So this is the 4th carburetor in a row that we've had this problem with. The accelerator pump not functioning properly. In this case, the piston just doesn't want to travel in the bore. It seems that the diameter of the rubber cup is just too big and it's jamming in the bore. I've purchased multiple kits and they all have the same parts, (blue cup with a spring inside) and I can barely get the cup down into the bore without an unusual amount of force. Once its in there, it feels like its jamming. We had another 2GC recently that was on a car that the guy had freshly rebuilt at a big carburetor house out here. It had the same problem and it had the same parts that are in the kits. Any idea maybe where to find a different style accelerator pump or is there something we're missing? Thanks in advance for your input.
There’s two different sizes; 21/32” and 3/4” make sure that you are using the correct size pump cup. Some kits came with both size cups, some don’t. Sometimes there’s corrosion in the bore that causes them to stick, it doesn’t take much.
Thanks. This set up is 21/32 and the bore is clean as a whistle. Same with the last one we had this problem with.
Had the same problem. Turns out the pump supplied in the kit is not the proper pump. I believe this pump you need has a leather cup. I got a couple from a carb rebuilder. If you want more info call me at 705 934 4434 or email me at wfrickard@gmail.com
Thanks. I haven't been able to find a leather pump around here. Every carb shop I talk to uses the kits with the rubber pumps. If I can't find one, I'll hit you up.
Yep--go get some crocus cloth, do NOT use sandpaper of any grit. Go in circles, not up/down and make sure to travel the full length of the bore. If its a new rebuild, use some lithium grease in the bore for the cup to slide on for the initial startup. Like others said, be sure you have the right pump.
I talked to him. He said he couldn't help without the carb tag number, which of course i don't have and I can't find my dial bore gauges to measure the pump bore.
The reason carbking wants carb tag numbers (or the stamped number on 1968 and newer carbs) is these accelerator pumps have variables: (1) pump cup diameter (discussed in this thread) (2) overall length (3) compressed length (4) type of end on pump shaft Between the 2G series and the 4G series there are at least 50 different accelerator pumps. As far as suggestions go: I know this won't be a popular answer, but make the pump! That is why we have leather pumps, is because I make them. Jon
If Jon can confirm that there were only two bore sizes, you could use a piece of .750” round stock to verify if it is the 3/4 version or the 21/32 (.656”) by default. Then check eBay. Search “2GC leather acceleration pump”. I found several offered.
There are only the two that one is likely to encounter; as mentioned 21/32 and 3/4. Just for grins, I grabbed a 50 year old catalogue, and 43 different pumps were listed for the 2G series alone. Jon
The ebay search found 3 for the 2GC and 2 of those are not leather! Looks like my prices need to increase! I have only been charging an extra $15 for the leather pump kits over the kits with the modern chemical pumps that I cannot pronounce or spell. Jon
For those who might buy one of these, and have never before used a leather pump, one should place half a dozen drops of light machine oil (neetsfoot, 3 n 1, sewing machine oil) on the leather a few minutes prior to ***embly. Jon
Neetsfoot oil works like magic on the leather plungers. I’ve had some that were mighty old and dry but they came back to life after a soak in that stuff. My Dad introduced me to it back when I was playing in Little League baseball, to keep my gloves pliable. Been using it ever since.
I recently had a 2G with a pump not working, I used some 600 grit paper just enough to remove the high spots, then red scotchbrite wrapped around a wooden dowel rod that I polished the bore with. It worked great, the pump ran smooth with no more binding.
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