I have a problem where my engine will bog down and often spit back through the carb under light to moderate acceleration. I originally thought it was due to an old TBI system I had. But I replaced it with a carb and still have the same problem! I even put 'richer' accelerator pump springs in the carb. I was wondering if maybe it could be my distributor vacuum advance not working properly? Or maybe a leak in the intake manifold? I installed a air fuel ratio meter and as soon as I put the engine under a slight to medium load it leans right out.

82 Z28
mild 350, Edelbrock performer intake, Edelbrock 600 CFM carb, Mallory unilite distributor, 700R4 w/'stock' converter, stock rear end.

Thanks.

 

Whats your timing curve look like?

 

Sounds like an intake leak. Get a can of starting fluid and start spraying any place the intake could leak while the engine is running. Also check vac hoses for cracks.

 

I installed the cam straight up and set the timing around 8 degrees.

 

I took my distributor out and checked the advance mechanism. It seems to work hard, not sure if that's normal. I put it back together and used manifold vacuum instead of the ported vacuum. The load bog is much better, but I think I missed when putting the distributor back in cause it starts hard like too much advance. But this tells me it's definitely a timing issue.