<BLOCKQUOTE>quote:</font><HR>Originally posted by XK1:
A compression test would tell you for sure about that. Before I had rebuilt my 350, I had put it in right out of the junkyard, and whenever i got on it and the secondaries opened, it gave a rapid pop through the carb. Sounded real neat, but it turned out the cam was flat and the exhaust valves were not opening, allowing the 'explosion' back through the intake valve. You might also have a valve not closing due to a bad valve spring??? I'd sure do a compression test if you haven't already. Thats a basic, first step that can eliminate a lot of things right off.
<HR></BLOCKQUOTE>yes I did do a compression test all cylinders where a 145 and 150lbs,and I checked to see if all rockers where going up and down about the same,it happens around 3000rpm,or under load.thanks for your reply.