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Discussion Starter · #1 ·
OK - cheating a little here - I've got a 59 BelAir, but from what I see on this site, I'm in the right place to get my problem solved!

2 years ago she started flooding-out when hot. Took the carb (Rochester BC) to to the best carb rebuilder in Grand Rapids, who said it was full of rust, but after he was done with it, it was guaranteed to purr. Prior to reinstalling it, I installed a new gas tank, fuel lines, added an in-line fuel line filter, and made sure the rebuilt carb had a new internal filter at the fuel inlet. Filled the tank with fresh gas.

From the first time I started her after all the above, I have to use several squirts of starter fluid to get the engine going - once it's warm it'll idle on its own. Mixture screw is almost all the way out in order to keep it running. When I give it gas, it stumbles/hesitates, and runs rough. When I cup my hand over the carb throat to choke-off some of the air, the RPMs come up and she purrs like a kitten. But when I get her on the road, she stumbles every time I hit the gas, and there's just no power to climb any sort of hill, much less accelerate from a green light without people behind me blowing their horns.

Took the carb back. He went over it again, and again declared it good.

Since then, I've ruled out vacuum leaks, and ruled out a constricted exhaust system (ran the engine with no muffler & tailpipe - made no difference). Rebuilt the heat-riser valve - working perfect. New intake and exhaust manifold gaskets - no leaks there. New fuel pump, spark plugs, gaskets under the carb and under the carb's spacer at the manifold. Today I checked the float adjustments - both were off a tad so I corrected them, but still no help. Also ran it today with fresh gas from a 1-gallon can in the engine compartment feeding the fuel pump. Nothing's worked.

I'm out of ideas. Any takers?
 

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Afew things to check on this problem would be a faulty ign.coil,
plug wires bad
ign. points burned,pitted,sticking or bouncing
weak spark
leaky eng valve
choke set too rich
throttle linkage not properly adjusted
small debris in carb idle passage,jets
eng compression low
preignition,ign. timing off.
Some times an obivious thing can throw you off.Its happened to me before.Hope this helps.:anim_25:
Big Bob:flag4::bowtieb:
 

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Has it ever ran correctly ? I agree start with the basics . Which sounds like you are.The stumble sounds like acellerator pump do these single barrell carbs have one? Have you done a compression check ? Like I have mentioned before one this web site its tough to diagnose without being there. Have you done a plug reading ? Is the vacuum advance working,are the points fried,what's your timing set at. Just a few things to check hope this helps. There are only a few circuits in a carb did he dip it and blow all the passages out. Don't know what else to mention.
 

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If you choke it with your hand as mentioned you have proven that it is to lean.I know you said you rulled out a vacume leak but it sure sounds like a **** of a leak.If the car has power breaks try blocking of the power break vacume hose.Useing spray can type of carb cleaner spray staring at the carb base and work down.If it has power glyde or turbo type trans the vacume hose on the trans could be the problem or the modulator valve on the trans could be leaking being that they are vacume operated
 

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Discussion Starter · #5 ·
Greg, this car's been in the family since the mid-60s. It's got 65K original miles on it and ran great until a couple summers ago when it kept flooding-out when idling in hot weather. That's when I took the carb to get rebuilt, and they found it full of rust from the gas tank. That's where I started my original post today - with the new tank, lines, etc, etc. etc. Once everything was cleaned up / replaced and the rebuilt carb was installed, instead of flooding, it's now (seemingly) starving for fuel. I can't get past the fact that the only thing of significance that changed between then and now was the carb got rebuilt. Before the rebuild, the engine had all sorts of power, and after the rebuild, it was where it's at today - seemingly starving for fuel. To your other questions: The carb does have an accel pump. Compression check says no issues there. The vacuum advance appears to be working (physically, anyway - I can see it working when I give the carb some gas). A garage I took the car to a couple weeks ago said the points look good, and the timing was spot-on. The carb guy's got it again today - with the description of the problem I've given him now, he's going to zero-in on the the pump, jet, etc. We'll see...

Iequipu, no power brakes in this vehicle, and it's got a standard tranny. Only one vacuum line in this car - from the carb to the vacuum advance unit. Will double-check for leaks when I get the carb back again. I did do the carb cleaner spray thing and found several leaks around the manifolds - hence new manifold gaskets which eliminated those leaks. No leaks found around the base of the carb.

Big Bob - thanks for this things to check. You're the second one in a couple days to mention a weak coil. Thanks for all the ideas - will work on them if I've still got issues after that carb gets back in a couple days.
 

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I think what you really should do is find yourself another carb core or even better, a carb off a running motor. It sounds like there is crap or some other crud in some of the passages idle, off idle, and if you look, the only way to really access some of these area is to pry out the little lead or aluminum plugs and clean it out. More work than it is worth. Those rochesters are just not that rare. Btw, eBay has had a couple of nos carbs recently. Not cheap, but not that far off from the cost of rebuilding.
 

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Discussion Starter · #8 ·
I think what you really should do is find yourself another carb core or even better, a carb off a running motor. It sounds like there is crap or some other crud in some of the passages idle, off idle, and if you look, the only way to really access some of these area is to pry out the little lead or aluminum plugs and clean it out. More work than it is worth. Those rochesters are just not that rare. Btw, eBay has had a couple of nos carbs recently. Not cheap, but not that far off from the cost of rebuilding.
That's what the rebuild-guy said - if the third time isn't the charm, he's going to look for a new carb for me. Thanks for your reply!
 

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:anim_25: with all this as I would be pulling my hair out after all the effort you have gone to to eleviate this problem. I would go with the suggestion of trying to borrow a carby that is running and see if that makes a difference. Just to rule that out.:anim_25::congrats:
 

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Discussion Starter · #10 ·
:)

Success at last! The carb rebuilder took it apart again and found that the ball that's part of the power valve assembly was stuck in such a way that it wasn't letting fuel get past it. He freed it up and played with it a while, and didn't take long for it to get stuck again. This particular ball was part of the rebuild kit he used, so he dug around in his junk carburetor pile, found an old BC carb and compared the two balls - their diameters were a couple thousandths difference. So he put the ball from the junk Rochester carb into mine and it never hung-up like the new one did.

I put the carb back in the car and fired it up - runs like a charm again. No problems during a subsequent 25 mile Sunday afternoon in the country - looks like everything's back to normal.

Thanks for the feedback and encouragement to stick this one out, guys!
 
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