I had to switch from HEI a smaller distributor when I added AC to my 50 Chevy with a 250 due to clearence from the AC comp. The only other distributor I had was a marine type that had mechanical advance that I changed over to pertronix 2 and pertronix 2 coil. My motor loved it and felt like it added 50 HP. I feel like the big change was that the advance curve was better suited for my setup than the HEI, Havn't had the cap off the thing in 20,000 miles so I would say it has more than filled my needs..Jerry
