Need a camshaft choice 66 327
03-02-2018, 08:29 PM
#42
Racer
SCR is the static CR, which is the calculated CR minus the adjustment of when the intake valve closes. This is what most call the compression ratio.
It sounds like the OP has dome pistons, which is a good match for the L79 cam, and gives a DCR of around 8:1.
Personally, I don’t like dome pistons. If I were the OP, I would run flat top pistons and one of the cams I mentioned. Good compromise between low end torque and top end power and still have a little lope.
03-03-2018, 12:19 AM
#44
Advanced
Thread Starter
There's as much misunderstanding over what is a so-called old school/new school cam as there is about what an "assault rifle" is.
Consider that the valve train on the Gen I small block is no where near as stiff as a modern LS engines with roller lifters. It's definitely "old school", and if you push it too far beyond OE you can have reliability problems like wiped out lifter and lobes. Of course, you can spend hundreds of dollars to stiffen it up a bit - may to "semi-new school" standards, but what's the point on a car you just want to enjoy driving around in. this is clearly one of my concerns, i am sending the heads out any way. and may do screw in studs..but it will add to the list of things i wasnt high on my list..but its prolly good insurance.
The other thing that defines "old school" are the cam's POMLs and LSA. Of the hundreds of aftermarket hot rod cam designs on the markte, today, the POMLs, like 106 and 114/110 LSA, are decidedly old school compared to modern LS OE cams because most of them were designed 30-50 years ago for headers and open exhaust. yes there are literally pages.. i dont want detination if it has pop up pistons.. this is why i am hanging with the vette crowd who have dealt with this. this paragraph highlights why I am here. lots of stock parts to maximize.
Both the base and L-79 cams are also old school in terms of these parameters, but durations are shorter and LSAs wider, which is why they offer a better driving experience and better durability than most aftermarket hot rod cams. i am following what your saying.
The McCagh Special is old school lobe dynamics since it uses the same lobes as the 300 HP cam, but they are swapped and the inlet event is phased very late. This is "new school", and why the inlet event is near identical to the LS2/3 cams. I pointed this out in the "Tale of Two Camshafts" article.I havent read that article yet.. but i will. and i was leaning towards this thought process.
If you're really serious about parades install a 300 HP cam. If you can skip the parades, the L-79 cam has a very nice combination of low end torque and top end power, which is tough to beat and enough "attitude" at idle to know that it's a "real" Corvette engine, not one shared with a passenger car. Now its clear your following what im thinking. (he attends 1 parade a year. and its a pain but i am certain it will be there when its back to running). this car has been out of commission for 10 yrs.
An even better choice is the L-46/82 cam, installed four degrees advanced. That make the timing near identical to the L-79 cam, but it has better lobe dynamics and is easier on the valve train. ok i get this..
Something else to consider, especially if the 283 is original to the car, is rebuild it, and you can always drop in a 327 Crank (with some block clearance checks) to make it a 307 with the standard bore, and the longer stroke means more torque.maybe some day but its not that important at this time (we will be moth ball the 283 for future numbers matching consideration)
I'm your father's age and road raced cars for 30 years. Been there, done that. I still like to attack a corner once in a while, but nowadays I prefer a decent ride and a very tractable/torquey engine with a smooth idle. I'm done dealing with cantankerous beasts. Sometimes you have to break with the past and move on, but I still refuse to own anything with an automatic transmission. pretty much dead on. but why leave hp if i dont have to .. which i am following what youve been saying. and its still in flux as far as decisions. I am appreciating your perspectives .and line of thinking.
Duke
Consider that the valve train on the Gen I small block is no where near as stiff as a modern LS engines with roller lifters. It's definitely "old school", and if you push it too far beyond OE you can have reliability problems like wiped out lifter and lobes. Of course, you can spend hundreds of dollars to stiffen it up a bit - may to "semi-new school" standards, but what's the point on a car you just want to enjoy driving around in. this is clearly one of my concerns, i am sending the heads out any way. and may do screw in studs..but it will add to the list of things i wasnt high on my list..but its prolly good insurance.
The other thing that defines "old school" are the cam's POMLs and LSA. Of the hundreds of aftermarket hot rod cam designs on the markte, today, the POMLs, like 106 and 114/110 LSA, are decidedly old school compared to modern LS OE cams because most of them were designed 30-50 years ago for headers and open exhaust. yes there are literally pages.. i dont want detination if it has pop up pistons.. this is why i am hanging with the vette crowd who have dealt with this. this paragraph highlights why I am here. lots of stock parts to maximize.
