Hot Rods Dual 94’s Trouble

Hello all,

Having issues setting up some dual 94’s on my 8BA.

I recently swapped my stock heads and intake to a polished Fenton 2X2 Intake and heads.

While gathering my new parts I found matching 94s but they both needed rebuilt. I rebuilt them both myself. Now, let me say, this is the very first set of carbs I have ever rebuilt, minus some carbs I rebuilt for old dirt bikes when I was a kid. Everything went very smooth for the rebuild.

However, I didn’t realize they didn’t have a vacuum port until after I rebuilt both and installed them. They’re the 91-99 carbs. At that time I was running the load o matic dizzy. Fired right up, but no advance. So I ordered a SBC distributor from Bubba’s for mechanical advance!

I installed Bubbas shiny new distributor recently and all has went well. Timing is perfect and it sounds amazing.

Here’s my problem.

After I installed the new dizzy and set timing, when I put it in gear, the RPMs drop a lot and won’t go. When I hit the pedal, it just dies. Way too much fuel. You can smell gas coming out of the headers. At idle, it seems to be running very well, no smoke and no smell of fuel.

I reduced the Jets from 50 to 48s and reduced the PVs down to 4.5’s.

After swapping these, it is still getting way too much gas. I’ve adjusted mixtures and can’t seem to make any difference.

Idle is great and revs up very strong.

What am I missing? I’m thinking it’s something very simple that I am just not seeing.

Any help would be greatly appreciated.

Thanks,
Patrick


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I would say that your missing a good Carb man to help you...

 

Some info here to add to your confusion in this old thread. https://www.jalopyjournal.com/forum/threads/rebuilding-holley-94-s.32467/
Reading though post 4 might be pretty productive though. I've got a pair of matched 94's for my 8 B-A so I'm going to follow along on this pretty close. I have an Offy intake for it though.

 

How much fuel pressure?

 

I think you must have an automatic trans in this? And you tuned it entirely in neutral rather than in gear? It has to be able to idle in gear, and also not to then go to wild RPM when you park it in neutral. Also lack of vac input can give a few problems getting moving at low speeds. Flathead, like SBC, wants advance moving up rapidly when it starts to go.
Using a Chevy distributor makes it easy to put vac back in, obviously manifold or ported, not the venturi vac used with the '49 distributor. Pure centrifugal does not meet all the needs of a motor. Smokey wrote a long rant on the problems of centrifugal only in race motors...

 

Yes, automatic, C4. I will try tuning in gear to see what that does. Didn’t think of that...


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I'll take a stab.
So did you look at the power valves that you took out and the new ones that you put in?
If the old ones were correct they will differ from the new ones.
Not all new power valves are created the same
The area of the PV that screws into the carb body is where you need to pay attention.
The new ones likely are radiused where the gasket sits. If it is the valve will not seat and seal properly.
You need get power valves that have been turned down flat to sit properly.
Charlie Price and others have the proper ones.
A good guide to start with is a PV that is half of the vacuum at idle.
There are other things to look at but this is where I'd start.

Good luck

 

the one on the left has the radius removed

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Awesome, I will check them out. Thanks so much for the reply. Had a feeling that may have changed something. I purchased them from Mikes Carburetors.


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Actually with the right gasket the PV on the right will work.
This style power valve will not work unless machined, note the step where the gasket seats.

 

X2 on checking the power valve seal. I used thick fibre washers for a better seal.

 

So I checked the PVs and they seam to be sealed good. There was no fuel underneath either of them. Is there still a chance they could need machined to sit in there better?


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I would block them off completely and see what that does. Plugs are sold for this and are cheap.

 

Went to Jegs this morning and picked up the plugs. Installed both... and guess who took their roadster for a drive? Thanks so much for the help! Just need to fine tune the carbs and I should be golden.


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Usually have to fatten up the main a little when you do this. 5 or 10 numbers.

 

Well, back to square one again. Blocked PVs and that seemed to do the trick and I can drive it, but I can only barely hit the pedal very slowly to get it up to speed. If I go any harder on giving it gas it just cuts completely out and Boggs hard.


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Plugging the PVs was just so you could see if it cured your flooding problem and it appears it did. The bogging problem is to be expected because when you open the carbs now you get a bunch of air without any fuel to make the air-fuel ratio correct. You seem to have found the problem which is either the PVs were leaking as has been suggested or they are too large. First confirm that they aren't leaking because that is likely the problem. Then purchase some smaller ones ( 4.5 was suggested) and see if that works. You could just put the PV back in only one of the carbs to see if that works. Better to have both working with smaller values for a long term solution.

 

Thanks for the reply. I had 4.5s in and they weren’t leaking just before I blocked them off. How can I be 100% sure they’re not leaking?


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Quick update. I was on YouTube last night watching a rebuild video from Vintage speed. Charlie price was about to insert the “accelerator check valve.”

And that’s when I realized... I never removed that. I tore the rear carb apart this morning and that check valve was jammed in there and wouldn’t come out. I spent some time removing it. Finally got it out and put a spare one I have in. Meanwhile I stripped a screw putting back together so need to make a run to grab a new one....


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It should run pretty good with the block offs in place. Yes, your accelerator pumps need to work and you will need to increase your main jet size to compensate for the power valve being gone. But I ran with blocked PVs a lot. Maybe not ideal. But worked fine for me.

 

FYIW, I just picked up my dual 94's from CharlieNY. I am running an isky max1 cam and a 4" merc crank, EAB heads, and an Edmund's 2x2.
Charlie blocked off the PV's and installed 52 jets, cleaned and replaced other parts as necessary (basic quality rebuild).
I will be home tomorrow and install them.
I will report back how they work out.
For the record, I got a chance to meet Charlie today and he is a class act.
He has a built flathead ona test stand that he runs all his rebuild's on before he ships them.
Chappy

 

Sweet! Yeah keep me posted!


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So I have stumbled across what I believe is the actual problem. I’m not getting any spark at different times. Sometimes it sparks other times it doesn’t. I’m baffled at this point. Just emailed Bubba to see if he can shed some light....


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I would check the fuel pressure. Stromberg’s like Weber’s are very sensitive to too much pressure. Much over 3 to 4 PSI Will cause fuel to blow past the needle and seat and cause a overly rich mixture from the excess un metered fuel. Try a adding a small inline fuel pressure gauge before inlet to the carbs or at the fuel distribution block


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So i decided to run and grab a pertronix. And all is well now. Contact points were sticking upon removal to put pertronix in. Ignition all along? This has been a fun experience. Thanks to all for the comments and replies.


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Good answer if he was running Strombergs. Did you read the title?

 

Put a good 80 miles on her tonight after installing the pertronix. She’s running great.


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You know what they say, “80 percent of all carburetion problems are the ignition”.

 

It’s been in my head this whole time that something wasn’t right with this distributor. Happy I got it figured out!


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That's a pretty looking engine you got there, glad you got it sorted.