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I have reviewed a lot of Isky cam profiles and have not seen any that resemble your cams specs. Most of their cams are single pattern and on a 108 Lsa. I had a 76 L82 with AT and 3.08 and my buddies 76 L48 with same gears and AT had much better low and mid range power. I later installed an Isky 264 mega cam with 214-214 .450-.450 lift on a 108 lsa. Had much better low and mid range and would leave my buddies 76 in the dust! Your Isky cam must have been a very special order grind. I would call them and ask them about it and get a recommendation on a cam from them. Another friend put the 290 Gm crate motor in his mid 70s Camaro and it was a real dog off the line with his 3.08 gears. He put in a set of Rhoads lifters and problem solved. I have used Rhoads in two different overcammed engines when I was too lazy to change the cams! They do work. I have read that the 290 motors are lucky to have 8.5 c.r. ! Not exactly what the L82 was designed for.
Checkout the Comp 268h. A step up would be the XE 262h. I have a 327 with a 9.25 cr and 492 heads with the XE 262. Smooth idle with a little lope and good vacuum. Good low end torque too.
[QUOTE=wesmigletz;1596948685]Here is a 62 870 Block with a 3.875" stroke Callies crank. IIRC, the rods are SJ oliver.
/QUOTE]
Wow, those are some serious notches! I'm surprised that you did not hit water.
I'm impressed that you got even more stroke than a 383 uses (3.875 vs 3.750). I guess it helped that the rods were small journal rods, but this is still an impressive stroke for an '870 block.
Did you keep the crankshaft main journals at the small journal size? If so, did you feel comfortable having such a big stroke with both the mains and the rod journals being the small journal size? I know some people think that might weaken the crank, but I've wondered whether using a really good crank material would compensate for the smaller journals.
Based on two 151 cams I stuck in 300 hp 327's with "advertised" compression of 10-1, they ran great and improved performance measurably.
They make the 300 hp cam look like the dog it is.
Here are comparisons of stock configured engines. Keep in mind that the OP's engine is using flat top pistons like a 327/300 and is therefore no longer a stock 327/350 if it had the 151 cam installed. Deduct 10% torque across the entire rev range for a 327/350 using flat tops in the following comparison:
Quote: Originally Posted by JohnZ Don't have the curves handy, but here are the peaks:
327/250hp @ 4400, 350 ft-lbs @ 2800
327/300hp @ 5000, 360 ft-lbs @ 3200
327/350hp @ 5800, 360 ft-lbs @ 3600
(***added by 65 tripleblack............327/350hp using flat top pistons 315hp @ 5800, 334 ft-lbs @ 3600)
327/365hp @ 6200, 350 ft-lbs @ 4000
The 327/300 has better/earlier torque than any of its siblings
Go back and reread the OP's first post where he states that most of his driving is done at 3000 or less RPM. He's not looking for HP, but he IS looking for torque. But, you don't understand what the difference is and I don't have the patience to explain it to you.
The 929 is not a "dog" as you say, and will give the OP more torque in his preferred rev range than either the 962 or 151 cam will. It will also give him the velvety smooth idle that he seems to want.
Again, if he had domed pistons installed, his choices would include either the 151 or, preferably the 962.
Last edited by 65tripleblack; 04-09-2018 at 10:55 AM.
I have read that the 290 motors are lucky to have 8.5 c.r. ! Not exactly what the L82 was designed for.
The L-82 advertised CR is 9:1, but is probably lower due to most deck heights being high as the broach tools wore. The same likely applies to current GM crate engines, but the 350/290 is barely lower.
Base cam engines make more torque/power up to somewhere in the 3000-4000 range, so with the same gearing, the base engine will be quicker off the line, but that's why SHP cam engines usually have shorter axle ratios than base cam engines.
The L-82 advertised CR is 9:1, but is probably lower due to most deck heights being high as the broach tools wore. The same likely applies to current GM crate engines, but the 350/290 is barely lower.
Base cam engines make more torque/power up to somewhere in the 3000-4000 range, so with the same gearing, the base engine will be quicker off the line, but that's why SHP cam engines usually have shorter axle ratios than base cam engines.
Duke
The 350/290 crate engine is a slug in many cars, especially heavier ones with this cam. The smog heads are 76cc and elss than 9:1 compression. I put this engine in my '68 Impala Wagon and it was terrible with that combination. I switched heads to a 64cc Dart heads I had on the shelf. I also swapped the cam for a Lunati 101 grind. This solved all the problems and car runs great. When I broke the cam in my '62 with 70 LT-1 short block late last summer I used the cam from the 350/290. That combination with the 64 cc heads is great with the lighter weight Corvette. Many others on other forums also wonder why GM used this cam in the 350/290 engine
I recall years ago the 350/290 or whatever the lowest rated crate motor was used the 300 HP cam - 3896929 or its superseding part number that has the same basic specs - just lobe dynamics refinements. That config. would have been better for a heavy car with tall gears, but most street rods, whether a '32 Coupe or a '55 Chevy are lighter, and usually shorter geared.