Both the base and L-79 cams are also old school in terms of these parameters, but durations are shorter and LSAs wider, which is why they offer a better driving experience and better durability than most aftermarket hot rod cams. i am following what your saying.
The McCagh Special is old school lobe dynamics since it uses the same lobes as the 300 HP cam, but they are swapped and the inlet event is phased very late. This is "new school", and why the inlet event is near identical to the LS2/3 cams. I pointed this out in the "Tale of Two Camshafts" article.I havent read that article yet.. but i will. and i was leaning towards this thought process.
If you're really serious about parades install a 300 HP cam. If you can skip the parades, the L-79 cam has a very nice combination of low end torque and top end power, which is tough to beat and enough "attitude" at idle to know that it's a "real" Corvette engine, not one shared with a passenger car. Now its clear your following what im thinking. (he attends 1 parade a year. and its a pain but i am certain it will be there when its back to running). this car has been out of commission for 10 yrs.
An even better choice is the L-46/82 cam, installed four degrees advanced. That make the timing near identical to the L-79 cam, but it has better lobe dynamics and is easier on the valve train. ok i get this..
Something else to consider, especially if the 283 is original to the car, is rebuild it, and you can always drop in a 327 Crank (with some block clearance checks) to make it a 307 with the standard bore, and the longer stroke means more torque.maybe some day but its not that important at this time (we will be moth ball the 283 for future numbers matching consideration)
I'm your father's age and road raced cars for 30 years. Been there, done that. I still like to attack a corner once in a while, but nowadays I prefer a decent ride and a very tractable/torquey engine with a smooth idle. I'm done dealing with cantankerous beasts. Sometimes you have to break with the past and move on, but I still refuse to own anything with an automatic transmission. pretty much dead on. but why leave hp if i dont have to .. which i am following what youve been saying. and its still in flux as far as decisions. I am appreciating your perspectives .and line of thinking.
Duke
Its another thing to have put a choice cam in a vette run it and then compared it to a previous cam to determine if it was better or worse. I am just hoping to use your info and some of the good info others have posted to get me in the right direction.
I have run alot of cams in my smallblock mopar race car ...with multiple engine combos...Once in a while you find a cam that just kicks butt... i pivot based on that , when i am talking to any mopar smallblock racer and they ask my advice i have a foundation to pivot from. fwiw. if i was building a race car head flow would dictate alot.. but since this is basically a stock vette i figure others have already done one . no need to guinea pig.
03-03-2018, 12:47 AM
#45
Advanced
Thread Starter
IF the transmission is indeed a 63, then it is a one year only because of the bearing retainer diameter and requires a one year only bellhousing.
my .02... for driving around town you need a 1st gear with the highest # you can find, the rule of thumb for ideal transmission/rearend ratio is 1st times rer should be 10 or above. for example, my MY6 has a 3.07 1st and with a 3.36 rer, equals 10.32 and was a pleasure to drive. my SS700 with a 2.66 and the 3.36 equals 8.94, not as much fun...
Bill
my .02... for driving around town you need a 1st gear with the highest # you can find, the rule of thumb for ideal transmission/rearend ratio is 1st times rer should be 10 or above. for example, my MY6 has a 3.07 1st and with a 3.36 rer, equals 10.32 and was a pleasure to drive. my SS700 with a 2.66 and the 3.36 equals 8.94, not as much fun...
Bill
03-03-2018, 01:39 AM
#46
Le Mans Master
On my dad's 66' L79, we rebuilt it with a Crane Z-274. Its a very mild lobe and the valve train is real quiet. Its 224/230*, and around .470/.480" lift on a 110 lsa. This car is a factory type resto with factory manifolds/side pipes etc. We did lower the compression with flat tops though, its around 9.5-1. The car drives great, plenty of torque and no cam surge, idles smoothly at 600-700 rpms. However, it does have 3.70 gears. It definitely has a little lope to it, sounds very similar to our 67' L79 car that is 100% original.
If that is a little too much, I would look into the XE262.... I certainly wouldn't go any smaller then that.
I would look into the Crane Z-274 though, its just a more modern version of the L79 cam, but with milder lobes then a XE268 comp.
If that is a little too much, I would look into the XE262.... I certainly wouldn't go any smaller then that.
I would look into the Crane Z-274 though, its just a more modern version of the L79 cam, but with milder lobes then a XE268 comp.
Last edited by ajrothm; 03-03-2018 at 01:43 AM.
