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Holley Carb left turn stumble or stall!

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Dr Jay
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Holley Carb left turn stumble or stall!

Post #1 by Dr Jay » Sun Jan 20, 2019 11:34 pm

Over the last 3 months my 390 cfm Holley gives a big stumble during a left turn out of the driveway.
There is an incline then nose drops down and a 90 degree left is pretty sharp under power with traffic bearing down.
I have adjusted the fuel level up and down.
A level on the air horn shows the carb toward the front
of the truck do to engine angle.
The primaries are toward the valvecover.
What will help?
Reorient the carb front to back (hate the linkage setup there)
Center swung bowls?
Wedge spacer leveling the carb?
Thanks!
Blessings,
Dr Jay

1978 F100 Shortie, Lowered front and rear, 300 .030 over, 300 carb head, Clifford, Holley 390
268 Comp Cam, Cloyes, Fuel Inj. exhaust manifolds, MSD 6A, TOD, 9"

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THE FRENCHTOWN FLYER
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Re: Holley Carb left turn stumble or stall!

Post #2 by THE FRENCHTOWN FLYER » Mon Jan 21, 2019 10:11 am

Have you already increased the pump shooter nozzle size? I ask because that is an almost universal need on the 390. With the primaries near the valve cover performing an abrupt left hand turn will cause the fuel to slosh toward the main jets, effectively richening the mixture coming out of the primary side boosters momentarily. Hmmm. This seems counter intuitive to me. I would have thought that a right hand turn would be the greatest chance for a stumble. That is what I see on my drag cars with three sideways mounted Holleys.
Anyway, try a fatter pump shooter if you haven't tried it yet.


I'd avoid mounting the Holley sideways on a street car (except with a Clifford DP split runner intake), even if it means redesigning the linkage.
FORD 300 INLINE SIX - THE BEST KEPT SECRET IN DRAG RACING

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Dr Jay
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Re: Holley Carb left turn stumble or stall!

Post #3 by Dr Jay » Mon Jan 21, 2019 2:20 pm

Yes, I followed your advice way back at installation, 3-4 years ago.
Runs great with the larger shooter.
So generally, with a single plane front to back orientation is the best to minimize this... pain?
I drive this thing every day, all day.
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Blessings,
Dr Jay

1978 F100 Shortie, Lowered front and rear, 300 .030 over, 300 carb head, Clifford, Holley 390
268 Comp Cam, Cloyes, Fuel Inj. exhaust manifolds, MSD 6A, TOD, 9"

1986F150six
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Re: Holley Carb left turn stumble or stall!

Post #4 by 1986F150six » Mon Jan 21, 2019 3:08 pm

Dr. Jay, how close to Sheffield [Shoals area] is "North Alabama"?

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Dr Jay
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Re: Holley Carb left turn stumble or stall!

Post #5 by Dr Jay » Mon Jan 21, 2019 6:38 pm

Huntsville/ Madison
I have folks in Muscle Shoals!
Blessings,
Dr Jay

1978 F100 Shortie, Lowered front and rear, 300 .030 over, 300 carb head, Clifford, Holley 390
268 Comp Cam, Cloyes, Fuel Inj. exhaust manifolds, MSD 6A, TOD, 9"

wallen7
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Re: Holley Carb left turn stumble or stall!

Post #6 by wallen7 » Mon Jan 21, 2019 7:19 pm

You might want to check the accel pump cam position and linkage. The cam has a 1 and 2 position. Also you can get different cams with different profiles.

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THE FRENCHTOWN FLYER
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Re: Holley Carb left turn stumble or stall!

Post #7 by THE FRENCHTOWN FLYER » Mon Jan 21, 2019 7:33 pm

Dr.,
That is a beautiful truck.
FORD 300 INLINE SIX - THE BEST KEPT SECRET IN DRAG RACING

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Dr Jay
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Re: Holley Carb left turn stumble or stall!

Post #8 by Dr Jay » Tue Jan 22, 2019 9:25 am

FrenchtownFlyer
I’m excited you like it.
Near glacial speed on improving over the years.
Working on it has been a oasis for me as life has rolled in and out.
My present setup was inspired by this forum.
Thank You!
Blessings,
Dr Jay

1978 F100 Shortie, Lowered front and rear, 300 .030 over, 300 carb head, Clifford, Holley 390
268 Comp Cam, Cloyes, Fuel Inj. exhaust manifolds, MSD 6A, TOD, 9"

1986F150six
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Re: Holley Carb left turn stumble or stall!

Post #9 by 1986F150six » Tue Jan 22, 2019 10:41 am

Dr Jay wrote:Huntsville/ Madison
I have folks in Muscle Shoals!