I expect the street rod set was disappointed with this engine because it didn't have any "idle attitude", so GM swapped in the longer duration, higher overlap 962 cam, which cost low end torque and power, but I expect sales went up.
I recall 10 to 15 years ago there was a Chevy dealer - up around Seattle IIRC - that sold a lot of these engines, but swapped out the 929 for a 962 and offered the removed 929 for ten bucks plus shipping. Smokin' deal! Maybe that's why GM swapped out the 929 for the 962 from the engine plant. Most customers probably liked the 962 better.
I think one reason for poor performance is that buyers have to install their own distributor and I doubt if one out of 100 know how to properly configure the spark advance map for this engine configuration, which is probably a big part of the "problem".
I think one reason for poor performance is that buyers have to install their own distributor and I doubt if one out of 100 know how to properly configure the spark advance map for this engine configuration, which is probably a big part of the "problem".
Duke
It’s usually a good idea to have a new build Dyno-tuned.
That assumes that the guy actually knows what a good spark advance map is for any given engine.
My tuning seminar offers some good starting points for all Gen I SBCs and Mark IV big blocks, OE or modified. All you need to know is manifold vacuum @ idle speed, SCR, and fuel octane rating. It's not rocket science.
On my engine system engineering projects we (me and the owner) usually dial in the spark advance map with road test using SOTP impressions. Then it's off to the chassis dyno to get the performance curves with maybe a little fine tuning... usually just the initial timing because we've already determined via road testing the most aggressive detonation-free centrifugal curve that the engine will tolerate.
I don't want to get off topic of my cam selection objective, but I am curious to know your thoughts on the attached timing curves. I checked it and confirmed my current set up is the "Red" curve .. 16 base, 10 Vac, 18 mechanical all in at 2500 rpm.
I have been doing a bunch of reading and research and while I don't have the practical experience most of the forum members do , I am getting a better understanding of the effects of the various valve timing events and cam shaft design.
LSA: range 108-114 degrees, lower LSA makes more torque, but has poor idle quality... for me and my set up I think 110-112 will give me the idle and torque I am wanting
Overlap: good torque and street performance range 45-60 degrees
Duration: Advertised range 250 -300 / @.50 range 212 - 235, for me and my set up 260-280 / @.50 212 - 224 is probably a good range
DCR: higher is better, my current SC is around 9:1 maybe a little better, I use non-ethanol 90 fuel and my cranking compression is only 160 psi and should be 180 psi or higher, ISKY has an early IVC, so not sure why cranking compression is down since cylinder walls looked great on the scope.
Single vs Dual Pattern: dual pattern cams with longer exhaust duration is better suited for high RPM HP, which is not what i am after, so single pattern
Lift: range .390 to .485. more is generally better and will make more torque and thus more HP.
Given what I have learned taking to techs at Crane, and Comp, articles, and the dyno data from various sources and real world posts from forum members I am leaning toward the Comp Cam 268H
One thing I would like to mention though, is that the timing specs for most of the GM cams are from the beginning of lobe lift, whereas the Comps are measured at .006” lobe lift. According to Comp and some other manufacturers, it takes .006” of lobe lift to compress a hydraulic lifter enough to actually get the valve off the seat. So the longer durations stated by GM isn’t quite an apples to apples comparison.
Yes it is a challenge to compare cams when valve events are not reported at the same lift point. I pulled GM data from multiple sources and they did not all agree or use the same lift point. It would interesting if somone actually maped the GM cams using .006 and 0.50 lift.
How did you like the xe262? That is the other cam i think i will like. What exhaust do you have? What is your vacumm at 800 rpm? Do you have audio?
I only very briefly ran it last fall as a test cam, before tearing the car down over the winter for a refurb. As compared to the original 929 cam, it had better low end torque and quite a bit more upper rpm hp. I should also point out that the original engine had low 9s compression, so the 929 cam wasn’t a great match to begin with. With the Xe262 it sounded and ran good, at 800 vacuum was 16-17. All around it was a great street cam. Car has 2 1/2” manifolds and exhaust, M20 with 3.70s. As compared to the 268h, the XE262 has the better top end, 268h has a better bottom end.
Since tearing the car down, I’ve decided to build a different engine. New engine will have a hydraulic roller and aluminum heads, but somewhat similar specs. New cam will be 225/225@.050”, DCR will be 8.5 +/-.
