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Old 04-09-2019, 06:16 PM   #1
quickmfg
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Default Off-idle Hesitation Advice - 8BA & Holley EBU / 94 Carb

Hello all,

I need some help, I've read about a hundred posts here, but am stuck.

I've got a stock 8BA that someone put a Ford EBU carb on, and has hesitation/stumble just above idle if I slowly open the throttle. Idle vacuum is 20.5" at 475 rpm, running great, then as I crack throttle, vacuum drops to 17" and runs rough. I can bring it out of this funk by choking it with my hand partially. Seems to do fine upwards of 1500 rpm, or when goosed. Accelerator pump likes to be on the 3 hole so I dont get a bog , even when hot. Power valve is not leaking checked on bench and by closing idle screws. Distributor is stock loadamatic, and I start seeing some advance by about 550-600 rpm. #55 jets. I can see plenty of fuel flow from idle holes, and then from off idle holes as I slowly open throttle.

It appears that fuel is dripping from right nozzle bar, but not left as I open throttle. I've read about the air bleed holes in these nozzle bars. See picture, the top nozzle bar holes are either blind, or the hole is so small that the wire from a bread twist tie won't fit through. Are these bleed holes?

The low end torque that my 59A has when I let the clutch out will definitely not be there the way it is now.

Thanks again,

Nick
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Old 04-09-2019, 06:49 PM   #2
tubman
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Default Re: Off-idle Hesitation Advice - 8BA & Holley EBU / 94 Carb

IIRC, an "EBU" is off of a '54 overhead V8, which was also 239 ci, so it should be sized right. I had one on my '51 8BA and it worked fine. Make sure the passages you reference are clear, and then I would look at the accelerator pump, and then double check the power valve. I'd replace it anyway, because known good replacements (think "Charley ny") aren't that hard to come by.
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Old 04-09-2019, 07:25 PM   #3
Phil Gillespie
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Default Re: Off-idle Hesitation Advice - 8BA & Holley EBU / 94 Carb

Quote:
Originally Posted by quickmfg View Post
Hello all,

I need some help, I've read about a hundred posts here, but am stuck.

I've got a stock 8BA that someone put a Ford EBU carb on, and has hesitation/stumble just above idle if I slowly open the throttle. Idle vacuum is 20.5" at 475 rpm, running great, then as I crack throttle, vacuum drops to 17" and runs rough. I can bring it out of this funk by choking it with my hand partially. Seems to do fine upwards of 1500 rpm, or when goosed. Accelerator pump likes to be on the 3 hole so I dont get a bog , even when hot. Power valve is not leaking checked on bench and by closing idle screws. Distributor is stock loadamatic, and I start seeing some advance by about 550-600 rpm. #55 jets. I can see plenty of fuel flow from idle holes, and then from off idle holes as I slowly open throttle.

It appears that fuel is dripping from right nozzle bar, but not left as I open throttle. I've read about the air bleed holes in these nozzle bars. See picture, the top nozzle bar holes are either blind, or the hole is so small that the wire from a bread twist tie won't fit through. Are these bleed holes?

The low end torque that my 59A has when I let the clutch out will definitely not be there the way it is now.

Thanks again,

Nick

Maybe your jets too big? My understanding is a set of 51's are the standard ones to begin with. this is where i would begin along with perhaps new PV.


Phil NZ
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Old 04-09-2019, 07:36 PM   #4
Charlie ny
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Default Re: Off-idle Hesitation Advice - 8BA & Holley EBU / 94 Carb

quick,
My nozzle bar preference is the inverted 'V' design that came on the earlier 94's.
These bars seem to be far more capable to make a good performing 94 than any of the tall bars. Try to dig up some of these early bars and try them....be absolutely sure you use new gaskets...tighten the rear clamp first and try to wiggle the bars...if they are tight then loosen that clamp and tighten the front clamp and check to be sure the bars are tight and also the squirter is not loose, retighten the rear clamp. Doing this insures no vac or fuel leaks that can otherwise drive you batty. I would take this opportunity to also reinstall the link in the middle hole. During the nozzle bar switching thing take the time to gently tap the check plunger under the squitter to be sure it is seated....a very annoying lag occurs if this plunger does not seat properly.
We can go deeper but then we'd all be asleep.

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Old 04-09-2019, 08:40 PM   #5
tubman
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Default Re: Off-idle Hesitation Advice - 8BA & Holley EBU / 94 Carb

Yep, "Charlie ny" is the best; he has the parts and the skills.
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Old 04-09-2019, 10:00 PM   #6
Blastfromthepast
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Default Re: Off-idle Hesitation Advice - 8BA & Holley EBU / 94 Carb

I found from my experience that the accelerator pump dries up and shrinks just enough so you don’t get the right amount of gas needed. They do sell a replacement made of a material That doesn’t dry out and shrink From todays fuel.
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Old 04-10-2019, 08:12 AM   #7
quickmfg
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Default Re: Off-idle Hesitation Advice - 8BA & Holley EBU / 94 Carb

Thanks all. Pump and PV are new from USA kit, and I have excellent flow from pump nozzles.

I have a line on a body from a 7RT carb with the earlier nozzle bars, I will try those and reseating the pump discharge needle, and will report back.

Nick
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Old 04-10-2019, 08:52 PM   #8
motordr
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Default Re: Off-idle Hesitation Advice - 8BA & Holley EBU / 94 Carb

I would try some #57 jets, that’s what worked for me.
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Old 04-10-2019, 09:37 PM   #9
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Default Re: Off-idle Hesitation Advice - 8BA & Holley EBU / 94 Carb

Sounds like a lean issue. What do the plugs look like?
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Old 07-21-2019, 02:31 PM   #10
quickmfg
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Default Re: Off-idle Hesitation Advice - 8BA & Holley EBU / 94 Carb

Hello all,

I know it's been months but I've finally had a chance to get this right. Problem was gasket thickness underneath the nozzle bars and accel nozzle., combined with tweaking the clips underneath the screws holding same. Am running two 56 jets now in an EBU carb, seems good.

The holes in the top of nozzle bars are blind, must be for die casting or something. There ARE air bleed holes in the sides.

Thank you Charlie for the help!

We'll be at the NYSEA Pageant of Steam in Canadaigua, NY in a few weeks, alll are welcome! www.pageantofsteam.org
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Old 07-21-2019, 03:53 PM   #11
flatheadmurre
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Default Re: Off-idle Hesitation Advice - 8BA & Holley EBU / 94 Carb

Also the float level is different from using the Y style Nossle should be 1 9/32.
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