I just installed a 600cfm holley 4160 series carb onto my 12a stock port. I am running 62 jets in the primaries and a metering plate in the secondaries. I am using a 2.5" power valve with blowout protection installed. I also installed the 50cc accelerator pump kit. I am able to start the car if I pump the pedal a bunch and once it started I got my floats and idle-mix screws set to as close to perfect as I could possibly get them. My problem is that I am getting a really poor accelerator pump squirt. I have to pump the pedal a bunch of times just to get enough fuel to squirt in to get my car to start up. Then if I want to drive it I have to be very gentle on the pedal or else it just bogs and dies. Why am I getting a poor/no accelerator pump suirt when I throttle? Could it be a bad diaphram? valve or checkball missing? Any help would be great!

 

Well, I think I figured out the problem. I removed the carb, then the float bowl, then the accelerator pump and I found that the rubber umbrella check valve for the accelerator pump (below diaphragm) was off. The stem that hold it in place and allows it to function had broken. So now I have to wait until tomorrow when the part shows up and see if that fixes my problem.

 

Bumping an old thread- did that fix your problem?

I have an off-idle hesitation on my new-to-me '82 that I am trying to figure out. (When I stab the throttle, pulling away from an intersection or accelerating from a roll, it bogs and almost dies, then catches itself and gets moving.)

There's an aftermarket fuel pump on there now, and the seller (who is not the guy who put that pump on) postulated that it might be putting too much pressure to the carb and flooding the float bowls, so I guess when the accelerator pump squirts in it almost floods it out.

I think I am going to buy a fuel pressure gauge and see what's up there first, then possibly a fuel pressure regulator to keep things even.

 

Oh yeah, fixed it up a long time ago. I installed a 50cc accellerator pump and replaced the umbrella valve. Works great now.