And I have folks in Huntsville! :lol:

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Dr Jay
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Re: Holley Carb left turn stumble or stall!

Post #10 by Dr Jay » Sat Feb 02, 2019 6:27 pm

New set up!
Not only eliminated the left turn thing;
but, runs better. Great advice, easy fix in 2 hours!!
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Last edited by Dr Jay on Sat Feb 02, 2019 10:41 pm, edited 1 time in total.
Blessings,
Dr Jay

1978 F100 Shortie, Lowered front and rear, 300 .030 over, 300 carb head, Clifford, Holley 390
268 Comp Cam, Cloyes, Fuel Inj. exhaust manifolds, MSD 6A, TOD, 9"

pmuller9
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Re: Holley Carb left turn stumble or stall!

Post #11 by pmuller9 » Sat Feb 02, 2019 10:21 pm

Did the new setup cure the problem?

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THE FRENCHTOWN FLYER
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Re: Holley Carb left turn stumble or stall!

Post #12 by THE FRENCHTOWN FLYER » Sat Feb 02, 2019 11:04 pm

Dr Jay wrote:...
Not only eliminated the left turn thing;
but, runs better. Great advice, easy fix in 2 hours!!
FORD 300 INLINE SIX - THE BEST KEPT SECRET IN DRAG RACING

F-250 Restorer
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Re: Holley Carb left turn stumble or stall!

Post #13 by F-250 Restorer » Sun Feb 03, 2019 12:27 pm

So, am I the only one that can't figure out what 'new set-up' means? I'm sorry, but I see where you said 'easy fix in two hours,' but does that mean that changed the position of the pump cam, got a new one, or acquired a new carb?

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Dr Jay
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Re: Holley Carb left turn stumble or stall!

Post #14 by Dr Jay » Mon Feb 04, 2019 4:07 am

Sorry guys, I rotated the same carb. Now the primaries are oriented to the front of the motor. Previously I ran with the primaries close to the valve cover. The stumble was only on left turns. Straight line acceleration and Rt turn acceleration were excellent. This made me prioritize Frenchtown Flyer's thought about never setting a holley sideways unless it was a dual port intake.
I used a squarebore throttle linkage bracket from summit I found in my left over part drawer. Cost for fix... zero.
Last edited by Dr Jay on Mon Feb 04, 2019 4:14 am, edited 1 time in total.
Blessings,
Dr Jay

1978 F100 Shortie, Lowered front and rear, 300 .030 over, 300 carb head, Clifford, Holley 390
268 Comp Cam, Cloyes, Fuel Inj. exhaust manifolds, MSD 6A, TOD, 9"

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Dr Jay
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Re: Holley Carb left turn stumble or stall!

Post #15 by Dr Jay » Mon Feb 04, 2019 4:11 am

This was my old set up.
Exact same parts except throttle cable bracket.
7DAB084F-7474-4351-8384-9D60BFCA6E1C.jpeg
PS: fuel level adjustment was mandatory after swinging to the new position. Carb mounting pad tilts to rear and the sight plug is now on passenger side. You get the idea!
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Blessings,
Dr Jay

1978 F100 Shortie, Lowered front and rear, 300 .030 over, 300 carb head, Clifford, Holley 390
268 Comp Cam, Cloyes, Fuel Inj. exhaust manifolds, MSD 6A, TOD, 9"

1986F150six
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Re: Holley Carb left turn stumble or stall!

Post #16 by 1986F150six » Tue Feb 05, 2019 1:32 pm

Looks good, Dr. Jay! :thumbup:

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Dr Jay
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Re: Holley Carb left turn stumble or stall!

Post #17 by Dr Jay » Wed Feb 06, 2019 7:12 pm

Thanks 1986F150six!
On to that weird sound coming from the bellhousing while idling in neutral with the clutch out.
Blessings,
Dr Jay

1978 F100 Shortie, Lowered front and rear, 300 .030 over, 300 carb head, Clifford, Holley 390
268 Comp Cam, Cloyes, Fuel Inj. exhaust manifolds, MSD 6A, TOD, 9"

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Re: Holley Carb left turn stumble or stall!

Post #18 by THE FRENCHTOWN FLYER » Wed Feb 06, 2019 7:55 pm

Are you sure the throw out bearing is not contacting the clutch fingers? Maybe try a weak helper return spring on the clutch fork?
FORD 300 INLINE SIX - THE BEST KEPT SECRET IN DRAG RACING

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Re: Holley Carb left turn stumble or stall!

