hey guys, i know this is Team Chevelle but i'm tring to find an unbiased opinion toward a cam choice for my corvette actually.
the motor is an 11 to 1 327 with the rams horn 2.5 inch exhaust manifolds and full 2.5 exhaust out the back. the car is a close ratio 4speed with 3.7 gears.

it currently has the stock fuelly camelhump heads and an LT-1 solid lifter cam.

The car is originally a 327-365 (which would have had the Duntov 30-30 in it) so part of me wants to put that back in to keep her a stock 60k original mile car. (everything else is original aside from some suspension parts)

but I also have this other set of ported and polished camel backs and have been thinking of switching to a solid roller or a more agressive solid flat.

but it has to achieve two things... 1st of all, it must have as rumpety an idle as the 30-30 so hat is keeps its appearance as the big motor of the year,

and if I don't use the stock cam, i want it to be much more fun than the LT-1 cam is. I will be keeping my cast manifolds on and it does have the aluminum intake so those restrictions exist.

I know there is the value issue of keeping this perticular car stock, but yet I like to drive it and have fun, and the LT-1 cam just about sucks with my combination.

Any thoughts??? just for instance If I don't go stock, I was thinkng about the ISKY solid roller 201575/570 which is a custom solid roller that both Ron and Wolfplace reccommended. I don't recall the exact specs but it is about 244 and 251 @ 50 with like 282-288 adv, and 575-570 lift on a 108.

Harold also reccommended the Lunati 401A6LUN cam which is a solid flat cam with similiar specs but much less lift on a 110.

The big thing is that I drive this car quite abit and my wife and I take some fun drives with it and i'll often have her drive so the motor must be driver friendly especially at part throttle driving which is where the car is 90% of the time.

what are your thoughts?

thanks

Aaron

The two best small block cams I have ever tried are a comp 280 hydraulic flat tappet (480 lift, 230 dur. at .050) and a comp 280 solid roller (I think it was the same dur. but with .550 lift. They both rocked and were completly streetable.

Been a long time since I messed with one of these, but if I am not mistaken, the factory 365/375 HP cam has fairly short seat timing (for the day anyway) and big lash settings - like .026 or so. Why not go with one of the more modern tight lash cams, keep the lift in the .500 range or below. You may want to run a later LSA also, out around 110LSA just to control detonation. Wish I could tell you the solid cam we had in the 327 in the '56 way back, basically was the same motor - 327/350hp but with a solid instead of the hydraulic. One thing for sure, those motors are a real 11.0/1 compression and will detonate if the cylinder pressure gets too high. Good luck.

For a true 11:1 327, about the smallest cam you can use and not get into detonation problems is a 290º adv dur on 110 LSA and installed at 106 (4º advance). With a single pattern, the overlap is 70º which will sound pretty lumpy. Not using headers, although your manifolds are very good ones, you might want a dual pattern.

These are the valve timing overlap ranges that are most likely to work correctly (thanks to David Vizard for providing this):
trucks/good mileage towing 10-35 degs overlap
daily driven low rpm performance 30-55degs overlap
hot street performance 50-75 degs overlap
bracket/oval track racing 70-95degs overlap
dragster/comp eliminator engines 90-115 degs overlap

As you can see 70º overlap is a lot. A dual pattern will increase overlap and idle roughness.

actually the 30-30 has a very long seat timing.

advertised specs are like 346 which is not entirely accurate becasue they had extremely long clearance ramps so quite a bit of that duration is taken up in lash before the valve even opens.

after talking to several people,

i'm either gonna run the Lunati Grinds by harold,
either the 401A6LUN or the 501B1 Solid roller.

i'm just trying to decide if the roller lends any significant torque at lower rpms where I need it in everyday driving.

Right, the ramps are long, but the wide lash eats up quite a bit of duration. On a solid, the net effect is where the cam is at "0" lash. Either,way I am sure you will be in good hands. I tend to think the cam we ran way back in the 327 was a Lunati.

A 30-30 cam is 254 duration at .050!!

I do from personal experience know that a good old-school, Isky Z-30 runs GREAT in one of these motors!!

My long gone Crippled Buddy's real '64, 375hp/327 Fuelie motor was STILL pulling at 7,200 rpm with no more then the Z-30 and his 2.5" dia, 6" long pipe nipple dumps open right straight down below his ramshorns where the exhaust pipes started their 90 degree bend to the rear!!

He, He!! We were running between 160 and 170 for like 8 miles or so way back in the mid '60's late one night!!

pdq67

No doubt cams have come along way from the old factory grinds. I would run enough duration to allow it to run on pump gas and no more. My thought is the rams horns are going to somewhat limit your top end, so put in a cam that is big enough to give you the sound and be gas compatable (still pretty big for a 327), but still retains as much low/midrange power as you can keep.

