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72 corvette heads, manifold, and camshaft questions

General engine tech -- Drag Racing to Circle Track

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Tuner
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Re: 72 corvette heads, manifold, and camshaft questions

Post by Tuner » Fri Nov 22, 2019 10:40 am

sowen57 wrote:
Fri Nov 22, 2019 9:47 am
I have the stock dual snorkel air cleaner, I may try to route cold air to the snorkels, also it has the tach drive distributor, which I will rebuild and convert to electronic ignition, any favorites Hays, Pertronix?
Pertronix 1181, the one with the magnets in the ring below the mechanical advance and rotor. The new 1181LS, LS = lobe sensing, is easier to install but has less dwell, so the regular 1181 is better at high RPM.
https://www.speedwaymotors.com/PerTroni ... ,5399.html

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Re: 72 corvette heads, manifold, and camshaft questions

Post by autogear » Fri Nov 22, 2019 11:30 am

Aren't the house-brand heads by either Jegs or Summit produced by Profiler? They should have a 180 head if you were willing to go that small. Buy em bare and have em loaded up with parts from competition products if you like; or just take the complete heads to your favorite engine builder to check the guides,seats, etc. Just make sure that the springs you use are appropriate for the cam you decide on. At your RPM, there won't be much gain or loss with any low-rise QJ manifold.

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Re: 72 corvette heads, manifold, and camshaft questions

Post by sowen57 » Thu Nov 28, 2019 1:52 pm

Can anyone tell me about the house brand Jeg's or Summit heads? What cross section size and valve size heads do I need, for this build to rev to 5800 to 6000 RPM? What about some cam recommendations for the 3.08 gears and TH400 I will buy whatever converter is needed for it. Do you guys have a favorite street converter builder? Not fond of TCI as they screwed me before and I won't spend money with a company that won't stand behind their products. I was wondering if the AFR heads would leave me some room to grow or would they really be too big for a mild 383?

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Re: 72 corvette heads, manifold, and camshaft questions

Post by BillK » Sat Nov 30, 2019 9:31 am

Belgian1979 wrote:
Thu Nov 21, 2019 4:50 am

What is the problem with an oil ring support on a street engine ?
Cant say for sure that there is but I prefer not to use them if at all possible. One more thing to move around and affect ring sealing even though the oil ring is not as critical as the others. Simply personal preference like I said.
Bill Koustenis
Advanced Automotive Machine
Waldorf Md

www.enginerepairshop.com

sowen57
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Re: 72 corvette heads, manifold, and camshaft questions

Post by sowen57 » Sat Nov 30, 2019 12:30 pm

Bill K, I agree as
Forrest Gump would say "one less thing."

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Re: 72 corvette heads, manifold, and camshaft questions

Post by sowen57 » Sat Nov 30, 2019 12:35 pm

Thanks tuner, 1181 Pertronix line along with their coil. Anyone ever use the crane unit and is it still available?

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Re: 72 corvette heads, manifold, and camshaft questions

Post by 77cruiser » Sat Nov 30, 2019 2:41 pm

I thought Jegs was selling Profilers with the Jegs brand on them. Used to be Canfield but they've been gone for a long time.
Jim

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Re: 72 corvette heads, manifold, and camshaft questions

Post by fly442 » Sat Feb 01, 2020 1:28 am

what number on heads

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Re: 72 corvette heads, manifold, and camshaft questions

Post by rebelyell » Sat Feb 01, 2020 8:49 am

Seems most 1-pc rms cast cranks that can internal balance require 6" rods because their counterweights have larger OD than 5.7" versions.

Seems just about anything can be made to internal balance; with enough $$$ heavy/mallory/tungsten metal and $$$ labor.

FWIW, all those OE 1-pc rms motors that are referred to as internal balance are (in reality) a hybrid; they have a neutral damper at front with a counterweighted flexplate-flywheel at rear.

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Re: 72 corvette heads, manifold, and camshaft questions

Post by Little Mouse » Sat Feb 01, 2020 10:59 am

sowen57 wrote:
Fri Nov 22, 2019 9:50 am
Thanks tuner that is an option just thought the performer would be a worthwhile upgrade, maybe 10 to 20 horsepower above 3500 RPM?
I saw an article done on the then new redesign of the edelbrock performer comparing to a stock iron q -jet manifold and q- jet carb on both manifolds, engine was a 355 around 10 compression comp cam just a good street engine. The performer made 9 hp difference at the most and 6 hp overall through the powerband, then it would be at least 15 lbs lighter then the iron manifold. I think it would work well enough for what your describing.

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Re: 72 corvette heads, manifold, and camshaft questions

Post by pdq67 » Sat Feb 01, 2020 1:13 pm

Fwiw, pick up a junkyard ALUMINUM Q-Jet intake and bull-nose it and bowl-blend the runners and bowl so it is opened up a bit.

