1970 cutlass 350 bored .030, lopey cam, cold air intake, 10:25:1 comp, Holley 4150 vacuum secondary 650cfm,

At speeds between 25mph and 45mph if you attempt to hold those speeds to cruise the exhaust lets out a light pop pop pop pop until you wither eacclerate out of it or deaccerate out of it. Timing is a little advance with the 4:11 gears in the back, carb is tuned. any ideas?

 

What diameter exhaust pipes? Are you sure its not popping out the carb ?

 

3 inch, no defintly the exhaust and ive tried exhaut leak and new gaskets all the way to the collectors from the headers, ive tuned the carb best i can and the timing is as good as i think it can get.

 

It could be too much timing. My car is quiet but if I have too much timing it sort of bucks or hunts at a steady low load cruise. I'm not a expert but it would be easy to check.

 

If your carb is tuned and the timing is ok, maybe you have a loose baffle in one of the mufflers.