how much justice will i do myslf simply by adding a 4bbl intake manifold and carb to my well running but not really strong 1971 302 with 135,000 miles on it?
i would really think you might see a little. you'll probably mostly see an increase in gas usage. unless you add at least a cam to the package. maybe some headers. i don't think you'll be really happy unless you add a complete package. one part without the others is a mismatch. then you'll forget about the gas loss.
Don's right. Everything should work as a team. I think you should do a 4bbl swap, but plan on headers and a good 2 1/2" dual exhaust system. A comp 268H cam & lifters, dual roller chain, that'll put some grunt back in the old 302. exhaust manifolds suck, plain and simple. So does single exhaust, unless it's a 4" system with a 12" tip and 6 Jersey Torches out the back...propane fed of course. Yes, I AM being an idiot.
I believe with 135000 miles on it, I'd go ahead and get new rings, bearings, and the heads reworked, then add the cam, headers, and 4 barrel while you're putting it back together. A fresh engine will give more HP and you won't have to worry as much about the performance parts putting too much strain on the allready worn rings and bearings. Just my .
