69 motor rebuild finding a cam

[Calvin C.]

I am now rebuilding the 350 for my 1969 corvette. It will be a numbers matching car, driver. The original motor was a 350 hp motor, heads and motor are original. I want To put a roller hd cam in the motor and have between 350 - 370 HP. Can you make some suggestions on which cam might work.


Thank you
Cal

[Joe C.]

Re: 69 motor rebuild finding a cam

What's the advertised compression ratio: 10.25 or 11.0?
You realize that this change requires screw in rocker studs with guide plates, and very likely enlarging the spring pockets.

[Calvin C.]

Re: 69 motor rebuild finding a cam

I will be built to 10.1 - 10.2

[Mike F.]

Re: 69 motor rebuild finding a cam

These links may help. I believe the original iron intake manifold will limit you closer to the 350hp(gross) mark.

https://www.forums.ncrs.org/showthre...-L46-Dyno-Runs

https://www.forums.ncrs.org/showthread.php?97746-L-46-Dyno-Runs-Part-2

https://www.forums.ncrs.org/showthre...no-Runs-Part-3

https://www.forums.ncrs.org/showthre...no-Runs-part-4

[Calvin C.]

Re: 69 motor rebuild finding a cam

From the Dyno's listed 370hp with 10.1 compression and stock heads and manifolds isn't happening. Ultimately I want good power, stock sound, and drivability. I thought a roller set-up may get me a little more cam and not sound too wild. I couldn't find a roller set-up in those dynos?

thanks
cal

[Gene M.]

Re: 69 motor rebuild finding a cam

A roller cam in the old unmodified engine is a waste. As Joe says a roller cam alone is not realistic.

Just clean up the heads and flow them out will give the best return on HP.

[Calvin C.]

Re: 69 motor rebuild finding a cam

I can see your point, a roller set-up with no power gains in itself is not a good value, however it may not be a waist, which is why I was asking to see if anyone has tried it. I have had better luck with slightly modified motors running a roller set-up, never a flat cam issue for instance, as well as better numbers. But not big gains just by changing to a roller. Sounds like it's not dollar wise though.thankscal

[Duke W.]

Re: 69 motor rebuild finding a cam

How much time will it spend above 5000 revs?

Is power at 2000 - 3000 revs important to you? How about fuel consumption? How about the idle behavior - OE - or typical aftermarket hot rod cam.

The best thing you can do to a L-46 is massage the heads, use all OE equivalent replacement parts including the cam, and optimize the spark advance map. Limit compression ratio to 10.5 max, and this should be attainable with the OE replacement pistons.

There are many threads on restoring OE engines for "more power" and revs without screwing up the idle behavior and killing the low end torque and fuel economy, and SHP small blocks yield 270-290 SAE corrected RWHP with the OE manifolds, which is 350-370 SAE gross on a lab dyno. The "secret" to top end power is head flow, not the cam, and substantially more average power (but not top end power), is available across the entire rev range by increasing stroke.

Engines are not one-dimensional as in maximum power at the top end of the rev range. For a road engine, broad torque bandwidth is what makes the car responsive and quick.

One issue with '69s is the 2" exhaust system; 2.5" pipes are probably worth 10 RWHP on the top end.

Duke

[Calvin C.]

Re: 69 motor rebuild finding a cam

All good advice
thanks
cal