Topic: How to tell - Intake or exhaust
in Forum: C3 Engines
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Former Member
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Canada
Joined: 10/17/2007
Posts: 39
Vette(s): 1980 Silver, L48
Totally re-built at 52,000 KM
Now 355 CI
Edelbrock Performer package
Dual exhaust
Hi all:
I am sure someone out there will be able to help and this is probably a stupid question but I appreciate any help you can give.
I took off my rocker covers to paint them and thought it might be nice to install a new set of Comp Cams Magnum roller rockers. - just a little extra HP on a stock engine. That along with a March underdrive should give about an extra 30 HP. I stayed with the Comp Cams Roller rockers as they fit under the stock covers.
I have the covers off and have read the instructions for the rocker arm installation and am pretty sure I can do the installation myself but I can't seem to find out with certainty which valves are the intake and which are the exhaust. I have the firing order and know the cylinder layout but not which valve is which.
Can someone help?
Thanks,
M
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Former Member
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Mounds View, MN - USA
Joined: 5/24/2007
Posts: 1031
Vette(s): 70 LT1 coupe, 69 350 HP coupe, 69 390HP 427 coupe, 71 LS5 convert, 85 coupe, 93 coupe
Identifying the valves is easy. The valve is in line with the runner of the intake or exhaust manifold. But even easier is to just remember EIIEEIIE, which is Exhaust, Intake... etc.
I don't think you will see a measurable increase in power with these changes. The underdrive pulleys will free up a couple of horsepower, but reduce cooling and charging efficiency. If you use higher ratio rocker arms, you will also see a very small increase. Neither one is really worth the expense unless used in conjunction with other engine improvements. You only have 8.5:1 compression ratio, and your heads do not breathe very well. Those problems, along with a very mild cam, limit what you can get out of this engine.
Larry
I don't think you will see a measurable increase in power with these changes. The underdrive pulleys will free up a couple of horsepower, but reduce cooling and charging efficiency. If you use higher ratio rocker arms, you will also see a very small increase. Neither one is really worth the expense unless used in conjunction with other engine improvements. You only have 8.5:1 compression ratio, and your heads do not breathe very well. Those problems, along with a very mild cam, limit what you can get out of this engine.
Larry
I agree, bolt on engine mods will not give you much in the way of performance increase, without changing the engine internals themselves. Headers will give you some increase, but you still need to improve the fuel/air that the engine draws to make a big difference.
in Forum: C3 Engines
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