I just rebuilt my 396. It has about 200 miles on it. I the other day I took it a little higher on the rpm & at about 3,000 - 3,500 it pops out of the carb. This is with the secondaries opened. If I really ease slowly into it, it doesn't do it. Any suggestions? It was bored .030, COMP Roller Cam & roller tip rockers; 270/276 @.510. Edlebrock 750 CFM. I am hoping that the roller cam would have eliminated a flat lobe, but :confused:

Did it do it when you stabbed on the accelerator or just while you were running it at that rpm? One thing that comes to mind is the mechanical secondaries on the Edelbrock's opening up too early or giving a shock to the engine when they open up. That generally only happens right when you punch the throttle though. But that could explain why it doesn't do it when you ease into the throttle though. Just a thought. Only other things I can think of are tight valve lash, flat cam lobe, or overly retarded timing. :D

Good Luck!

I just went through the flat lobe blues on my buddy's car(I helped him with the installation!)
and I seriously doubt that you have a flat lobe
because it doesn't pop when you ease into it. Check your timing first and then the secondaries
as Malibu Man suggests. To be absolutely sure about the cam it's very easy to take off the valve covers and observe rocker arm travel while you're cranking the engine. Good luck! smile.gif

my '67 was doing the same thing...ease in to it it wouldn't do it, stomp it it would backfire through carb. It ended up being a vaccum leak at my intake...even though I torked them twice before. 3rd time was a charm.