Hesitation off idle on newly rebuilt carb

[3twinridges]

This is a Holley 94 8RT carb on an 8BA flathead. Everything soaked in Berryman, kit from Daytona, and some parts from Charlie Price (PV gasket and jet plug gaskets) Tuned it in and it runs rate at 20” with a steady vacuum needle and it idles really well. First blip on the accelerator and it hesitates a little. It recovers and subsequent blips on the throttle and it has no hesitation at all. It’s just that first blip after it has been on slow idle for a minute or so. Any thoughts on the culprit? I am running jets with “52” stamped in them.

JB

[19Fordy]

My 94's have used #51 jets. Could that be the problem?

[flatjack9]

Which hole is your accelerator pump link in?

[Scotty's 52 F3]

I did same to my carb but, also had to make bushings for the throttle shaft. I had to play with the accelerator pump adjustment to get rid of hesitation.


It's been a while so I don't remember which hole it is set at.

[3twinridges]

I put the link in the middle hole, haven’t tried any others but will.

JB

[3twinridges]

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Well I changed the pump link to the hole closest to the shaft as I believe that is the summer setting. Didn’t help.

Then I took the air cleaner off to check the strength of my stream. I have two squirts coming out but the accelerator pump discharge is leaking pretty bad around the gasket which makes me think that I either left that gasket out or it’s the wrong one as I don’t think gas should puddle up around it. I think if that was a tighter fit my stream would be stronger.

Is that a correct assumption, that gas shouldn’t leak and pool around the discharge nozzle?

JB

[flatjack9]

That is correct.

[RalphM]

Do you have the rubber, or leather accelerator pump? I always switch mine out for the leather pumps, seem to work better. When you install them put some Vaseline petroleum jelly on the leather first.

[1952henry]

Try to wriggle the discharge nozzle with your finger whilst the keeper is in place. If it wriggles, either there is no gasket or too thin of one. Some kits had a gasket that was too thin.

[philipswanson]

The accelerator pump bore is probably badly worn or scored.

[3twinridges]

I checked and it had a gasket, so I doubled it up, it helped but something is still not 100% right with that accelerator pump circuit. My stream is not as strong as the stream in my 7RT carb and it still stumbles albeit much less noticeable. I need to go through it again and make sure all of the passages are clean, and make sure I didn’t damage the leather when entering the bore. Thanks for the tip on Vaseline, I used 3-1 but it was pretty thin.

JB

[3twinridges]

So went back through the carb again in several ultrasonic baths and a pipe brush detail. I think my problem was that I was using gaskets too thick on the nozzle bars that interfered with the discharge seating tight. Fixed all that and I had a really strong stream of fuel on both sides. Left fuel in the bowl on the bench overnight and power valve holds. It fired right up and ran well, quick response on acceleration with no stumble.

JB

[scicala]

Good job ! Thanks for posting results.


Sal

[Ken Crans]

Good info... Thanks!