Post #19 by Dr Jay » Thu Feb 07, 2019 12:16 am

Frenchtown Flyer, well it sure sounds like that.
A few related details, I use a TOD (floor shift 4speed with 4 as an overdrive) with a 3.70 gearset and I get to that OD by 50mph or so.
That technique really makes that 3 speed gearset with the OD seem like a toploader. I swapped to a brass pilot bearing do to a consistent failure of the roller bearing type. I thought I was breaking them at installation while I piddled around getting lined up laying on my back rolling that trans jack around struggling to get the input shaft in the pilot bearing.
Now the pilot seems to be dragging the input shaft along with the flywheel when the clutch is disengaged. Going into reverse, really get a big grind. With the truck stopped I go to third to stop the input shaft from spinning to get a good shot to get into reverse or first.
with all that said, now I get this sound that comes from the bellhousing, stopped with the trans in neutral and the clutch engaged.
It can be a big rattle rumble, a lot like a bad throwout bearing with the clutch depressed.
My plan was to pull the trans and go back to the roller pilot, replace the throwout bearing. I will now work that return spring idea for a real fix. What do you guys think.
Blessings,
Dr Jay

1978 F100 Shortie, Lowered front and rear, 300 .030 over, 300 carb head, Clifford, Holley 390
268 Comp Cam, Cloyes, Fuel Inj. exhaust manifolds, MSD 6A, TOD, 9"

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Re: Holley Carb left turn stumble or stall!

Post #20 by Fordman75 » Fri Feb 08, 2019 8:47 pm

It could be the transmission's input shaft bearing too. My NP435 in my old 78 F150 4x4 had that problem.
Ted

54 Ford F100/F150 4x4
300, NP435 4spd, NP205 transfercase

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Shorty
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Re: Holley Carb left turn stumble or stall!

Post #21 by Shorty » Fri Feb 08, 2019 9:02 pm

when I had that TOD four speed in my 83 I had a similar problem, hard to get into gear, grinding, hard shifts. The problem was in the push rod for the hyd clutch master cyl, there seemed to have been a threaded section for adjustment that had stripped and pushed together. I welded in a nut and new threaded section, the truck was a pleasure to drive, no grinding into first or reverse from a stop. My .02$, worth checking before you pull the tranny.
85 F150 on 78 bronco frame C6 np205 welded dana44 front, trussed posi nine inch rear. EFI exhaust manifolds into one 2 1/2" rolls on 35x12.5x15 Maxxis Trepador.

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Dr Jay
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Re: Holley Carb left turn stumble or stall!

Post #22 by Dr Jay » Sat Feb 09, 2019 7:18 am

Fordman75 I’ll check that input bearing. Thanks
Shorty the old 78 has a z bar and mechanical clutch fork. No hydraulics back then.
I’ll examine the linkage for damage. I’ll check for full clutch release. Good idea!
Blessings,
Dr Jay

1978 F100 Shortie, Lowered front and rear, 300 .030 over, 300 carb head, Clifford, Holley 390
268 Comp Cam, Cloyes, Fuel Inj. exhaust manifolds, MSD 6A, TOD, 9"

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Re: Holley Carb left turn stumble or stall!

Post #23 by THE FRENCHTOWN FLYER » Sat Feb 09, 2019 2:04 pm

My '85 van exhibited similar problems. After a clutch and slave cylinder change did not help I discovered a two-foot section of floorboard was never welded to the firewall. Only a line of sealer was hiding the problem. That was allowing the firewall to flex when the clutch pedal was depressed, using up about half of the pedal travel. Welded it up - problem fixed.
FORD 300 INLINE SIX - THE BEST KEPT SECRET IN DRAG RACING

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Re: Holley Carb left turn stumble or stall!

Post #24 by Dr Jay » Tue Apr 16, 2019 9:56 am

I got on that rattle idling in neutral problem on Monday.
I replaced the flywheel to expedite the machining delay. New clutch kit (Summit). Pilot bearing had gained .060” inside diameter on the transmission side. The engine side gained .020”! Bronze dust was all over bell and block plate. Swapped to a Timken roller. The input seemed undamaged and the timken had a nice fit.
The throwout was touching the diaphragm fingers.
Went looser on the clutch fork actuating rod adjustment. The return spring can now
pull the throwout bearring off of the fingers.
Much better on my rattle but now I hear a new sound.
Sigh...
A noticeable intermittent rattle. Maybe from the starter? Back to work!
FE426B4F-3AB1-45C7-94A5-86A8AA93DF97.jpeg
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Blessings,
Dr Jay

1978 F100 Shortie, Lowered front and rear, 300 .030 over, 300 carb head, Clifford, Holley 390
268 Comp Cam, Cloyes, Fuel Inj. exhaust manifolds, MSD 6A, TOD, 9"

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