The Stovebolt Site Forums The Shop Area Engine Shop Dead horse kicking- Rochester B accel pump

Hi Folks-
Fiddling with the carb on the '52. managed to cure about 1/2 of the off-idle stumble by (more) cleaning and probing with a dental pick until I found the discharge hole for the pump shot. Worse than finding the idle passage on an Amal! I'm no novice to carbs, a year ago I was fighting a pair of Solex PHH44's (Look 'em up- Horror Show!), but I am learning the B models. Question is- on the early B carb does the accel. pump well refill by suction passing fuel into the well past the pump leather? There is no fill port/ check ball like on the BC's and no slot like on the later 2bbls. My carb is working OK but this has me scratching my head.
Thanks in advance for any shared knowledge.
Mike Burgess
Albert, KS

Its never looked right to me either. It looks like when the bowl is full the fuel runs through the center of the pump plunger with a check ball in it.

So true- I looked and looked, poked and probed, even got out my big cheaters and a bright light. Couldn't see any other way that the pump well would fill. I'll look more closely at the pump plunger. At this point the air horn might as well be on with Velcro anyway.
Thanks
Mike

This explains it very nicely
http://chevy.oldcarmanualproject.com/shop/1949_53/06engine/6_074.HTM

Hi Ed-
Thanks for the lead. In the "52-53" section I found a diagram of my carb! The picture you referred to is the same as in my "Fix your Chevrolet" book from '62 and the '69 Chilton's.
Here's my carb- http://chevy.oldcarmanualproject.com/shop/1949_53/06engine/6_081.HTM
Totally different and simplified pump feed system. The outlet for the fuel is also in a different spot. Couldn't have found it without you!
Cheers-
Mike

Even in the 1950's there was concern about fuel volatility (so much worse today).

The hole in the center of the pump, and the check ball are to release air bubbles formed in the pump well by percolation. Without the hole, pressure would gradually build in the pump well, slowing pushing the fuel out of the pump well by way of the pump discharge, leaving only air in the pump well.

Obviously, this condition would mean the accelerator pump would not function on the first couple of pumps until the pump well refilled.

Jon.

Hi Folks-
Thanks for the replies. Had a good thrash Sunday. Air horn off again, more crud surfaced, tweaked the float setting and off she went! I believe the pump leather is getting saturated and doing better. After a point set and plug clean I drove the old truck 5 miles! Nothing fell off and I got back home! Victory! On to some different system checks and adjustments/repairs......
Best-
Mike Burgess
Albert, KS