Holley 94 on 8ba barely runs

JRN1967

JRN1967

Senior Member
I've got an 8ba with stock dist. and a single Holley 94. The distributor has new points, cap, condenser, 12v coil, new resistor wired in series. New plugs and wires. Copper vacuum line is tight from carb to dist.

Holley 94 has a new kit from Daytona Parts, installed by me. The power valve is a 5.5 and is supposed to be the one that has the flat surface so it doesn't leak. Float is set to 1-3/8". Jets are #51. Throttle shaft isn't loose. New base gasket.

New gas, new tank, & new gas lines.

Timing is set with a light to the bump on the crank pulley. But the pulley is from the wide belt truck and the cover is from a 1950 car. Not sure if this cover pointer is right for the truck style pulley?

This is in my 31 coupe project.

When I try to start the engine it catches right away. If I feather the throttle I can keep it running, and if I do that for a while I can keep it running barely on its own with the idle screw maxed out, but the rpms's are very low. Seems like all the cylinders are firing. But it hesitates if I goose it.

If I turn my idle air screws in it will stall, which tells me its not a vacuum leak issue.

Any idea why I need to have the idle screw maxed just to keep it running?
 
Remove your spark plugs and look at how there burning then that’s a good time to take a compression test start there let us know what you find
 
Is your choke operating properly. Fast idle with choke closed? The idle screw rests on that choke arm. I had to turn mine in farther than expected, but not all the way.
 
Have you tried turning the distributor a bit either way when it is running? It might be better to tune by ear rather than relying on marks etc.

When you rebuilt the carb did you check the surfaces of the body and base were flat?

Other than that I don't know what to suggest. My experiences normally revolve around the carbs running rich rather than lean.

Why a 5.5 power valve? Stock is 7 or 7.5 (not sure).

Mart.
 
If it's that lean then something is likely plugged up inside and not allowing flow to happen. CharlieNY has a fix for leaky power valves but I don't think that would make for a lean mixture at all.
 
Mart has the answer the 94 is the wrong carb for an 8ba distributor. Can't run thestock dist. on intake vacuum.
Gramps
 
You said you have a 12 v coil with a new resister and the resister is wired in series. lets make it simple the resister is only in line when the engine is running it is not wired in the start circuit. The engine is only started on 12 v. The wire from your Ignition switch sta. side goes to the sta. side of the solenoid, the wire from Ign. side of the solenoid goes to the resister. As OL' RON said you need a 94 with the vacuum on the carb. not manifold vacuum.
 
Is it a 1.5 Ohm primary coil or a 3 Ohm primary? One needs a ballast on 12-volts and the other doesn't. Parts for old points ignition systems don't always specify what voltage or ballast recommendations should be used. Most manufacturers don't know the difference any more since stuff is either made south of the border or offshore.

The 8BA carb is basically a 94 modified to work with the Load-O-Matic ignition system. The pre-8BA carbs were set up to run a vacuum brake on a front mounted distributor. The load-O-matic is a different critter.
 
Appreciate all the answers. I believe this carb is a 94 for an 8ba with the vacuum on the back of the carb to the dist. Not directly from the intake.

roto - I'm not sure of if the coil is a 1.5 Ohm primary coil or a 3 Ohm primary? I will test tonight.

Mart - As you suggest, I will bump the distributor while its running and see if anything improves.

Frank - I questioned the new condenser as well, but I'm not sure how to test it?

The fuel pump is the only part that hasn't been replaced, I don't have a gauge on it to check pressure, but there is fuel when I goose it.

Thanks for the help,
 
Sometimes you have to go through multiple new condensers to find a good one. "Squirrel" on the H.A.M.B. dissected some new condensers that were "bad out of the box". He found the the pigtail was not connected to the internals of the condenser, but just laying on top of them. They were relying on the crimp holding the end cap on the condenser to apply enough pressure to make the contact. Sometimes, that's just not enough.

Most multi-meters do not have a condenser test position, but some expensive ones do. If you test one make sure that you test it both cold and hot because heat can effect them.
 
tubman said:
Sometimes you have to go through multiple new condensers to find a good one. "Squirrel" on the H.A.M.B. dissected some new condensers that were "bad out of the box". He found the the pigtail was not connected to the internals of the condenser, but just laying on top of them. They were relying on the crimp holding the end cap on the condenser to apply enough pressure to make the contact. Sometimes, that's just not enough.

Most multi-meters do not have a condenser test position, but some expensive ones do. If you test one make sure that you test it both cold and hot because heat can effect them.
Click to expand...

I've got a Fluke 87... I'll research and see if I can find a way to test it. Thx
 
A person needs a dedicated capacitor tester to fully test one. A person can test with a digital oscilloscope set up while running but would have to have a set up that works with a lap top to get that function.

The 8BA carbs usually have the "8BA" casting marks on the body. They use venturi vacuum to function the spark advance/retard control. There is no centrifugal advance on this system. It's all vacuum operated. It's a good idea to test the vacuum can too.

As someone mentioned, the idle fuel circuit is likely blocked or there is a hell of a vacuum leak somewhere.
 
I was having a similar issue but not as bad. I found the issue by installing a glass fuel filter. I replaced the fuel pump pedestal gasket because it was leaking. After that the problem got worse to the point I was like four turns out on my idle mix screws. On accel it would hesitate and sputter. I was chasing ignition issues as well and that made me chase my tail a little bit.
After replacing the fuel pump pedestal gasket and the problem got worse, that pointed me to a fuel issue. The pump was new so that was not suspect. I installed a glass inline filter and found lots of air would run through it. So I went through the entire fuel system. I had symptoms like "Vapor Lock."
I installed an Airtex inline pump and regulator and it runs really great now. Purrs down the road at 50mph.
7.5 power valve, 51 mains, 1.5-1.2 turns out on air/fuel screws, 1.5psi.fuel, 95-100psi on all 8, 18-19" of vac at idle. Timing is set to about 4-6* advance (eyeballing the dot/pin about 3/8" past dot on pulley.) Oil pressure is 30psi at idle @ 160*.

The problem sounds like fuel pressure. Pushrod wear and thicker base gasket magnified the issue I was seeing.

https://youtu.be/JZYAr9l4Ym0

https://youtu.be/xkmcvxsPdpQ
 
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