tell if you may need to make some of these changes in your camshaft? Well, short of trying a lower exhaust rocker arm ratio, you can increase exhaust valve lash .004" - .008" temporarily to see if there is any improvement. You can also try and increase restriction (smaller headers or pipes, or in the case of open headers a longer collector) and simply observe the results. Remember, "One test is worth a thousand expert opinions". Keep this old axiom in your "tool box" and you'll be ahead of the game. How do you think Smokey's shop got to be "The best Damn Garage in Town" anyway? Yes, he had those country smarts, but his experiences in racing and his willingness to test are legendary!
Intake Restriction and Over Scavenging: "Waste not...Want not!"
It is certainly an over simplification to make the statement "that which is not wasted, should be inducted". However, in the case of restricted intake systems and in particular 2-BBL carb rules, it is not far off the mark. Engines with such restrictions are "choked off" to the point where they will not run much past 6500 RPM (if even that high) without dropping off sharply in power. You might have trouble running very fast yourself if someone had your windpipe choked down to say 50 or 60% of it's normal capacity. Under such conditions, would you volunteer to give blood at the Red Cross? Of course not, but without knowing so, racers often do the equivalent with their engines by running a camshaft better suited for a 4-BBL class! How So?
If you'll recall in last months tech tip: "Longer Exhaust Duration: Is This Really Necessary?" I discussed how, through habit, many racers and cam grinders alike are predisposed to running camshafts with longer exhaust durations, whether they need to or not! Well, in the case of restricted intake applications, if there was ever a situation in which you'd want to avoid the longer exhaust "trap" it's here! Especially the 8, 10, 12 or even longer degree spreads, I often discover people employing.
Use such a cam at you own risk - and don't be surprised to find that your exhaust temperatures are unusually high. Your headers in fact may even glow cherry red. There is a very good reason for this. Raw (unburned) fuel is burning "late" or in the pipe (header/manifold). You may have a good equilibrium of flow going here but there is just one problem. Much of what should be inducted into the cylinder is being scavenged out the exhaust! You see, although back pressure in an exhaust system can be restrictive, the only thing that could be even worse is a reduction of it to the point where you are now, in effect pulling a vacuum. In the case of an intake restriction, very slight back pressure is preferable to avoid "over scavenging".
Yes, Yes I know. You are probably thinking "what's wrong with a little scavenging?". Well, nothing if you can afford it. But with intake restrictions (either small 2-BBL carbs and/or restrictor plates) you must be very careful. You already have reduced intake potential and therefore simply cannot be cavalier about valve overlap and scavenging or you'll be way down on power and have those nice bright cherry red pipes to show for it! Case in Point: One racer who called me was in this exact situation and was running, not surprisingly, a 14 Degree longer exhaust duration. It was Friday afternoon and he needed a cam the next day for the last "points race" of the season and UPS had already picked up at Isky. "Too Bad" I said, "You don't have a set of those low ratio break-in rocker arms because they could really help in this case". " I do have some" he said "but they are only 1.2:1 ratio - is that okay?" I told him to use them (on his exhaust valves only of course) and he finished the race 2nd having come from the back of the pack. Later we made him the right cam so he could avoid this make shift approach.
Unfortunately, the symptoms are not always as obvious as in this case to allow for a speedy diagnosis. Also, it's not only longer exhaust duration that causes the problem. Although it is usually the primary offender, it is often coupled with too close a lobe separation angle of say 104 Degrees. A widening to 106 Degrees or preferably 108 Degrees (some go even wider) is usually prudent.
I am not absolutely dead set against a slightly longer exhaust duration in these cases as a 2-4 Degree longer exhaust lobe is permissible under some circumstances (if your running a completely stock exhaust system including mufflers for example). Each case is different, depending upon the equipment employed. I might even recommend shorter exhaust duration to some; if I feel they have "overdone" their exhaust ports and or exhaust system a bit. What matters is the end result and if you're out of balance on one side simply employ what I call the "Great Law of Compensation" to bring you back to that equilibrium of flow.
