hey guys!
hope yall can help me! i have a 429 with a
comp cam 280 magnum cam! double roller timing chain is
set straight up! the problem is when i plug in the vaccum
advanced the engine starts to pop through the exhaust
and dies! if i unplug the vaccum advanced it seems to run
fine! timing is set between 10-12 degrees btc! please any
help!
thanks, terry !!

 

it should do the opposite, thats kinda strange, are you using a constant vacuum port or a ported one, a ported one only has vacuum under throttle, that might be your answer.........also go over your plugs wires and firing order again, you might have two crossed or something, my friends 460 acted that way and i found that #7 and #8 were backwards.......

 

i will check to see if i have any wires crossed
when i get home! i have a holley 750 cfm and
tried both vaccum ports! to and bottom! thanks
for the info!

thanks, terry !!