Just as a point of reference the old 30-30 Duntov specs are :

Lift........... .485

Dur @ .017 ......346 deg

Dur @ .020 ......314 deg

Dur @ .050 ......254 deg

LSA .............114 deg

Lash (hot)........030 and .030

As you can see it does have real long clearence ramps.

For what ever it's worth I have known 3 different people who have used the GM "178" LT-1 cam.... and everyone of them disliked it.... It seemed to RPM but just didnt accelerate the car as well as the earlier 30-30 Duntov did... or for that matter the much smaller 097 Duntov did...... Haveing the LT-1 ground on a 116 LSA certinally didnt help any either.....

Mske that 4, if you include me. LOL

I'm not being sarcastic, but The resident expert at the Corvette Forum raves about the LT-1 and has every test to prove it. While I am astounded at his knowledge and expertise on the subject, and wouldn't argue with his logic,numbers, or research, my experiance with the LT-1 cam and the Duntov 30-30 don't seem to compare. My stock Z-28 302 with manifolds,smog, and same gearing in a heavier car pulled noticably harder with the 30-30 than my 327 with the LT-1 cam.

I don't know if there is something magical about the 302 that is just works better, but neither my 302 or my 327 in the vette do much of anything below 3500 but when the Zmotor came on the cam, it rippes much better than the 327 does with the LT-1 cam, and the Vette has better exhaust, 25 more cubes, and it weighs less, so you would think that with those attributes, it would more than make up for the smaller intake lobe of the LT-1.

I personally think the 178 LT-1 cam is a dog. In a 383 or 400, its probably killer, becasue of the torque and 116 LSA seem to work well, but it ain't doing it for me.

I'm guessing that going to the 30-30 would be a nice improvement and bring the car back to stock specs, but as long as i'm goin in for a cam change, i'd liek to get as much usable power out of it, while still being able to run 94 octane fuel, and have the rumpety idle.

Also, regarding the LT-1. I believe GM designed that cam to work with an air-conditioned 350 with automatic trans combination.

Just that alone should tell you that it is a tamer camshaft.

Also, the prototype LT-1 motor that was first installed in a 69Camaro, was a 350 4-speed with the 30-30 cam, and that is where they got the 370 Horse figure from.

So the 1970 LT-1 published specs I believe were from that very 350 with the duntov 30-30. Once they reasoned to use the motor with AC and auto trans, I believe they deliberately reduced the intake duration of the cam, and widened the LSA to 116. That would be enough to run an auto trans and AC in a bigger motor.

I have to agree with much of what you say... GM wanted the 2nd gen Z28 to be a more civilized car than the 1st gen Camaro's were.And to me they did achive that.

Much of the need for the cam redesign was for those very reasons and the increasingly more stringent emmissions laws....by 1969 most everyone in Detroit knew the handwritting was on the wall with respect to emmissions.... But the LT-1 or the most part just never seemed to quite match up with the earlier cars even in 4 speed trim..... Certinally the second gen cars weighed more than the 1st gen but.... oh well.

I was never a big fan of the 30-30 Duntov but if given a choice between the two I'd take the 30-30 over the LT-1 cam anyday.Back in the day the 30-30 was VERY popular and sometimes despised by those who didnt know how to live with it... But to me regardless of what engine it was in..... (383's back then meant Mopar ) 383 Chevys were not something you saw alot of.... but the 30-30 just didnt really come on hard till 4000 RPM... but from then on it got with the program.... That was one of the reasons I prefered the 097 to the 30-30 for most everyday driveing with above average performance.... In " My " 331 11-1 461's Z28 intake 4 speed 3.90's.... the 097 pulled 15 in of vac and came on hard from 2800 RPM up...I spun mine 6800 RPM..... The 30-30 in every other car I knew of pulled 12 in of vac and was dead under 2000 but from 4000- the 6800 to 7000 range ripped.
But in nearly every case the 30-30 had trouble beating the 097 in actuall acceleration....and the LT-1 cam just seemd a distant 3rd in comparrison.
And for it's day the ancient old 097 was as good or better than any hi perf OE GM cam that came after it.... including the L-79 stuff.But thats just my opinion....

That said I agree that any good aftermarket cam would easily trounce any of the old GM grinds..

I'd use one of the solid flat or rollers you mention, but would have it done custom on a 112 or even a lazy 114 lsa to ensure the bottom end isnt too raggedy and to drop your cylinder pressrue in a true 11:1 motor. Comp 280AR on a 112lsa seems about right.

Ditto the little-bitty -097 cam as being one of the GREAT ones, imho too!!

Loved it in my old junk 301 up 'til the points bounced.....

