Frustrated

F

Fat Fender

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Here's the big picture. I've rebuilt a 59a engine (new bore, pistons, valve job, mild cam). Installed 4" crank with all new bottom end. Had the rotating assembly balanced. I want to run dual 94's, dual exhaust. I have an electric fuel pump with regulator. Reads 2 to 3 lbs with engine running. I installed one carb on the manifold and sealed off the second one. Started the engine up with butterflies mostly closed. Started OK and idled OK but not great. I have an oxygen sensor and meter to view the air/fuel mix. With the choke mostly closed, the air/fuel ratio is right around 15 to 1. Odd since one would think that with the butterflies closed, it should have read richer. When I opened the butterflies some, the meter read 22 to 1 and greater. When opened all the way, the engine would not run. Swapped carbs, same result. Tried a 3rd carb, same result. Tested compression. All cylinders around 95 psi plus or minus 2 or 3 psi. Thought I might have an air leak. Changed intake manifold gasket, no change. There is only one fitting on the manifold for vacuum fitting. Sealed it off, no change. My stock dizzy is set to full advance. Anything less and the engine idles worse. I am at altitude (6200 ft) so I initally installed smaller main jets (47's). I re-installed 51's, and no change. I played with th idle adjustments. Screwed them all the way in and all the way out, no change either way. I'm all out of ideas and am totally frustrated. Any suggestions would be greatly appreciated (I getting to the point that an SBC might be a good suggestion....). I've always received great ideas from the Fordbarn crew in the past and am among the novices that greatly appreciate the time and responses from the more experienced.
Thanks for any help.

Fat Fender
 
It may sound stupid but the adjusting screw not making any difference sounds suspicious, wonder if a gasket under the carb may be blocking a port on the carb hmmmmmm just a thought, good luck.
 
I'm running a similar set up in my pickup with the exception of a Mallory breakerless ignition. Its running pretty good.

What is the condition of these carbs? Were any run on another engine? Does it run if you fill the carb bowls before you try to start it. Are you getting decent flow through the fuel line - 1 pint in 10 to 15 seconds.
Things to check:
Float level: 1 5/16" to 1 3/8" is recommended.

Flow through the jets: Remove the carb top. Shoot aerosol carb cleaner though each jet and observe flow in the venturies.

Accelerator pump flow. Look for spray from the nozzles when the throttle is opened.

Point gap .014 on both sets. Try a different condenser.

Plug gap .025 to .030.

Ignition timing

Cam to crank timing.

Remember; NO SBCs!!
 
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you say you have a duel carb manfold & you blocked off one carb. the eng will not run right this way. the manfold is designed for two carbs. on a three set up you can block off the front & rear & run on the center. put a single carb manfold on & see how it runs.
 
Richard has a point. Depending on the manifold configuration the engine will not run well on one carb. If you are running an Offy regular dual, as shown in my avitar, it has a plenum connecting both carbs. In that case one carb can be blocked off successfully. I ran the NE tour on one carb. If you are trying to run a super dual the engine may be on only 4 cylinders with one carb active.
 
richard crow said:
you say you have a duel carb manfold & you blocked off one carb. the eng will not run right this way. the manfold is designed for two carbs. on a three set up you can block off the front & rear & run on the center. put a single carb manfold on & see how it runs.
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Your onto something there Richard,the runners are not right to do that. ken ct.
 
Were the carbs rebuilt? Do you have the correct power valves? I don't mean size, I mean the shape of the shoulder gasket surface. Newer PVs on old carbs are known to leak and it sounds like your dumping fuel.
 
My 49 Ford pickup with SBC 327 would not run correctly.Traded carbs that ran well on other engines,no change.Traded ignitions,same thing-no change.Swapped intake manifolds,WALLA! The old manifold had an internal crack(visivle with manifold off engine).Could your intake manifold be the key to the problem?I was looking for a cliff to run it off as I'm sure you are considering now.Hope this helps! James:)
 
With 2 94s you also have to have the low open (inches Hg) power valves. You will probably need 4.5" Hg or maybe even 3.5 " Hg for the altitude you're at. All depends on the cam and altitude. Someone who knows the 94s real well could steer you better.

Kerby
 
Put a stock intake manifold on it and tune each carb individualy then reinstall the dual manifold with both carbs.

Jim
 
I think you are playing with your new tools.I have never hear of these test.Put both carbs on and get out and test drive it.Get both carbs to open even and operate both at same time.
 
I ran duals on my pickup years ago on the original '47 flatmotor and had to change the power valves to a lower number to get it to run. They were 94s.

The intake manifold was one made here in Australia and it wouldn't run on one carb either. Both carbs need to be set up and tuned on the dual manifold.
Chris Tassie Devil
 
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