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72 corvette heads, manifold, and camshaft questions

General engine tech -- Drag Racing to Circle Track

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sowen57
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72 corvette heads, manifold, and camshaft questions

Post by sowen57 » Tue Nov 19, 2019 10:56 am

Gentleman, I am in the planning stages for an engine for my, weather permitting, daily driver corvette. Here is what I am considering but I need some guidance in certain areas. I would like to build a 383 from a late model roller cam block, I would use a Scat 9000 1 piece seal crank for 6 inch rods, the scat 6 inch 7/16 rod bolt rods, and either the Mahle 1x1x3mm reverse dome piston or the SRP 1.2x1.5x3mm pistons, would like to stay with a 4032 material piston for a little tighter piston to wall clearance. 1st question is will this proposed rotating assembly internally balance? I am leaning toward the AFR 195 heads in either the street or race port configuration, and because of hood clearance issues I believe I can only use the performer type manifold not the RPM series, and I also want to retain a Quadrajet carburetor. What derivative of the low rise manifold is best? Edelbrock, Weiand, Chinese? And can it be ported enough to warrant the use of the above AFR heads or since the restriction will be the manifold is it a waste of resources to use that head when there are less expensive alternatives out there. As far as camshaft is concerned I am leaning toward the Vizard school of thinking and considering something along 219/225 duration at .050 on a 106LSA installed at 102ICL angle. Or if I am out to lunch please make any suggestions you see fit. Again this is a fully optioned corvette with 3.08 gears, ac, cruise, ps, pb, and automatic transmission. Not really looking for the cheapest build, just the right build given the vehicle parameters, the only time it would ever see a drag strip is just to see how fast it will go mph wise since it is totally a street car, I would guess the car probably weighs 3700 or so pounds. Hope I have given enough info, and appreciate all your responses.

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Re: 72 corvette heads, manifold, and camshaft questions

Post by mag2555 » Tue Nov 19, 2019 12:09 pm

Well your kinda on the right track, but those 195 heads with only a 3.08 rear is going to kill you, I would go for 180s or mildly ported 170s.
If your hung up on running those 195 heads then you might as well try to yank out the most top end hp an some ok drivability, which means going to a Weiand single plane of the old style which I believe will fit under the Vetts hood, but rework it by welding 1 inch long runner divider extensions in the Plenum.

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Re: 72 corvette heads, manifold, and camshaft questions

Post by 75vette » Tue Nov 19, 2019 12:18 pm

A performer RPM should fit under your hood with a drop base air cleaner. At least it does on a 75.

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Re: 72 corvette heads, manifold, and camshaft questions

Post by F-BIRD'88 » Tue Nov 19, 2019 12:31 pm

Does your 72 Vette have the LT1 hood or the flat hood?

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Re: 72 corvette heads, manifold, and camshaft questions

Post by sowen57 » Tue Nov 19, 2019 1:17 pm

Flat hood, keeping a Qjet, and stock type air cleaner.

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Re: 72 corvette heads, manifold, and camshaft questions

Post by Little Mouse » Tue Nov 19, 2019 2:17 pm

How much compression will you end up with using reverse dome pistons ? Assuming your going to use a flat tappet cam with that duration you won't have lots of lift, I think in that case you should use afr 180 head or if you prefer to save some money profilers 180/185 runner head.

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Re: 72 corvette heads, manifold, and camshaft questions

Post by sowen57 » Tue Nov 19, 2019 2:24 pm

9.8 compression, hydraulic roller cam, rocker ratio to effect lift needed.

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Re: 72 corvette heads, manifold, and camshaft questions

Post by sowen57 » Tue Nov 19, 2019 2:29 pm

Not asking to save money, but if the flow of the 195 AFR heads cant be used because of the intake manifold limits, then what's the point? But if there is a low rise dual plane that won't be too much of a restriction or can be ported to remove the restriction or lessen it sufficiently, then I will gladly invest in the better heads, I will even purchase the competition versions if that helps.

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Re: 72 corvette heads, manifold, and camshaft questions

Post by lefty o » Tue Nov 19, 2019 4:07 pm

my opinion is that you are looking at a mismatch. cam is in a decent ballpark for what you want, going to need a little more gear, and while the afr195 is an excellent head, its more than you need.

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Re: 72 corvette heads, manifold, and camshaft questions

Post by F-BIRD'88 » Tue Nov 19, 2019 5:29 pm

No mention of the. Exhaust system. If both the in and ex are restrictive the afr heads will be a waste.

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Re: 72 corvette heads, manifold, and camshaft questions

Post by F-BIRD'88 » Tue Nov 19, 2019 5:41 pm

I'd look for a aluminum head that is much like a 170cc port vortec head, shorten up the cam and give it more cr.
10.4:1 ish. 92 octane unleaded.

Eddy Etec170. Trick flow 185 head, Ported GM 113
afr180 The 106lsa cam will not return a torque advantage unless the exhaust on the car is free flowing and very active.
Ported 062 Vortecs would work well.

You should measure the current carb-aircleaner to stock vette hood clearance to see what is possible.

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Re: 72 corvette heads, manifold, and camshaft questions

Post by F-BIRD'88 » Tue Nov 19, 2019 6:22 pm

A single plane low rise intake to consider.
Weiand Team G #7525 "street ram"
3.5"-4.5". Carb pad height Alot easier to port the %&$- out of this than a dual plane...
Use as much carb spacer as allowed by room.
Consider custom modding the air cleaner for more clearance. Its just sheet metal.
Consider a plenum divider with that Qjet carb spacer.

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Re: 72 corvette heads, manifold, and camshaft questions

Post by mt-engines » Tue Nov 19, 2019 10:27 pm

wow.... lots of great advice here. :roll:

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Re: 72 corvette heads, manifold, and camshaft questions

Post by sowen57 » Wed Nov 20, 2019 4:14 am

The car already has long tube headers, 2 1/2 inch mandrel bent exhaust, x pipe and walker dynomax mufflers. I hope to have the engine pull to 5800 to 6000 rpm. I will change converter to suit camshaft. I have had other cars with 230 degree intake cams and they would not produce enough vacuum for all the accessories on this engine. looking to try and make 450 or so hp and torque. Thanks for the suggestions so far. Does any one know if the L88 style air filter will fit on a Q jet?





















q jet

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

Post by sowen57 » Wed Nov 20, 2019 4:26 am

My understanding is the 1975 corvette has about an extra 1 1/2 of clearance. This will be a hydraulic roller cam. One of the reasons for using the late model block, so lift should be in the .510 range and by using 1.6 or even 1.65 rockers then .540 to .560 lift should be possible?

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