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cheapstreetduster (03-03-2018)
03-03-2018, 08:02 AM
#47
Drifting
FWIW, I was looking to purchase the GM 300 cam and found, as someone pointed out, a huge price diff between the cs-274 and supposed clone, under part # cs1103r. the specs are close but there are some differences. No clue how significant those differences are. ??
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cheapstreetduster (03-03-2018)
03-03-2018, 10:37 AM
#48
Pro
Great thread. I learned alot, which is good for me because thinking about what to do with my 327 that is dressed up like a 365hp, "567" block casting, angle plug heads, Edelbrock TM-1 intake, Holley 600cfm double pumper (4150), and long tube headers with side pipes. No clue on the cam, but can sure hear the solid lifters. Might buy a For Sale locally "870" short block and build me the "right" engine?
PO of my 65 convertible can take all the credit for this hybrid heap....
PO of my 65 convertible can take all the credit for this hybrid heap....
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cheapstreetduster (03-04-2018)
03-03-2018, 09:41 PM
#49
Advanced
Thread Starter
On my dad's 66' L79, we rebuilt it with a Crane Z-274. Its a very mild lobe and the valve train is real quiet. Its 224/230*, and around .470/.480" lift on a 110 lsa. This car is a factory type resto with factory manifolds/side pipes etc. We did lower the compression with flat tops though, its around 9.5-1. The car drives great, plenty of torque and no cam surge, idles smoothly at 600-700 rpms. However, it does have 3.70 gears. It definitely has a little lope to it, sounds very similar to our 67' L79 car that is 100% original.
If that is a little too much, I would look into the XE262.... I certainly wouldn't go any smaller then that.
I would look into the Crane Z-274 though, its just a more modern version of the L79 cam, but with milder lobes then a XE268 comp.
If that is a little too much, I would look into the XE262.... I certainly wouldn't go any smaller then that.
I would look into the Crane Z-274 though, its just a more modern version of the L79 cam, but with milder lobes then a XE268 comp.
thanks.. and pretty cars ... I am partial to green.
03-04-2018, 07:25 AM
#50
Racer
To give you good input on a cam, you need to know what your actual static compression ratio is.
If you have flat tops and somewhere around 9.5:1, there are plenty of cam choices to meet your goal. The ones I mentioned earlier are all good choices, and there are more out there.
If you have ~10.5:1 or more, then your choices are limited. Because you’ll end with more duration than you want just to lower your DCR to an acceptable level. If you do end up with a longish duration cam, consider a single pattern cam to preserve as much torque as possible.
If you have flat tops and somewhere around 9.5:1, there are plenty of cam choices to meet your goal. The ones I mentioned earlier are all good choices, and there are more out there.
If you have ~10.5:1 or more, then your choices are limited. Because you’ll end with more duration than you want just to lower your DCR to an acceptable level. If you do end up with a longish duration cam, consider a single pattern cam to preserve as much torque as possible.
03-04-2018, 11:53 AM
#51
Advanced
Thread Starter
To give you good input on a cam, you need to know what your actual static compression ratio is.
yes.. its still got the starter on it so i may crank it over on the stand and see what kind of compression psi it has as it its right now.
just for the record again i am not looking to build a cam... i am looking for guys who's c2 experience with a cam gave them good results.
If you have flat tops and somewhere around 9.5:1, there are plenty of cam choices to meet your goal. The ones I mentioned earlier are all good choices, and there are more out there. Yes and thanks . there is alot of choices on paper...
If you have ~10.5:1 or more, then your choices are limited. Because you’ll end with more duration than you want just to lower your DCR to an acceptable level. If you do end up with a longish duration cam, consider a single pattern cam to preserve as much torque as possible i an not apposed to this... .
yes.. its still got the starter on it so i may crank it over on the stand and see what kind of compression psi it has as it its right now.
just for the record again i am not looking to build a cam... i am looking for guys who's c2 experience with a cam gave them good results.
If you have flat tops and somewhere around 9.5:1, there are plenty of cam choices to meet your goal. The ones I mentioned earlier are all good choices, and there are more out there. Yes and thanks . there is alot of choices on paper...
If you have ~10.5:1 or more, then your choices are limited. Because you’ll end with more duration than you want just to lower your DCR to an acceptable level. If you do end up with a longish duration cam, consider a single pattern cam to preserve as much torque as possible i an not apposed to this... .
Then i may as well put the fly wheel back on and do a compression check.. this should be helpful especially once i pull the cam thats in there ,,and hopefully id it... Ill have a reference. and some concept of the compression ratio... at least preliminarily.
Last edited by cheapstreetduster; 03-04-2018 at 11:57 AM.
