I want to put a cam in my 5.7 350. Its all stock and want to replace cam, rocker arms, pushrods, etc. I was wondering whats the best lift for the stock heads?

 

i believe max lift would be .480

 

anyone else?

 

The max for stock castings is right around 0.480" but that varies with castings, so it's safer to stick to a 0.450" limit.
After that the retainers will hit the valve seals and destroy them.

You can extend that limit up to around 0.500" by swapping to different spring retainers. The stock retainers from a later model 4.3L V6 will give extra clearance.

Another issue is that valvesprings need to be upgraded for a more aggressive camshaft. You will have to measure to avoid spring bind, and piston to valve contact. You can generally get away with a lot there, but it's always best to measure.

 

How much power increase would .500 lift produce?

 

I would not run 0.500" on stock valve studs. Several years ago I pulled out several stock press in studs with the ZZ4 cam, .474"/.510". I would not risk it again.

 

Not very much extra over 0.450" lift unless you port the stock heads.
It is highly recommended to have the stud bosses machined down for screw-in type studs and guide-plates to run a more aggressive camshaft and upgraded springs.

A lot of people contemplate cam, lift, and spring upgrades without pulling, porting, and machining the heads to do it right. Some people do it and get away with it. Many run into problems and have parts damage. Either way you don't gain a LOT of power in comparison to a very mild cam ugrade and keeping the lift to around 0.450". The LT1 cam fits this description and used ones can be found pretty cheap. With luck and a good tune you might get an extra 20 to 30 HP with a good tune after the swap.

On the other hand if you pull the heads and port them yourself, you can then upgrade the valves (links in my signature) and run a much more aggressive camshaft to gain a very large chunk of power. By large I mean 50 to 80 HP or more depending on how far you go with the porting & camshaft, and the quality of the tune afterwards.

 

I want a mild cam to run 13's possibly high 12's with 373 gears

 

I looked at your page. I remember seeing your car online before. It looks almost exactly like my 86 did when it was all stock.

The performance and weight numbers on your cardomain site have to be wrong. Your race weight (that's with driver) is probably closer to 3600 lbs with a stock t-top car & auto.

You're going to need a good 330 horsepower to see 12.9 second ET's under ideal conditions. A simple low-lift cam swap with gears isn't going to come even close to that. In fact, with the long-runner TPI, I wouldn't even bother swapping your gears, even if they are 2.73:1 ratio - not unless you break your rear.

What you're going to need to reach your goal is a full porting and valve upgrade (ref - those links in my signature), or a good set of aftermarket heads, a pretty serious street cam, good headers, and a very good custom hands-on PROM tuning.
If it's done right you can have a very mild mannered engine, a low RPM cruise, and gas mileage at least as good as you have now.

For starters I'd recommend a set of stainless 1.75" primary tube shorty headers with 3" Y-pipe. I'd also recommend the LPE cam linked to in my signature. That's assuming the heads will either be modified or swapped before installing the cam.

 

I have not updated the car domain in a while. Car weight with driver is 3700 and I ran 14.6 with just exhaust. I plan on doing a cam kit with new intake with runners and the 3:73 gears