Carb rebuild kit W/ synthetic acccel. pump?

[isaac_alaska]

Looking to see if anyone has a source for a carb rebuild kit that comes with a rubber or synthetic accelerator pump plunger, instead of the leather plunger. My truck has terrible hesitation when you give it throttle until it comes up to speed, and i'm trying to narrow down whether it's a case of not enough manifold heat, or accelerator pump not working properly. It's only been a year since i installed the new leather accelerator pump, but it did sit without being run for most of that.

Even a source for just the new accelerator pump would be good, as the rest of the carb is in good shape

thanks!

[isaac_alaska]

Follow-up question: is there anything that seals the accelerator shaft piston (not the plunger) inside its bore? my rebuild kit only had a brass piston inside a brass sleeve, is that enough to form the vacuum needed for accelerator pump operation, or is there supposed to be a thin O-ring on the plunger piston?

[RMS]

no O ring on the piston.....that I have seen. I have tried multiple throttle pumps to no avail, still a slight miss off idle. If I clean the piston bore and piston then lube with a bit of seafoam the hesitation goes away for a few hundred clicks. may point to a worn piston bore?..could the bore be sleeved? . I found a loose accel pump works better than a tight pump. im pulling 22 pounds at idle but I do have a bit of play in the throttle shaft..... culprit ? I also noticed that some springs in some kits are a little heavier than the ones pulled from the carbs?

I can almost see a m211 Rochester finding its way under my hood.

[jim lee]

I had a setup with an early weight (lighter) and a well worn leather piston. No hesitation at all. But the leather finally wore out and I've not been able to get it to work right since.

-jim lee