So, how can you tell if you may need to make some of these changes in your camshaft? Well, short of trying a lower exhaust rocker arm ratio, you can increase exhaust valve lash .004" - .008" temporarily to see if there is any improvement. You can also try and increase restriction (smaller headers or pipes, or in the case of open headers a longer collector) and simply observe the results. Remember, "One test is worth a thousand expert opinions". Keep this old axiom in your "tool box" and you'll be ahead of the game. How do you think Smokey's shop got to be "The best Damn Garage in Town" anyway? Yes, he had those country smarts, but his experiences in racing and his willingness to test are legendary!
My 357 build has a very aggressive solid flat lifter cam, matched to excellent flowing ported Bowtie heads and ported dual plane intake and exhaust manifolds. The intent was to focus on the mid-rpm torque with the somewhat less than ideal intake and exhaust, and have flexibility to unleash more top end with a swap to a single plane intake and headers. The cam uses lobe profiles from a stock short track application listing, but ground with a 4 degree wider lobe centerline (110 vs. the stock 106) to address the restrictions. Working directly with the cam grinder, with fine tuning to work with your build limitations, can deliver a better match than buying the cam off the shelf. I run the cam below with 1.6 intake rockers, and 1.5 exhaust rockers, a choice that is probably more radical than what will work best with your heads and intake. Work variations on the shelf spec cams in your program to model options beyond the catalog offerings.
The flywheel result (the tests below were with headers on the dyno) produces significant torque, and other than a weak spot past the torque peak (a carb issue that we think we worked out since) the hp exploits the solid lifters resistance to float at higher rpm. Ported exhaust manifolds and the undercar exhaust restriction with super-turbo mufflers cost me about 35 lbft of torque off these numbers and only lost about 20 peak hp.
You probably do not need to go past 6500 rpm, and a softer lobe profile is likely better with the low rpm matched to the OD (I seldom cruise below 3000 rpm, with 4.10 gears and the M20). The hydraulic rollers have more mass, and match my radical solid for torque and a longer expected life for a better build, as long as you don't need the high rpm. A milder solid flat lifter combination with 1.6 rockers is also likely to come closer to match your 2x4 intake and heads, and will get you 340-360 flywheel tq & hp (hitting your 300 RWHP target).
I still have the 0.622 lift solid roller cam and rev kit that I pulled from the engine (in it's prior build for a more race oriented car) before the last rebuild revision, and I am much happier with the manners of the solid flat. Everyone loves the radical build numbers, but few have to live with the results driving streets and highways (don't get lost in the numbers race, just make the best of what you have, and need).
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Drothgeb (12-13-2017)
12-12-2017, 07:33 PM
#15
Melting Slicks
Member Since: Feb 2015
Location: Huntsville AL & Hills of Southern TN
Posts: 2,290
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Bet you'd love the .64 with your 3.70s. I'm often in OD puttering around at 45 and 1500-1600 if it's relatively flat. The real beauty is ~2100 at 70 tho. There's always 4th.
12-12-2017, 08:17 PM
#16
Drifting
I like the L79 and 30-30 cam, but want the added power from a roller. Right now I'm leaning toward the Howards 110325-10. Specs are....
278/286 225/233@.50" .525"/.530" 110/106
Specs are between the L79 and 30-30. And with the intake closing at 65 ABDC, I can use flat top pistons with the 60cc heads. Should be good for the street, have a decent lope, and be good for 400-425hp. Any thoughts?
278/286 225/233@.50" .525"/.530" 110/106
Specs are between the L79 and 30-30. And with the intake closing at 65 ABDC, I can use flat top pistons with the 60cc heads. Should be good for the street, have a decent lope, and be good for 400-425hp. Any thoughts?
In general, the cam's overlap will determine the idle quality, with higher effective overlap leading to a rougher idle and lower off-idle torque. A common metric for calculating the effective overlap is degrees*sq-in, which is sort of an integral that takes into account both the lift and duration of the overlap period. Accurate calculations require a computer.
For comparison purposes, my Engine Analyzer v3.9 software calculates the effective overlap, in degrees*sq-in, for the following cams:
L79 cam: 4.2
LT1 cam: 6.2
30-30 cam: 9.6
Your Proposed Howards cam: 8.9
So, think about the idle characteristics and the off-idle torque of the three OEM cams when you contemplate the idle characteristic you want for your build.