And fwiw, the Isky Z-30 I mentioned is 290/250, 108/108, .480" gross lift and pulls like a freight-train once you get her "up on the pipe" as the 2-stroke crowd talk about!!

pdq67

the Z-30 looks cool, but i'm sure its more in the vein of the old 30-30... slower ramps, long duration, small lift.

the ISKY Solid roller I'm looking at getting is
280/290 240/246 (@.050) with .525/.531 lift on a 110.

in my 327, i'd think that cam would make much more usable torque than the LT-1 or 30-30 and should come on like a banshee at about 2500-3000 and rip hard till 6200 or better.

even with my manifolds, i'd bet that cam would kick serious ass.

6200?? Man, you're not thinking 'big' enough. A cam like that would be good for near 7000, or more in a lil ol 327. Can Isky do you once size smaller on the SR and set it out on a 112? It would certainly still give a lope, yet give a much more useable power than the 4000 rpm "on" switch of the lt1 grind. As Pat alludes to, you *might* have some pump gas issues due to the cyl pressure.

What does Mike think about the smaller RR490, but done custom on a 112 lsa to handle the compression?

I agree, it should rip higher than 6200, i just don't want to break ****.

you think that cam has enough overlap to run the 11 to 1 that my motor supposedly is?

Mike Lewis and I were talk ing about the real compression being nearer to 10 to 1 but depending on the head gasket it could get closer to 11.

if I ever sell the car, i want to put the stock 30-30 back in so 11 to 1 is probably where I need to be.

so....

Like I said, the old-school Z-30 solid Isky cam is a "Thumper" in a 365hp/375hp/327 motor!!

OK, call Ron Isky up direct AND ask him what to use??

And fwiw, I'm scared to death to run a solid roller on the street b/c of losing a lifter axle and needle bearings!!

And I want the extra hp too!!

pdq67

Originally posted by aaronz28:

the ISKY Solid roller I'm looking at getting is
280/290 240/246 (@.050) with .525/.531 lift on a 110.

in my 327, i'd think that cam would make much more usable torque than the LT-1 or 30-30 and should come on like a banshee at about 2500-3000 and rip hard till 6200 or better.

even with my manifolds, i'd bet that cam would kick serious ass. We run a Camcraft 269°/269° @ .020", 240°/240° @ .050" 110° LSA .615" lift roller cam in our 64 Nova road racing 331" 2-bbl setup. Tremendous torque from 3000 to 7000 rpm. This setup made 355 rwhp @ 6600 rpm with a stock 500 cfm 4412.

One thing I notice amongst racers, at least where I race. The majority of small block street strip cars run comp 280 cams, Holly carbs, and Victor jr. manifolds. In my 327 I ran a 280 comp cam, 4.11 gears and 3000 stall with 10:1 compression. I ran regular pump gas(not premium). IT was a daily driver for many years. 1.81 60ft, 8.20 1/8, 13.04 @ 103 1/4 . the heads were slightly ported 461s. 3770 race wt. Im not a cam expert but certain combinations work and the word gets out. And like I said before the 280 solid roller rocks too. I ran that cam with Iron heads, and 11:1 compression on 92 octane. 12.50s in same car no problems. It was Violent! And you can turn them a lot higher than 6200 rpm.

are you guys running headders?

becasue I plan to keep my stock manifolds, (for appearance, and I'll never race the car)

but none of the cam manufacturers do tests with Manifolds, and there might be some truth to the old grinds being superior with OE manifolds only.....

any thoughts there?

again,

i'm just trying to find the cam that will make the most power everywhere with the stock manifolds.
While they are stock, they are the cats meow for cast manifold class, because they are the center dump ramshorn, and they exit at 2.5" and run 2.5 all the way out through the back of the car.

i'm also concerned that it is completely drivable and not herky jerky like some cars with a cam that has too tight of an LSA

i've also read that backpressure and tight lobes contradict the benefit of each other.

just foor for thought.

What about the famed UD 288/296 solid FT cam?

It would work well with your compression ratio, although it would probably be a bit rough on the street. Not sure what effect running it with manifolds would have.

but none of the cam manufacturers do tests with Manifolds, and there might be some truth to the old grinds being superior with OE manifolds only.....


There are several manufacturers that make cams specifically for motors with iron intakes, heads and manifolds. We have a 331" test motor that runs a Comp 12-620-5 cam specifically recommended for these type motors. It's also called the 263MAS-6, 236°/240° on 106° LSA.

If you're interested in maximizing your exhaust system for cast manifolds, read up a little here:

http://www.castheads.com/exhaust_manifolds.php

what kind of numbers does that 331 test motor put out?

is that a solid flat, solid roller? hyd? etc.

thanks

and I'm gonna order up a set of Brezeznskis for my car as well. that should help.

thanks

Aaron

The test motor made 330 rwhp @ 5900 rpm with a 2-bbl carb, SPII heads, and 1-5/8" headers. That equates to about 390 fwhp as installed in the car.

http://www.compcams.com/Technical/Search/CamDetails.asp?PartNumber=12-620-5