BTW, if you are considering one of the Comps, also check out the Lunati Voodoos. Supposedly the Voodoo 262 is better than either Comp.
I don't want to get off topic of my cam selection objective, but I am curious to know your thoughts on the attached timing curves. I checked it and confirmed my current set up is the "Red" curve .. 16 base, 10 Vac, 18 mechanical all in at 2500 rpm.
I have been doing a bunch of reading and research and while I don't have the practical experience most of the forum members do , I am getting a better understanding of the effects of the various valve timing events and cam shaft design.
LSA: range 108-114 degrees, lower LSA makes more torque, but has poor idle quality... for me and my set up I think 110-112 will give me the idle and torque I am wanting
Overlap: good torque and street performance range 45-60 degrees
Duration: Advertised range 250 -300 / @.50 range 212 - 235, for me and my set up 260-280 / @.50 212 - 224 is probably a good range
DCR: higher is better, my current SC is around 9:1 maybe a little better, I use non-ethanol 90 fuel and my cranking compression is only 160 psi and should be 180 psi or higher, ISKY has an early IVC, so not sure why cranking compression is down since cylinder walls looked great on the scope.
Single vs Dual Pattern: dual pattern cams with longer exhaust duration is better suited for high RPM HP, which is not what i am after, so single pattern
Lift: range .390 to .485. more is generally better and will make more torque and thus more HP.
Given what I have learned taking to techs at Crane, and Comp, articles, and the dyno data from various sources and real world posts from forum members I am leaning toward the Comp Cam 268H
I don't want to get off topic of my cam selection objective, but I am curious to know your thoughts on the attached timing curves. I checked it and confirmed my current set up is the "Red" curve .. 16 base, 10 Vac, 18 mechanical all in at 2500 rpm.
I have been doing a bunch of reading and research and while I don't have the practical experience most of the forum members do , I am getting a better understanding of the effects of the various valve timing events and cam shaft design.
LSA: range 108-114 degrees, lower LSA makes more torque, but has poor idle quality... for me and my set up I think 110-112 will give me the idle and torque I am wanting
Overlap: good torque and street performance range 45-60 degrees
Duration: Advertised range 250 -300 / @.50 range 212 - 235, for me and my set up 260-280 / @.50 212 - 224 is probably a good range
DCR: higher is better, my current SC is around 9:1 maybe a little better, I use non-ethanol 90 fuel and my cranking compression is only 160 psi and should be 180 psi or higher, ISKY has an early IVC, so not sure why cranking compression is down since cylinder walls looked great on the scope.
Single vs Dual Pattern: dual pattern cams with longer exhaust duration is better suited for high RPM HP, which is not what i am after, so single pattern
Lift: range .390 to .485. more is generally better and will make more torque and thus more HP.
Given what I have learned taking to techs at Crane, and Comp, articles, and the dyno data from various sources and real world posts from forum members I am leaning toward the Comp Cam 268H
If you go to Speed Pro's specs on their blueprint GM camshafts, you'll find durations @ .006 valve lift (SAE J604d specification).
Here is one example:
CS179R (blueprint 151 [L79] cam) : 290/290
SWC Duke has the FM part number part number for the 929 cam replacement as CS274. Based on what you see with the 151 cam, I'd say that the .006 duration of the 929 is around 245-255 degrees. This will maintain your current SCR, which is very acceptable as well as providing smooth idle and much more torque than you have with your current camshaft. FM "cam cards" showing complete specs are not easy to find online. Every time I call their Tech Help group, they have been good enough to FAX me copies of their "cam cards". You should do this on Monday to verify the durations @ .006. If you post the cam card image once you get it, it will probably be much appreciated by more than a few guys around here.
The aftermarket cams have faster lobe ramps than OEM cams, and that's why their .006 durations are shorter, although having similar .050 durations. This is fantastic for torque production, but be aware that durability will suffer. Most aftermarket cams will require a larger diameter spring, which will require machine work to enlarge the spring pockets as well as installing screw in rocker studs.
If you want to change to an aftermarket camshaft, then I'd suggest that you use a hydraulic roller.
Last edited by 65tripleblack; 04-15-2018 at 09:06 AM.
Intake Open 15 BTC, Open @.50 4 ATC / Max lift: .277 (.416) @ 110 ATC
Intake Close @.50 29 ABC, Intake Close 48 ABC
Intake Duration 243 degrees/ 205 degrees @.50
Exhaust: Open 72 BBC, Open @.50 42 BBC / Max lift: .310 (.465) @ 106 BTC
Exhaust: Close 50 ATC, Close @.50 4 ATC
Exhaust Duration: 302 degrees/ 226 degrees@.50
LSA = 108 degrees
I interpret these events to indicate:
1) ISKY Cam is retarded 4 degrees since LSA – ICL = -4
2) Overlap seat to seat = 65 degrees (50+15)
THANKS in advance for taking the time!
