Rochester rebuild kit issues

Since I rebuilt the carb on this newly acquired '67, it's had a serious stumble off-idle. It was definitely an accelerator pump issue; today was the first chance I had to look into it.

Aside from the internal pump linkage arm binding from being in backwards, the new rubber plunger is either too big or has swelled and gotten floppy. It is binding in the downward travel (not a smooth easy motion), and it dislodges itself off of its seat on its up travel and gets tangled up in the return spring, rendering itself useless.

To explain the downward binding, I would almost assume the check ball is getting stuck, but I mic'ed the old vs. the new before I swapped them and they were identical size.

It just feels like there is way too much friction. I smeared some Vaseline in the bore and it worked fine until the fuel entered the carb and washed it away.

I'm not sure of the brand of the rebuild kit. The box (and the old plunger) is a few (thousand) miles away. The pump plunger material is blue. Another victim of ethanol? Am I overlooking something? Or did they stick the wrong plunger in there?

I've got my dad dumpster diving for the old plunger... I'd hate to buy a whole second kit just for that one piece.

 

I gave up on my pile of 2 jets. got an offenhauser intake and a holley 4 barrel. solved my 2 jet issues perfectly.

In the kits that i have had, there are a couple different accel pumps. One fit right and the other didn't. Had the same issue as you. These guys here will give you better advice than me.

 

I hear you on the 2 jet troubles. Fussy's carb runs just like you describe. When cold, I have to have the choke on. Once it warms up, it's quite a bit better, but certainly not 100 percent. From 2 different rebuild kits, I had troubles with BOTH accelerator pumps popping apart and totally jamming up the internal linkage. Right now, I'm running with an old accelerator pump from a core carb I got from Pack Rat on this forum.

I think the problem is the low quality of the carb kits from the parts stores. I've built a few hundred carbs in my day (my specialty was Q-jets) and never had the troubles like current manufacture kits cause with this 2 jet!

 

I'm glad to hear it's not just me. If my dad can't find the old one (probably won't), I'll have to do a backwoods boonie fix on this one. Probably fab a washer or e-clip under it to prevent it from popping off.

Chinese crap.

 

I just found this page.

http://www.carburetor-parts.com/Rochester-2-Jet-Accelerator-Pumps_c_601.html

Apparently, there were two different bore sizes with only 3/32" difference. I'll have to see if I can fit my calipers down in the accelerator pump bore and see if mine is the 21/32" bore and I'll measure my cup - I'll bet the one in the kit was for the 3/4" version.

If not, its just junk from the get-go, which is entirely possible.

 

If the pump is from an old kit it could be susceptible to ethanol damage(?). Read more about on the Mikes carbuerator parts page you linked.

 

I saw that, and it could be... We'll see. My dad found the old one (measures 21/32") and is sending it out.

We have quite a few stations with ethanol-free gas around here. I'll make sure to only run that - for more reasons than just that cup. The extra price is worth it, IMO.

 

My old accelerator pump arrived in the mail yesterday. Here they are side by side. The white one was in the new kit, and the yellow one was the old one. Notice the old one's internal cup spring and wider foot to prevent it from moving. It is working MUCH better. They do both measure the same diameter, but the old one is just a better design.

 

If you need a new one check out this site, they have the same style as your old one.
http://quadrajetparts.com/rochester...2-garter-spring-style-length-1006a-p-659.html

 

Yes the old style with the spring had better bore sealing contact, but allegedly wore out faster - hence the new guaranteed you'll need another design!?!?

 

Plunger -- Napa Part #2-4036

 

Awesome guys. Thanks!