i'll try to reply to 2 posts here. the distributor is an hei in a 76 350 sbc. i have a retro fit roller cam 228 @ .050. 288 advertised. and i also have 4.10 rear. so maybe this setup will work. i do not think that i have the old springs, if i can recall, many years ago we played with the springs on my old distributor. i just bought this new distributor, it was set up with an adjustable vac advance. i will continue to test performance using both ported and manifold vacuum. it does not seem to idle bad, the cooler temps would be nice, but i don't expect to do a whole lot of idling. i think it's time to get things back together and let her loose!!! hopefully, i can answer the problem of gas getting into the manifold vac tube.