Expert: Robert Summers - 12/10/2007

Question
I bought an old 69 Chevrolet truck with a 1974 400 block lt4 (T0121CTX) (330817) someone has put a cam in it, don't know what. what should the timing be set on? Runs real rough, and it burns real rich. has a new Holly 650 4bl. What do I need to to do to get it to run properly. I put a vacuum gauge on the carb to adjust, but doesn't seem to change the vacuum any.

Answer
Hi Ty... without knowing what cam you have that would be just a guess...here is a way to time it and get it close...put truck in gear and with someone in the cab holding the brake bring up the throttle, while doing that turn the dist one way slowly till it pings then the other till it pings as well then turn back the other way till your in between the two pings. that will get you with in a few degrees..also check to be sure you have that dist on ported vacum. that means no vacum at the vacum port till you give it gas.make sure that advance pot on the dist is working as well....hope this helps...merry christmas