The Comp Cams 280HR that I mentioned in the description of my 383 build has a calculated effective overlap of 5.9. And, a 383 will tolerate more overlap than a 350.
I do a lot of in-town driving with my 383, and I'm glad that I did not go any more aggressive on the cam. However, this is really a personal choice for each owner. There are guys that love the 30-30 cam, but I think it's a dog below 3000 rpm and would not be fun to drive at low speeds in traffic (where much of my driving is is done).
Simply changing the LSA of the Howards cam to 114 degrees would bring the effective overlap down to 5.2, sort of mid way between effective overlap of the L79 and LT1. An LSA of 112 on the Howards cam yields a calculated overlap of 6.3, similar to the LT1 cam.
Just food for thought. This is really a personal choice, but you should be aware of what you are signing up for if you use the catalog version of the Howards cam you referenced.
12-12-2017, 09:04 PM
#17
Le Mans Master
Member Since: Nov 2003
Location: Maryland
Posts: 5,657
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St. Jude Donor '05, '09, '15
Drothgeb
I don't know why I didn't look before but you are less than 45 minutes from me. I would be happy to meet up with you and let you sample my Howards cam. PM me your phone number if you would like to take a ride.
Tom
I don't know why I didn't look before but you are less than 45 minutes from me. I would be happy to meet up with you and let you sample my Howards cam. PM me your phone number if you would like to take a ride.
Tom
Last edited by Sky65; 12-12-2017 at 09:05 PM.
12-12-2017, 09:11 PM
#18
I have what is basically a '71 LT-1 in my Camaro. It has ported GM 492 heads with 2.02/1.6 valves and flat top pistons for about 10:1 compression. I installed the motor with a Comp 280AR10 street roller in the car in '89. It probably has 15,000 miles on it since then. With a 2.62 first Super T-10 and 4.10 rear it ran 12.7 at 110 mph. (this was exceptional IMO in the early '90's when very few street cars were in the mid 12's.) 3400# weight so should be about 350 rwhp.
This is an awesome combo IME. It idles about 900 rpm with a nice mechanical lifter tick and pulls hard to 6500 rpm in first. They recommend a little more valve spring now then they did. The 950 part # spring I used is 150# seat so not too hard on the lifters.
I finished it off with MSD 6T and a Victor Jr. A modded Barry Grant 750 with 4 corner idle for fuel.
Your combo sounds excellent except for the sub 9:1 compression. I have no problem with my iron heads and 10:1 squeeze on '92
pump gas.
Really jealous of you guys and your OD's. Have a McLeod Street 5 speed destined for my '64 coupe...
This is an awesome combo IME. It idles about 900 rpm with a nice mechanical lifter tick and pulls hard to 6500 rpm in first. They recommend a little more valve spring now then they did. The 950 part # spring I used is 150# seat so not too hard on the lifters.
I finished it off with MSD 6T and a Victor Jr. A modded Barry Grant 750 with 4 corner idle for fuel.
Your combo sounds excellent except for the sub 9:1 compression. I have no problem with my iron heads and 10:1 squeeze on '92
pump gas.
Really jealous of you guys and your OD's. Have a McLeod Street 5 speed destined for my '64 coupe...
Last edited by Mike C#2; 12-12-2017 at 09:12 PM. Reason: Added overdrive. If only it were that easy!
12-13-2017, 08:34 AM
#19
Racer
Thread Starter
Just a cautionary note that this cam will have a pretty rough idle in a 350, and the off-idle torque will be down compared to some other options. So, if you like the lift and duration of this cam, you might want to consider getting a custom grind with increased LSA.
In general, the cam's overlap will determine the idle quality, with higher effective overlap leading to a rougher idle and lower off-idle torque. A common metric for calculating the effective overlap is degrees*sq-in, which is sort of an integral that takes into account both the lift and duration of the overlap period. Accurate calculations require a computer.
For comparison purposes, my Engine Analyzer v3.9 software calculates the effective overlap, in degrees*sq-in, for the following cams:
L79 cam: 4.2
LT1 cam: 6.2
30-30 cam: 9.6
Your Proposed Howards cam: 8.9
So, think about the idle characteristics and the off-idle torque of the three OEM cams when you contemplate the idle characteristic you want for your build.
