I'm still working through gremlins on my 3x2 that I just put on the '27. It now seems that i either have bad accelerator pumps or after a little bit of research perhaps the wrong size. My center carb is only squirting on one jet, and my front carb doesn't seem to be squirting at all - or not well at least. This would explain the flat-spots i get throughout the range of rpm's since I put the carbs on. With a bit of research, i found that there are at least 3 different accelerator pump sizes. How do I know which is the correct one? I can't just measure out the one that came out of it originally, because they were pieced together, and no telling if i even had the right one in there to begin with. Any help? Sorry if its a dumb question.
I would say the accelerator pump jets need a good cleaning. You may have to use a small drill bit to break up blockage in the jet p***ages.
If you have the accel pumps with the black rubber then they are junk. The older pumps dont get along with ethynol. Get hold of Carbking on here and he will fix you up no matter what you need. Here's a link to his website. http://www.thecarburetorshop.com/
http://www.carburetor-parts.com/category_s/284.htm Heres pics of your 3 different ones - about mid page. I can't tell you which ones you need but somebody else might. I do know the seals go funky after a year or two and need to be changed. I believe they all should work at least a little, maybe not the right volume of squirt but should give you some fuel. Which ones do you have ?
Get the good ones? Black are junk Blue ones I could be wrong but think the question is : it the 2.386 the 2.506 or the 2.640 pump he needs to put the good seals on. Since his carbs were pieced together he's got no idea which pump should be in there.
I just had the same issue Both my front and rear carb pumps Had ripped aprons on the the pumps I must have not aligned them Properly when ***embling them Was able to purchase 2 new one for a buck each Locally East fix ,,,,,my screw up !!
This is the correct question. Thanks Vicky. Fantm - wish i could find that deal. I'm looking at $10 each. But its the ****py ones that everybody says to stay away from.
You are running accelerator pumps on all three carbs? This doesn't answer your questions, but if you are running progressive linkage I would think that you could block off the pump circuit on the front and rear carbs and just run one on the middle carb.
Yes, running progressive and have accelerator pumps in all 3. Is that bad? Should I not do that? \\\insert George Castanza JPG here\\\
No its not bad , you need an accelerator pump for each carb. What you don't want is idle circuits on the end carbs
I wouldn't run three accelerator pumps with progressive linkage if it is truely set up progressive. You idle and start off on the center carb. That one should have the accelerator pump. Some would say that you increase the size of the pump until you get rid of the bog. In this case I would start with the largest one since with three carbs you will most likely need it.
You can split the top/bottom on those Rochesters and silver solder the idle circuits shut (front and rear carbs only).
Every multi carb set up ever designed by Rochester has had an accelerator pump in every carb. I'm calling BS on you being able to get a triple 2bbl Rochester set up to run with out the end accelerator pumps. Not gonna happen. And its not helping Jmel figure out what he needs. Start another thread and back that nonsense up. Its tech week get busy.
As others have stated, FACTORY tripowers using Rochester 2 barrel carbs came with accelerator pumps on all three. Since the outboard carbs on these setups were basically "dumpers", the idle circuits, chokes, and power valves were eliminated. As far as what accelerator pump to put in "patched together" carbs I have no clue. In addition to different diameters, Rochester used different length pumps to control the volume of the pump shot; and some carburetors have the intermediate pump shaft a different height above the floor of the bowl. There are dozens of physically different pumps! As far as simply inserting the proper diameter cup on the pump you have...this may not work satisfactorily. The retaining thimbles on the bottom of the pump are different diameter. Installing a small cup on a large thimble will cause the thimble to stick in the pump well. Installing a large cup on a small thimble will cause the cup to flip, and stick in the pump well. As far as colors of pumps. We have tested every rubber (neopreme, natural rubber, fluro-elastimer, etc., etc., etc.) that is available. Of these, we have had the most success with the very dark blue skirts using a garter spring. However, we have had these fail as well. The only material we have found that is totally reliable with modern fuel is leather. Jon.
Thanks for your response Jon. I was actually about to IM you before i saw your message. It apepars that the diameters are all the same on these, however its the lengths that I'm not so sure about. Sounds like I'll have to work through that problem. Do you have any leather skirts or know where i can find them? We used the skirts that came with the rebuild kit, but they were garbage, one was torn out of the box and had to pilpher one from another carb.
There you go ^^^ I did find some more . Apparently there are two different size bores 21/32 and 3/4 " that should only take a little bit to measure yours and find out what you have. There's at least 3 different lengths at 3/4 and 4 at 21/32. I'd choose the middle most ones and hope for the best. You may have to go up or down depending on how it runs. For reference http://quadrajetparts.com/rochester....html?osCsid=0de3549544456c7386be743c622bee82 But I'd get the parts from carbking
Well, I did it again! I just typed a nice long response, clicked the post ****on, and got the infamous "you do not have permission to post" response. (Timed out). Not going to type it again. I know, I should have done a copy, because of this forum; but I didn't. A quotation from my GTO license plate is in order (GRRRR!) Short answer - leather skirts REQUIRE special thimbles and springs. Jon.
Hi Jon, Thanks for your input. I sent an email. Thanks again to everybody else who helped in this thread as well. I shoulda left well enough alone with my Edelbrock 600...but I've been wanting a 3x2 since I built my car. Thrilled to death with the looks, not so much with the performance so far. Hope to have it figured out soon. Learning a lot here. Can't thank ya'll enough.
It's my favorite carb setup, 3x2 rochester small base. I got my first one almost 45 years ago, and all I have had, ran sweet. But they are always real tripower carbs, not converted primary carbs. Jon will get you on track
Setting things straight: 31Vicky is dead-on right about the accelerator pumps. I was thinking about power valves base on past experience on multi-carb setups and had that on my mind when I jumped in too fast with my comments (sorry if I confused you Jmel). I was a little embarrased when realized it but I'm glad I have thick skin. Getting old I guess.....
I'm not worried about it 42. I was curious how the fuel would be pushed from the bowl without the accelerator pump...but I'm also quite new to this. For the record, both idle circuits and power valves are blocked off on the outside carbs. Wish i could find these pumps or leather skirts locally. The Invasion in Dallas is this upcoming weekend and would like the '27 to be running right by then. Oh well....its still drivable and will still make the show regardless.
JMel, When tuning, keep in mind that the accelerator pumps only give you a SHOT of fuel when you open the throttle plates. From there its all about fuel dumping through the main jets. Enjoy the show. 42coupe
Emails are answered, time permitting, on Saturday afternoon. If you are looking for more timely information, 573-392-7378 (9-4 Mon-Wed central time). Jon.
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