03-04-2018, 01:01 PM
#52
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Search for a thread started by me and download the compression ratio article. If you ascertain that it has the OE domed pistons the net dome volume is 5.3 cc. If they are flat determine whether they have two or four valve notches. Figure about 5 cc if four notches and 2.5cc with only two. That makes the piston a net "dish".
Also measure head gasket thickness. Assume nominal deck clearance of .025" and you have enough data to run through the CR calculator and get a ballpark CR.
Also measure head gasket thickness. Assume nominal deck clearance of .025" and you have enough data to run through the CR calculator and get a ballpark CR.
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cheapstreetduster (03-04-2018)
03-04-2018, 02:13 PM
#53
Race Director
When the original LT-1 camshaft broke in my '62 last year I replaced it with the L-46/82 I took out of the 350, 290 hp crate motor when that combo was a bad match for my '68 wagon. That cam works great in the 350 LT-1 short block in the Vette
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cheapstreetduster (03-04-2018)
03-04-2018, 03:55 PM
#54
Advanced
Thread Starter
i am in my garage and infront of the 327 engine.
just pulled the plugs and scoped inside a cyl.
this 327 has flat top pistons with 4 valve reliefs... and it looks like .o20 overbore... cant read that clearly.?.. definately doesnt look like a 3 it looks like a 2..?
so for what that is worth.. i will definately have to cc" every thing to get a straight static compression ratio.
i also cant put the flywheel on and crank it to get a cyl psi. the flywheel wont fit on the engine with this engine stand. so i may have to take it off the stand to put on the flywheel..and jump the starter to get a psi.
but CC" it will tell me what i need to know after i pull the heads..
wont be pulling the heads yet as i have too many other things going on in my garage right now.. so space is limited...
but i will be pulling the heads as soon as i can on this thing.
just pulled the plugs and scoped inside a cyl.
this 327 has flat top pistons with 4 valve reliefs... and it looks like .o20 overbore... cant read that clearly.?.. definately doesnt look like a 3 it looks like a 2..?
so for what that is worth.. i will definately have to cc" every thing to get a straight static compression ratio.
i also cant put the flywheel on and crank it to get a cyl psi. the flywheel wont fit on the engine with this engine stand. so i may have to take it off the stand to put on the flywheel..and jump the starter to get a psi.
but CC" it will tell me what i need to know after i pull the heads..
wont be pulling the heads yet as i have too many other things going on in my garage right now.. so space is limited...
but i will be pulling the heads as soon as i can on this thing.
03-04-2018, 04:10 PM
#55
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Close for review-
Re-open after review
—————-
Guys, I’d rather not close this thread yet as it contains some useful information.
However, some of that useful information was lost as it was intermingled with the pissing match that this page has turned into. I don’t intend to spend the time to edit out the bad stuff if people want to bicker.
Multiple moderators have deleted posts by at least 4 members in this thread. Please do not engage in conflict any further at any level, no matter how many emojis you add to it.
If you are frustrated with the OPs decided use of suggestions, please move on to a different thread rather than get into a personal exchange over it. If you are tempted to engage in a conflict that’s headed your way, please think better of it and report the post rather than responding.
Let’s stay on topic. If you aren’t enjoying the thread any more, don’t read it.
Re-open after review
—————-
Guys, I’d rather not close this thread yet as it contains some useful information.
However, some of that useful information was lost as it was intermingled with the pissing match that this page has turned into. I don’t intend to spend the time to edit out the bad stuff if people want to bicker.
Multiple moderators have deleted posts by at least 4 members in this thread. Please do not engage in conflict any further at any level, no matter how many emojis you add to it.
If you are frustrated with the OPs decided use of suggestions, please move on to a different thread rather than get into a personal exchange over it. If you are tempted to engage in a conflict that’s headed your way, please think better of it and report the post rather than responding.
Let’s stay on topic. If you aren’t enjoying the thread any more, don’t read it.
Last edited by vettebuyer6369; 03-04-2018 at 04:37 PM.
03-04-2018, 07:26 PM
#56
Advanced
Thread Starter
donor 66 327
its definately a .030 over 4 valve relief piston.. i went ahead and pulled the heads..
its 41 thou in the hole.. flat tops.
its definately a .030 over 4 valve relief piston.. i went ahead and pulled the heads..
its 41 thou in the hole.. flat tops.
03-05-2018, 11:26 AM
#57
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Sounds like maybe a GM replacement piston, but you need to pull the pan and look at the bottoms of the pistons to see what the data is.
Are you saying that piston- deck clearance is .041"? That's very high. You need to measure all eight and review for taper and side to side variation. This is the start of the CR management process that I discussed in the paper.
