For some reason when im getting on my car, especially if i shift it by hand (i have an automatic), once i hit about 4500-5000 rpm the engine starts bogging down really bad, the only way i seem to be able to avoid it is if i roll the throttle on really smooth, i cant just stomp on it. it tends to be really embarassing to, especially when your racing someone, and all the sudden they just jump ahead.

Please help. Thanx in advance.

 

What engine?

What carb?

What modifications?

 

Wow, sorry about that, its a 355 with edelbrock performer intake and carb. it has regular manifolds to a 3.5 y pipe, no cat. and another thing is, that it doesnt always do it.

 

Sounds like hot fuel, since you say it doesn't happen all the time. Or, it could be weak fuel delivery, the best way to determine that would be to get a fuel pressure gage installed and see if it drops down under those conditions.

What kind of fuel pump/pressure regulation are you using?

 

it's just the cam driven pump on the engine, and there is no pressure regulature. but about the low fuel pressure, the car was originally a TPI car, and i believe that who ever converted it left the original fuel pump in the tank as well, although it isn't working because they hacked all of the wiring, could it cause low fuel pressure if the manual pump i have now has to draw through the old electric pump. Thanx in advance.

 

Like sucking a Big Gulp through a coffee stirrer...

 

Could it be a broken secondary spring in the carb? That'll cause exactly what you're describing.

 

If it does end up being the broken spring.....ditch your carb if you can afford it and get a carb with mechanical secondaries.