this is probably one of the most asked Q's, but here goes:

I've got a non matching number, mid 80's, stock chevy 350 in my 63 vette. its got headers, edelbrock alum intake and matching carb, also HEI and auto transmission.

I got the motor for free and don't really care what happens to it, other than that it provides thrills when i push the gas pedal down.

the big Q: I've thought about putting in a cam to liven things up, but have no experience in this endeavor. I can get help with the mechanics as needed, and wouldnt cam it up to the point it's streetability is lessened - but must wonder:

Will the cam make a huge difference in power? is this improvement alone worth taking apart an engine that's running well and making a fair amount of power?

So guys, what does the voice of experience have to offer??

THanks :chevy

 

Increasing horsepower refers to the peak horsepower that the engine produces, which is available at one speed in each gear, assuming it can reach the power peak in top gear.

You actually use the engine across the rev range from idle to peak revs and most of your time will be spend in the lower to mid rev range. For this reason you want to pick valve timing that gives you a useable torque curve that is matched to your driving rather than picking some peak horsepower number out of the sky and finding a cam that will achieve it. For every increase in top end power you will loose and equal if not more power in the low end of the rev range, and at some point you end up with a stone.

For a street high performance engine you should select a cam that provides 80 percent peak torque bandwidth that begins no higher than 2000 RPM. For a mild cruiser engine that should be lowered to 1500 or less.

There are literally hundreds of aftermarket cams, but my preference is for the OEM cams from the fifties through early seventies. You will get about as many opinions as there are cams, so you're best bet is to buy an engine simulation program, learn how to use it, model your existing engine components and then start modeling different cams until you get the torque bandwidth that you select ahead of time as a design requirement.

If your 350 is a base type engine with the 929 cam, you will really wake it up with the L-46/L-82 cam - 3896962. You'll also need to change the vacuum can on the HEI to match the cam and a bit higher stall speed on an automatic will also help.

You didn't say what kind of automatic it has, but if it's a Powerglide, I would definately recommend a swap to a four-speed if you go with a high performance cam. With only two speeds, a Powerglide needs to be driven by an engine that is biased toward lots of low end torque, which your current engine probably has.

Duke


[Modified by SWCDuke, 6:21 PM 7/11/2002]

 

You the man Duke, I read some of your other cam posts and appreciate your input.

I think the coming winter project might be to go with a hotter old-school GM cam like you said.

its a 3 speed auto BTW