No Isky catalog cam comes close to your measurements.
The Isky lobe profile specs that come closest to your profile measurements are:
Intake options:
Lobe lift 0.415
=> 224, 232, or 240 duration at 0.050"
=> 272, 264, or 280 duration (advertised)
Exhaust options:
Lobe lift 0.465
=> 221 or 224 duration at 0.050"
=> 270 or 280 duration (advertised)
If the cam is a mix of these I & E profiles it is a typical 2000-5800 rpm SBC cam for a car with headers and 3.73-4.10 gears. The 108 LCA is the problem if you want a smooth idle, as the ICL can be moved with an adjustable timing set to gain or reduce the DCR. It is odd cam timing for Isky.
The closest catalog cam is the 270-MEGA @ 0.465 lift and 270 advertised duration (221 @ 0.050), I & E, on a 108 LCA. It's a bit rough for idle quality, but makes good torque, and they say it revs to 6200. It is a variation of the GM 350hp cam ground on a tight LCA for an engine with open headers (they typical Sunday bracket car combination).
ED at Isky (the old man) was not an advocate of split pattern cams, because he preached porting to get a 80% E/I air flow ratio, to make best power. He was also impatient with specifying cams for exhaust manifolds and restrictive exhaust, as he promoted racing. To address this thinking the catalog cams are almost all equal lobe patterns in I & E, and most have a LCA of 108 or less to gain the VE benefits of a free flowing exhaust mass. They were almost all lumpy idle cams (that "Isky" sound).
Isky would, and they still will, grind any combination of their lobe profiles in a split pattern and LCA (just call Ron, the extra cost is minimal and the lobe profiles are near the back of the catalog).
It sounds like a GM 929 cam (300HP) will address your needs, although SWCDuke probably has some attractive alternatives to consider.
Isky still has the old 270L HL #201270 cam with 216-216 @ .050 .445-.445 lift on a 108 lsa which would be milder than the 270 Mega and have a better idle and with slightly better low and mid range.
[QUOTE=63 340HP;1597000290]No Isky catalog cam comes close to your measurements.
The Isky lobe profile specs that come closest to your profile measurements are:
Intake options:
Lobe lift 0.415
=> 224, 232, or 240 duration at 0.050"
=> 272, 264, or 280 duration (advertised)
Exhaust options:
Lobe lift 0.465
=> 221 or 224 duration at 0.050"
=> 270 or 280 duration (advertised)
If the cam is a mix of these I & E profiles it is a typical 2000-5800 rpm SBC cam for a car with headers and 3.73-4.10 gears. The 108 LCA is the problem if you want a smooth idle, as the ICL can be moved with an adjustable timing set to gain or reduce the DCR. It is odd cam timing for Isky.
Thanks! I could not find anything in the ISKY catalog either and assumed it was custom ground. The engine was built in 2001, and I sent an email to ISKY asking them about this cam but have not heard back. I just took that car out and got some fuel in it. It has plenty of torque from 2000 to 5000. The concern I have is, the car and engine shakes so violently and erratically as the car is warming up it does not look happy, Once you hit the throttle its happy, and sounds healthy as the side pipes roar...
This was hashed out a month or two ago. Use the L-46/82 cam. It's very close to the L-79, but with better lobe dynamics and the IPOML is indexed four degrees later, so it should be installed with the OE replacement truck roller chain set (made by Cloyes and available at NAPA for about 25 bucks) that has +/- 4 degrees adjustment and you want to advance it 4 degrees on a 327 to bring the IPOML back to 110 (same as the L-79).
This cam is used today in the GM 350/290 HP crate engine with 8.5:1 CR. Typical idle behavior is 14-15" @ 750. It has an excellent blend or low end torque and top end power, especially if the spark advnance map is optimized, and it can be very aggressive.
There is a nearby active thread on this subject, too.
Duke
SWCDuke ,
How do I advance he cam 4 degrees ?
I know I need a timing set with 3 keyways , but do I use the keyway at
4 o'clock or the one at 8 o'clock ?
04-08-2018, 11:34 AM
The 350/290 crate engine is a slug in many cars, especially heavier ones with this cam. The smog heads are 76cc and elss than 9:1 compression. I put this engine in my '68 Impala Wagon and it was terrible with that combination. I switched heads to a 64cc Dart heads I had on the shelf. I also swapped the cam for a Lunati 101 grind. This solved all the problems and car runs great. When I broke the cam in my '62 with 70 LT-1 short block late last summer I used the cam from the 350/290. That combination with the 64 cc heads is great with the lighter weight Corvette. Many others on other forums also wonder why GM used this cam in the 350/290 engine
