Stock Chevy 350 cam suggestions please

[metriccar]

I tried the Comp 12-646-5 and it was an improvement. It is good after the first lap where momentum is up, but on starts/restarts, I'm still a little slower than I'd like. I was actually thinking of trying the 12-647-5, which was actually for exhaust headers, when I have exhaust manifolds. The reason I want to try this is because the 12-647-5 has shorter duration on the exhaust. It's 238@.050 on the exhaust vs. 240@.050 for the cam I have now. Intake lobes appear to be the same for both cams. 236@.050. I was actually reading up on this and there seems to be conflicting opinion on what is better in certain applications. When running restrictive exhaust manifolds, and striaght pipes, should we be running single pattern or shorter duration to prevent contaminating the intake charge, or run longer duration to "help the exhaust get out of restrictive ports." The engine runs 5,000 RPM coming out of the corners up to 7,000 or so. But starts can be like 3,500 or so. So I'd like to improve the 3,500-5,000 RPM performance, without hurting the performance up to 7,000.

[induction apprentice]

Although there very well might be a better cam out there. My opinion is you are putting too much emphasis on cam dynamics and not enough though into the rest of the engine and car combination. There are many other places in the engine you can find low to mid torque in and gear ratio's, tire sizes, even corner weights can effect how it excellerates out of a turn. Someone gave some great advice in one of the first posts in suggesting backing off the lash. For a few test laps. That is just as good as putting a smaller cam in. I've gone as loose as .040" in the past when ever I felt an engine was over cammed and I wanted to see how it would respond to less intake and or exhaust timing. I am just saying it would have been a good test before purchasing something else. But your whole problem could be a saggy Q-jet or a open spacer killing off the signal strength you would have with a divider sealed right to the bottom of the carb? I am assuming you have to run a factory cast dual plane? Have you tried adjusting the spring tension on the secondary air valve? they are more often than not to soft. especially when they get old. Or try different metering rods. Q-jets are a " solid fuel " carburetor. They have no rear boosters. They respond like crazy to the correct metering rods , air valve tension and intake manifold. controlling fuel distribution with them can be a real art. But they are one of the best working carburetors on the planet when set up correctly. Also, the correct valve job can make all the difference in the world too. If you are running aftermarket int manifold? You may want to look down the plenum and see if the ribs are on the floor like a factory one. They where put there from g.m. to work with the solid fuel boosters in a q-jet. Without them your lack of torque could be as simple as fuel puddling on the plenum floor?

Anyways, you have a tough road ahead. that's what makes racing so appealing. If it were easy no one would do it.

good luck! induction apprentice, Tom

[cv67]

I'd return the Comp and buy Mike's cam.

x2

and dont even waste your time with those lazy factory GM cams.