Rebuilt 351 Windsor with stock 4bll intake, Edlebrock 600cfm. Okay I am on my third cam installation. I first tried competition cam 270 duration 512 intake, 517 exhaust--- no go after about 30 miles it started sputtering if I gassed it just a little bit to much, running hot. Second try, I made a mistake looked at the duration wrong, I said what the heck try it anyway. Put new lifters in, 272 duration with 484 lift both sides, same situation, I drove it around for about half day, cruising, did great had a harder lope than the first cam. Then it happened, sputtering if I gassed it just a little to much, sputter,sputter and running hot. So my third round is near. I dropped way down, the smallest but biggest I could find where specs show this is for stock heads and small ports. its a 255 with 250 lift- duration with a 434 lift on intake, and 467 on exhaust. exact cam.Cams 35-416-3, so am nervous and annoyed. Hope this solves my issue. What do you guys think?