Light weight and should do fine here.

Add no more than a good old CC 268/218 HE hi-cam and go!! It will do very well here.. If you want more cam then install a modern version of the old 350hp/327 hi-cam.

Might want to plug the smog ports in the intake if you want to??

And as far as STOCK, cast-iron 4-barrel intakes go, IMHO, the old 300hp/327 AFB intake is a real winner until the Z-28/Holley 300-36 type aluminum intakes came out. But they are taller though... The old AFB intake is low so should fit fine and run like a, "scalded dog"!!

pdq67

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Re: 72 corvette heads, manifold, and camshaft questions

Post by sowen57 » Sat Feb 01, 2020 1:43 pm

Thanks for the continued participation in my post fellas. The cam I am considering is 269/219 hydraulic roller from howards, so real close to the old HE comp cam. Also their seems to be some people who have made a performer RPM Qjet fit iguess I wont know till I try.

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Re: 72 corvette heads, manifold, and camshaft questions

Post by Little Mouse » Sat Feb 01, 2020 6:21 pm

Think you could pull off the rpm with the right air cleaner.

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Re: 72 corvette heads, manifold, and camshaft questions

Post by jeff swisher » Sun Feb 02, 2020 10:43 am

On a wheel dyno I tested some intakes and 2 carbs on those intakes.
The engine was 350" and 218@ .050 cam high compression sort of 10.87 I ran this thing to 6500rpm it made max HP at 5700 rpm.
You usually shift past max HP by 600-700rpm or so.. It would run to 7000 without nosing over or falling off 7200 was valve float.

Baseline was the Edelbrock Performer RPM intake, A much modified 4779 750 double pumper carb No choke and radiused and epoxied entry thinned throttle shafts small head screws in throttle blades. The other carb was a tuned Q jet 750.

Next intake was the marine Q jet iron..it has a slightly deeper floor and the runner entry off the carb pad is rounded not machined square and sharp like a Q jet automotive intake.
It made 30 HP less at the wheels than the RPM intake .
Another note is the 4779 made 10 more HP on the RPM intake than the Q jet did.
BUT on the Qjet intake the Q jet made 10 more HP than the Holley square bore 4779. Interesting.

Now the next intake was an automotive iron Q jet intake that i removed all the guts from under the carb.
It is now looking like an open plenum intake with NO divider and I blended the entry into the runners so it was rounded not square.

That intake made 10 less HP than the Edelbrock Performer RPM intake.

I did NOT port any of the runners or enlarge them.. there could be a couple HP there.
I do not like the Edelbrock Performer intake... mostly because I did some tinkering on a car with it and the RPM intake and it was a big turd and has what is to me a fail. A FLAT FLOOR.
I want a waffled floor something to keep fuel atomized.

Get out the grinder use a Q jet intake .. aluminum or iron.

Buddy used the same Ported Q jet intake on his 355" Tested against the RPM and a victor JR. and a hurricane and strip dominator.
This was a 252@ .050 cam and had 3500 stall 4.11 gears 800 double pumper.. he stated he thought the ported Iron Q jet felt slightly better than the RPM. and the victor JR was sold for 20 bucks after the testing.
The strip dominator felt best but was a loaner and the Hurricane was just slightly less on power production.
Hurricane intake stayed on.

No dyno numbers just days of driving and racing and tuning on that deal.
LT4 hot cam (sort of) is a really good one..I ran one in my 357" with ported 906 heads more RPM than you ask for 7000 on the shifts for me and 130 seat pressure beehive springs 313 spring rate.
But my LT4 hot cam is different with exhaust lobe profile on the intake side and on a 110 LSA

Stock is 218-228@ .050 and .492" lift with 1.5 rockers on a 112.
Mine was 228-228.
Used the same grind on an LS engine you get more duration at .050 with the 1.7 rocker and .557" lift.
In a 6.0 LQ 9 with ported heads and carb it revs quick to 7000 rpm.
Hard to hook to the pavement. Stuck that LS grind on a 109 LSA and cranking pressure came up 25 PSI over the stock cam.
No loss of low end there.

Fun to manipulate the lobes on cams if you have a cam grinder that is willing to do it.

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Re: 72 corvette heads, manifold, and camshaft questions

Post by HDBD » Sun Feb 02, 2020 1:16 pm

I didn't think your original plan was all bad. You can up the compression a little and use cam about 215° @ .050 and get there even with the stock carb and ported stock intake. Should land in the mid 400s and same for torque and idle smooth with 14" vacuum or thereabouts. Don't let the 180 heads scare you or the 6" rod. This will do everything and fit under the hood.

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