The Comp Cams 280HR that I mentioned in the description of my 383 build has a calculated effective overlap of 5.9. And, a 383 will tolerate more overlap than a 350.
I do a lot of in-town driving with my 383, and I'm glad that I did not go any more aggressive on the cam. However, this is really a personal choice for each owner. There are guys that love the 30-30 cam, but I think it's a dog below 3000 rpm and would not be fun to drive at low speeds in traffic (where much of my driving is is done).
Simply changing the LSA of the Howards cam to 114 degrees would bring the effective overlap down to 5.2, sort of mid way between effective overlap of the L79 and LT1. An LSA of 112 on the Howards cam yields a calculated overlap of 6.3, similar to the LT1 cam.
Just food for thought. This is really a personal choice, but you should be aware of what you are signing up for if you use the catalog version of the Howards cam you referenced.
In general, the cam's overlap will determine the idle quality, with higher effective overlap leading to a rougher idle and lower off-idle torque. A common metric for calculating the effective overlap is degrees*sq-in, which is sort of an integral that takes into account both the lift and duration of the overlap period. Accurate calculations require a computer.
For comparison purposes, my Engine Analyzer v3.9 software calculates the effective overlap, in degrees*sq-in, for the following cams:
L79 cam: 4.2
LT1 cam: 6.2
30-30 cam: 9.6
Your Proposed Howards cam: 8.9
So, think about the idle characteristics and the off-idle torque of the three OEM cams when you contemplate the idle characteristic you want for your build.
The Comp Cams 280HR that I mentioned in the description of my 383 build has a calculated effective overlap of 5.9. And, a 383 will tolerate more overlap than a 350.
I do a lot of in-town driving with my 383, and I'm glad that I did not go any more aggressive on the cam. However, this is really a personal choice for each owner. There are guys that love the 30-30 cam, but I think it's a dog below 3000 rpm and would not be fun to drive at low speeds in traffic (where much of my driving is is done).
Simply changing the LSA of the Howards cam to 114 degrees would bring the effective overlap down to 5.2, sort of mid way between effective overlap of the L79 and LT1. An LSA of 112 on the Howards cam yields a calculated overlap of 6.3, similar to the LT1 cam.
Just food for thought. This is really a personal choice, but you should be aware of what you are signing up for if you use the catalog version of the Howards cam you referenced.
The area I live in is mostly rural, but it is being developed at an alarming rate. Most of the driving will be secondary roads and small towns. Although it will occasionally be driven in larger cities.
In the past I have owned cars with both the Lt-1 and the 30-30 cams. I loved driving my old 56 with 30-30 and 4.56s back in high school. I’d say I’m looking for a similar experience with this build. If it weren’t for the longevity of the lifters, I’d probably go with the XR268R.
The specs and curves for the 280HR is very similar to the Howard’s 110885. The 110325 has just a little more exhaust duration, but that does bump the overlap up a few degrees. Based on that the 280HR or 110885 may be a better choice. Either would work well with my compression.
BTW what are you running for a CR?
I have what is basically a '71 LT-1 in my Camaro. It has ported GM 492 heads with 2.02/1.6 valves and flat top pistons for about 10:1 compression. I installed the motor with a Comp 280AR10 street roller in the car in '89. It probably has 15,000 miles on it since then. With a 2.62 first Super T-10 and 4.10 rear it ran 12.7 at 110 mph. (this was exceptional IMO in the early '90's when very few street cars were in the mid 12's.) 3400# weight so should be about 350 rwhp.
This is an awesome combo IME. It idles about 900 rpm with a nice mechanical lifter tick and pulls hard to 6500 rpm in first. They recommend a little more valve spring now then they did. The 950 part # spring I used is 150# seat so not too hard on the lifters.
I finished it off with MSD 6T and a Victor Jr. A modded Barry Grant 750 with 4 corner idle for fuel.
Your combo sounds excellent except for the sub 9:1 compression. I have no problem with my iron heads and 10:1 squeeze on '92
pump gas.
Really jealous of you guys and your OD's. Have a McLeod Street 5 speed destined for my '64 coupe...
