Hi guy's... I have 3 rochester carbs on a sbc in my '33 pick-up. The outboard's are real "dead" bases off a '66 goat(large bore). I rebuilt the center a while ago and it run's great. I never got around to getting the other's done because i was driving it so much. Well, i just rebuilt them too. My problem is when the outboard's open(either one/or both at the same time), the truck olmost dies. It start's to shake like a vacuume leak. They are getting fuel, and i set the float level's to factory specs.New acc pump etc... The bases are sealed real good too (it will run with just the bases on the intake without the carb body attacthed). I even did the spray the bases with carb cleaner trick..nothing! I've done a bunch of carb's..and messed with as many2 and 3 carb setup's before, so it's not like this is my first time at these, however, This one right now has me stumped!! Any of you run into this? And if ya did..what the hell's up with this thing?? Thanks, Rat..
Pull the carbs off,,,dump the water out of them,,,put the hood on it when driving it in the rain & snow....problem solved!
Ya know,,,, ya might have a point! I was thinking of fitting that hood we made for the "winter" rather than using that garbage bag. Rat...
the outboard carbs may be too big. of course you got 'em coming in at about 3/4 throttle? with all three reaching WOT at the same time? you using vacuum advance? got Enough fuel? all accelerator pumps working? Paul
Acc pumps work great. fuel pressure is about 5lbs no vac advance. they do come in at about 3/4 and reach wide open at the same time. I would have thought they were too big ..but, when i mash it, it's not stumbling on fuel..no black smoke at all, and as soon as i let off, it's fine. you don't have to clear it out like it's too rich. Thanks for the idea's...it all helps. Rat..
First off, I can't believe we're doing this over HAMB....instead of your freek'n garage like we're supposed to be doing. Wings and beers CAN be consumed in your garage yo know.......while working on the truck or car or whatever???? Billies does take out. The 305 errr 283 or whatever that poor little thing is you got in that truck is a wheezer and probably doesn't have the oats to take all three carbs. Remember....these were designed to be on a motor 25 percent larger than you've got...and the motor you got is tired to boot. Thats probably most of the problem. Start by making sure each of the outboard carbs is putting out a good (no, real good) accelerator pump shot. Some of the early poncho set ups were vacuum actuated. The outboard carbs on those came on pretty gradually when in original tune. The pump shot on the outboard carbs may not be early and/or strong enough to deliver enough fuel to a whole bunch of air when used with a mechanical linkage. Will the motor eventually take them when opened up gradually?....or does it just fall on its face regardless of how the outboard carbs are opened? Have you tried pulling the linkage off the carbs and reving the motor on each carb indiviually to see of one or the other has a fuel delivery problem? I'd start by backing off the outboard carbs. Adjust them for 3/4 throttle when the center is at WOT and see what happens. If you get an improvement keep pulling back or adding throttle to the outboards to see what the motor really wants. You can also play games with the linkage to bring the outboard carb opening on earlier but much more gradually. Here's a question....did the motor ever take just the center carb clean and hard without falling over or any stumble? If not, there are other problems to address. Geez. Use the damn phone next time, would ya? -BigChief
Big Chief... !!! No really though, The early poncho's were vacuume, first year for mechanical was '66, which these are. I can manually squirt the accel pump and get a real good shot out of 'em. Although, that dosn't technically mean it's enough. Now, i have disconnected the front from the rear and both from the center carb. The center carb has very good throttle response, considering most all of them seemed to have a flat spot on hard accel. When opening either front or rear carb, it has the shake and really bad stumble, olmost stall. Dosn't matter how fast or slow they open. I even opened the center and front by hand, then the rear and center, and it did it. I know that this motors a little tired , but i even adjusted the outboards to open lees than they should trying to compensate for maybe too much all at once.. No deal, same thing. Now, why ask on the HAMB rather than the phone you ask... Because i know your gonna look at it along with MANY other's that may have had the same problem.. so i get your input along with the rest.. Purty smart tinkin eh? Oh yeah, thanks!! Rat.. PS...when we goin to Billy's man????????i'm needin wing's and beer!
you know, I know a guy who is having pretty much the same problem. Run fine on the center carb, but*****ty when they all open. Like a big hole in the power curve. Somebody said that only the ceter carb is supposed to have an accel.pump, and the outside carbs are supposed to have it disconnected...but I am not so sure this guy know what hes talking about... oh yeah they're rochesters too...Hmm. Good luck. -J.
Tony, I had a three deuce set up on the C-Dan. The center carb was the only one with an accelerator pump in it. There was a slight lag when I put all three into service, and I could never open em all up right off the line. Had to roll into em. But anyway, mine was built by Charlie Price at Vintage Speed. Maybe HE can answer your questions? I'm about as useful as a rubber crutch. Also, my end carbs had no air fuel mixture screws. Do yours? Could they be set wrong? Spike
I have a factory Eldorado 3 X 2 with Rochesters and all three have accelerator pumps. I am not sure what jets are in the outers, I can look if it will help. I have also heard the GTO carbs are HUGE, are you sure it's not supplying too much fuel. I'm having the opposite problem, still trying to get the center carb tuned, my outside ones work fine. Not to Hijack but what's that about vaccuum Vs mechanical linkage and fuel delivery when you stab it, I don't follow. TZ
seems to me that if the center is good and it stumbles on the outers, then whatever fuel to air mix on the middle is correct and incorrect on the outers, to little or to much i dont know. are you running electric fuel pump or mechanical?
Mechanical GM pump with a reg set at 5Lbs. I've set up a couple other rochester tri-power set up's, all had acc pump's on them and worked great. I know these carb's are big, but believe it or not, i don't think it's gettin enough fuel. I think i'm gonna pull them back off again and check all the passages a little better. Spike, mine are true tri-power bases without adjustment screw's. Thanks for all the help guy's!! Rat....
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