Does the block have the original numbers and broach marks, or does it appear to have been decked in the field?
How thick are the removed head gaskets....same on both sides?
Duke
Are you saying that piston- deck clearance is .041"? That's very high. You need to measure all eight and review for taper and side to side variation. This is the start of the CR management process that I discussed in the paper.
Does the block have the original numbers and broach marks, or does it appear to have been decked in the field?
How thick are the removed head gaskets....same on both sides?
Duke
Last edited by SWCDuke; 03-05-2018 at 11:41 AM.
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cheapstreetduster (03-05-2018)
03-05-2018, 05:31 PM
#58
Drifting
Sounds like maybe a GM replacement piston, but you need to pull the pan and look at the bottoms of the pistons to see what the data is.
Are you saying that piston- deck clearance is .041"? That's very high. You need to measure all eight and review for taper and side to side variation. This is the start of the CR management process that I discussed in the paper.
Does the block have the original numbers and broach marks, or does it appear to have been decked in the field?
How thick are the removed head gaskets....same on both sides?
Duke
Are you saying that piston- deck clearance is .041"? That's very high. You need to measure all eight and review for taper and side to side variation. This is the start of the CR management process that I discussed in the paper.
Does the block have the original numbers and broach marks, or does it appear to have been decked in the field?
How thick are the removed head gaskets....same on both sides?
Duke
Recently I read somewhere (possibly on this forum) that some "rebuilder pistons" used back in the day had reduced piston height to help ensure that there would be no complaints of detonation from customers.
My guess is that this the type of piston in my 327. Since the short block was in perfect operating condition, I just had the heads milled to get a slight compression bump from smaller 60 cc chambers and left things otherwise unchanged.
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cheapstreetduster (03-05-2018)
03-05-2018, 07:59 PM
#59
Drifting
A previous owner had my original 327 rebuilt in 1988. The pistons are .030" over flat tops with four reliefs. While I had the heads off I checked to see where the piston height was in relation to the deck, and I measured about .050". I was so surprised by this unusually high number that I checked it several times, but it always came out to about .050".
Recently I read somewhere (possibly on this forum) that some "rebuilder pistons" used back in the day had reduced piston height to help ensure that there would be no complaints of detonation from customers.
My guess is that this the type of piston in my 327. Since the short block was in perfect operating condition, I just had the heads milled to get a slight compression bump from smaller 60 cc chambers and left things otherwise unchanged.
Recently I read somewhere (possibly on this forum) that some "rebuilder pistons" used back in the day had reduced piston height to help ensure that there would be no complaints of detonation from customers.
My guess is that this the type of piston in my 327. Since the short block was in perfect operating condition, I just had the heads milled to get a slight compression bump from smaller 60 cc chambers and left things otherwise unchanged.
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cheapstreetduster (03-05-2018)
03-05-2018, 09:03 PM
#60
Drifting
need a hydraulic flat tappit cam for a 66 327 with slightly ported factory iron heads . the stock 2x4 intake, with 2.5" ram horn manifolds. 4spd with 3.31 gear and 27" tire.
looking for the best torque i can get in low and midrandge. Something that optimizes this combo. sound would be nice but i basically want to avoid all the issues that big cams create.
something to avoid the lugging or chugging when pulling in parking lots. or low speed in higher gears... in a 61 vette
looking for the best torque i can get in low and midrandge. Something that optimizes this combo. sound would be nice but i basically want to avoid all the issues that big cams create.
something to avoid the lugging or chugging when pulling in parking lots. or low speed in higher gears... in a 61 vette
It's a simple matter to stroke a 327 to 350 CID by swapping in a 350 crank. Any 350 block can be stroked to 383 CID, but the '66 block you are planning to use has less rod clearance than the 350 blocks and a few specific 327 blocks. Still, you could stroke the '66 block to 370 CID with the correct choice of rod.
Attached is an article I wrote about stroking a 327 to 383. I have more info on this topic if you decide you would like to do something like this.
Another thing to consider is to buy the new Trick Flow "DCH" heads that have the external appearance of the vintage "fuelie" heads.
With displacement of 370-383 CID, stock '66 Corvette heads, and the L79 cam, you could easily make 400 ft-lb torque at 3000 rpm. That would light the tires any time your dad wants to show off. If you upgrade to the Trick Flow heads, the peak power will increase considerably, but will be limited by the factory dual quad intake.
My point here is that based on your stated goals, simply stroking the engine to add displacement will pay off very well in terms of torque-per-dollar.