This is an awesome combo IME. It idles about 900 rpm with a nice mechanical lifter tick and pulls hard to 6500 rpm in first. They recommend a little more valve spring now then they did. The 950 part # spring I used is 150# seat so not too hard on the lifters.
I finished it off with MSD 6T and a Victor Jr. A modded Barry Grant 750 with 4 corner idle for fuel.
Your combo sounds excellent except for the sub 9:1 compression. I have no problem with my iron heads and 10:1 squeeze on '92
pump gas.
Really jealous of you guys and your OD's. Have a McLeod Street 5 speed destined for my '64 coupe...
You misunderstood my CR. With mine dynamic compression would be 8.6:1 with IVC closing at 65 ABDC. Actual static CR will be a little over 10.8:1.
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Mike C#2 (12-13-2017)
12-13-2017, 10:00 AM
#20
Racer
Thread Starter
I disagree. The cams you are looking at have about 20 degrees less duration than mine has on both sides. I can easily shift into 5th at 45 MPH and pull away. I can easily cruise @ 2000 @60 although I usually cruise @ 2500 @ 80.
Ineresting to hear. Reviews that I could find on the 110325 indicated that it did pull well from idle, but cruised best in the mid 2000s
If I were you, I'd use a hydraulic roller of around 220 degrees duration on both sides with a wide LSA to cut down overlap because of your corked intake and exhaust. I'd install it advanced a couple degrees to give more DCR and I'd have no problem running .035 quench so long as you have non-stock connecting rods. With stock rods, I'd go no less than .040.
The car will likely have headers and 2.5” exhaust. I’ll likely be swapping out the 2x4s for a single on occasion too, especially if I take it too the track. My target duration is mid 220s @.050”, LSA 110. Exhaust maybe as high as 230.
You have to make up your mind whether you want to sacrifice torque for a "mean" sounding engine.
Looking for a balance between the two. Having good low end torque is great, but if it’s not combined with good top end hp, it’s just not as fun to drive. Car need’s to pull hard to 6000rpm. Needs to sound good too.
Hydraulic rollers are NOT subject to the same harshness of solid rollers so needle bearing scatter should not be a consideration. If you insist on a solid roller then using EDM oiling holes in the lifters and a rev kit will protect the lifters.
I have no concerns at all about hydraulic rollers, just the solids. If I do go solid roller, it will definitely have presssurized lifters and rev kit
The results I posted earlier are RWHP, in case you didn't notice. That's about 475 or so flywheel.
Ineresting to hear. Reviews that I could find on the 110325 indicated that it did pull well from idle, but cruised best in the mid 2000s
If I were you, I'd use a hydraulic roller of around 220 degrees duration on both sides with a wide LSA to cut down overlap because of your corked intake and exhaust. I'd install it advanced a couple degrees to give more DCR and I'd have no problem running .035 quench so long as you have non-stock connecting rods. With stock rods, I'd go no less than .040.
The car will likely have headers and 2.5” exhaust. I’ll likely be swapping out the 2x4s for a single on occasion too, especially if I take it too the track. My target duration is mid 220s @.050”, LSA 110. Exhaust maybe as high as 230.
You have to make up your mind whether you want to sacrifice torque for a "mean" sounding engine.
Looking for a balance between the two. Having good low end torque is great, but if it’s not combined with good top end hp, it’s just not as fun to drive. Car need’s to pull hard to 6000rpm. Needs to sound good too.
Hydraulic rollers are NOT subject to the same harshness of solid rollers so needle bearing scatter should not be a consideration. If you insist on a solid roller then using EDM oiling holes in the lifters and a rev kit will protect the lifters.
I have no concerns at all about hydraulic rollers, just the solids. If I do go solid roller, it will definitely have presssurized lifters and rev kit
The results I posted earlier are RWHP, in case you didn't notice. That's about 475 or so flywheel.
Too give you better insight on my driving style. I regularly drive a twin turbo diesel truck. It makes 964 RWHP (with no correction factor) and turns mid 10s with street tune and tires. Good spooling starts low 2000s and it has a 2800 stall converter. So I am use to keeping the rpms up to suit the build. Kinda enjoy the rpms.
If it weren’t for my wife driving the car some, I’d probably be looking at bigger cams. But with her driving it, it needs to have a balance between torque and hp.