Need holley 94 help

J

johnzmu

Junior Member
I'm about to pull my hair out. and I don't have much left, so I hope I can solve this problem soon. This is going to be a long message, but I want to give as much info as possible. I rebuilt an 8BA to factory specs, ant put it in my 51 Mercury pick-up. The first carb I overhauled for it is a holley 94 8BA model. it idles good and responds like it should when you adjust the mixture screws. problem is, when you go to rev it up it stumbles and dies. if you leave the choke almost all the way closed, it will rev up fine and run good. I decided to fool around with this carb in my spare time, so I ordered a rebuild and figured I could bolt it on and carry on with life. WRONG. the new carb is a 8BA model as well, and to look at the thing, it belongs on a concours car at Pebble Beach. but my engine runs like a toilet! runs extremely rich, black smoke pours out of the pipes, and when you screw the mixture screws all the way in, it makes no difference. these carbs are not that complicated, what am I missing???:confused::confused::confused: At this point I have no idea what is in the new carb for a power valve or jet size. the first carb I overhauled has the factory jets and whatever power valve comes in a Hygrade Jiffy Kit. Could it be that the first carb is fine, and there is other issues with this engine?
 
With respect, I think your questions are premature. These carbs, in your own words, are not that complicated. There are three distinctly separate circuits in your carb. Learn them, and answers to your questions may become self evident.

For starters, your description of it's symptoms suggests that all three circuits are dysfunctional after your rebuild. To attempt to diagnose your carb by those symptoms to one who hasn't the basics would not be in your best interest. Again with respect, learn the functions of your carburetor, then please return with your questions.
 
I will agree on a problem with power valves. The first time I rebuilt one of these carbs, it did ran worse than before the rebuild. Turned out to be an ill-fitting power valve. The ones for the later 4-BBLs look the same, but don't fit right. Also, some that don't have seating problems are simply too high. Put the power valve in and set the carb body on the base without the gasket. I had one power valve that was so high the body wobbled on the base, even with no gasket.
 
I can't say anything for the rebuilt carb I just bought(the second one) but I know the power valve is correct in the carburator that i put together is correct and does not leak. We have two different carbs here, an two totally different problems. Hard to blame the same thing on both carbs, but then again what do I know, everyone has their Vise, and mine is carburators. I just can't get my head wrapped around the concept, that why I turned to you guys.
 
It does sound as though there are 2 different problems depending on which carb is attached. Your first carb description makes it sound like there is a problem with the high speed circuit fuel flow. This can be caused by anything from low float level to blocked passages to reversed nozzle bars to misaligned gaskets.

The over-rich carb can have a loose or malfunctioning power valve, or stuck or mal-adjusted float, defective needle valve and seat or loose needle valve seat, no jets or wrong jets and/or other things wrong.

I don't think I can tell you specifically where to begin. Of course, all the carb work in this world will not correct a defective condenser or retarded timing or improper point adjustments.
 
For now I'm going to concentrate on the one that I put together, and the problem with this carb is, idles beautifully, but you have to have the choke 7/8 closed to accelerate, otherwise it stumbles and dies. Alan said in a previous post that I should study the three circuits and then go at it, and I totally agree with him, but this thing needs to be done today(hopefully). And the first thing I do when I get to the shop, is go through the ignition system again
 
Just a thought, with the engine off, remove the airhorn and blip the throttle by hand. Watch to see if the accelerator discharge nozzle is providing a stream into both venturis. Did you remove the little check ball in the base of the accelerator pump well whilst cleaning the carburetor?
 
I'm not at the shop at the moment, but when I get there I will check the nozzles. And yes I did remove check ball from the bottom of the accelerator pump well, cleaned that all up, replaced it, and did the check to see if it was seating properly
 
Reason I ask about the nozzle is after cleaning and before chromating, I run a fine wire through them to make sure the passages aren't plugged. Then I blow through it to see if I feel air from each one on my lip.

After all my cleaning processes are done, I like to take a can of carb cleaner and blow through all passages to see that cleaner is coming out where it should.

Rather than lecturing to someone about how they should study the various circuits in a carburetor, I once cut apart a junk 94, then used three different colored Sharpies and outlined the circuits. The fellows at my EFV8 club thought it helpful.
 
When I look in the carb, fuel comes it of the nozzles when you step on it, but it comes out in a solid stream. Should it not be more of a mist?
 
John, If you want to save time and get your engine running soon, send your carb out to one of the pro's on Fordbarn who rebuild them. He can then tell you what was wrong with it and you'll know what to look for next time. The piece of mind will be worth it.
 
After 4 hours at the shop, here is what I came up with.
Just to recap, trying to get an 8Ba flatty to run right using 2 different model 8BA carbs

1st carb, I cleaned myself and put a kit in, idles smooth but backfires and stalls upon acceleration unless you set the choke 3/4 - 7/8 closed, then it acts perfect in every way.

2nd carb, ordered a rebuild from Ebay, carb looks spectacular, looks like whoever built it knew what they were doing. bolted this carb on, and the thing floods so bad, it'll hardly run.

When I went to the shop today, I decide to open up 2nd carb and look at the power valve as per a few of you guys' advise. Guess what? WRONG PV!! and whoever put it together used three gaskets between PV and carb body. I had a proper PV in my collection of goodies, so I put it in, and now, 2nd carb runs exactly the same as first carb, a small backfire, and stall upon acceleration. leads me to believe something else is wrong

Verified a stream of fuel out of nozzles.
Verified 2.5lbs fuel pressure
Verified timing
Verified vacuum advance system works
Verified points at .016

what else should I look at?
 
I've had vacuum leaks do that to me and I've had a kinked fuel line do that to me.
I've been doing this less than 3 years and I make all the mistakes so ... just saying.
Have you had a vacuum gauge on it?
 
What is the timing set to? On an 8RT the bump on the crank pulley is where it should be set with the vacuum line disconnected and plugged. Is it possible you have the firing order wrong? They will idle reasonably well with a couple of wires switched...
 
A small backfire and stumble on acceleration indicates a lean mixture. Could be the accelerator pump or a vacuum leak. Good luck.
 
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