Hesitation upon accelerating.

[moonshine runner]

Good evening all,

Thought I'd post this and get some thoughts from you all about an issue I am having. My 56 Vicky with a 292 has a fresh engine overhaul with 250 miles on it. It also has a 4 barrel Holley 4000 teapot carb that was rebuilt by Mike Suter back in June.

The car also has a rebuilt original Ford distributor with new bushings and double vacuum advance.

Now, I have not done any simple test yet but here's what is happening. Car starts great and runs great except when you are stopped at a light or sign and start to take off and there is a hesitation, then it picks up and runs good.

Saturday while out driving I noticed it has started to pop in the carb from time to time upon acceleration.

Any thoughts on what might be causing the problem? I have been thinking bad cup on accelerator pump, causing it to lean out when I am accelerating from idle.

I was also told to check the timing.

Thanks in advance.

Kevin

[WestCoast]

bad accelerator pump,or slow timing will cause the hesitation , a sticking intake valve will cause a pop out of the carb along with the other two

[Ole Don]

When November comes 'round again, cool weather can affect the tune. Make sure you have heat to the intake manifold. My 312 does not need the heat riser valve on the exhaust, it seems to get enough heat just passing by. If you dont have a pile of money invested in that 56 distributor, try to find a 57 at a swap meet. Then experiment with ported vacuum vs. manifold vacuum.

[parklane]

Originally Posted by Ole Don

When November comes 'round again, cool weather can affect the tune. Make sure you have heat to the intake manifold. My 312 does not need the heat riser valve on the exhaust, it seems to get enough heat just passing by. If you dont have a pile of money invested in that 56 distributor, try to find a 57 at a swap meet. Then experiment with ported vacuum vs. manifold vacuum.

These distributers were available at NAPA a short while ago quite reasonable.

[Talkwrench]

May have just picked up some crud in the fuel and you have a small blockage. Shame with a newly rebuild carb.

Condenser..?

[Blackpearleb434]

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Could be lean on the idle circuit...have you set the mixtures using a vacuum gauge?

[RCM]

Probably bad accelerator pump. Cant tell by experience but have read about it at our forums threads several times. Others will advice better.

[moonshine runner]

Thanks for all the replies. No, I haven't done any trouble shooting yet. I thought I would start by raising the choke flaps and giving the accelerator a pump by hand to see what kind of spray I get.

I have spoken to my local mechanic and he is going to check the timing and see if it's off any.

I will also ask him to check the idle circuit and set the mixtures.

Thanks again everyone.

Kevin

[oj]

Did this hesitation/pop start recently as in it once ran without problem and this has just started? or has it been like this since rebuild?
The reason I ask is that I find the symptoms you are experiencing will occur if the linkage plate attaching to the throttle shaft has gotten loose and rewelded slightly out of phase with throttle blades, so that the blades will open before the accelerator pump provides the squirt. The accelerator pump cam is attached to the linkage plate and if that plate has been rewelded in a slighly retarded position the pump shot will lag the throttle blade opening. i see this on dirt track cars where they won't use a throttle stop and the linkage plate (where your throttle rod attaches to the carb) takes the abuse of a heavy addrenalin-filled foot and they come loose on the throttle shaft.
Just have a looksee if there is a gob of weld or braize on the throttle plate to eliminate that possibility.

[RCM]

This is good info oj. An example photo would be nice.
Thanks on the side.

[Hot Rod Reverend]

good advice OJ.... those plates to open the butterflies are often just simply "peened over" on the ends. Those suckers do need to be tight.

[Ole Don]

A healthy 292 should be timed with a vacuum gauge. They like about double what the book calls for for ignition lead. ACCCKKK! I just remembered, you have a 56 distributor.
I dont remember how much initial lead I gave mine in 1959. I remember doing it by ear though.

[miker98038]

Don's still right. They all like more advance than the book, and if it pings up top, you need to limit the advance. I personally think this was part conservative spec's on Ford's part, and part modern fuel. Likewise about the ambient temperature. The ethanol plays into this. We often forget how often we tweeked the carb and choke by season in the old days. Running a 11:25 to 1 motor on 105 octane leaded fuel, you cleaned the plugs every 500 miles. Or every Friday night.

[moonshine runner]

Originally Posted by oj

Did this hesitation/pop start recently as in it once ran without problem and this has just started? or has it been like this since rebuild?
The reason I ask is that I find the symptoms you are experiencing will occur if the linkage plate attaching to the throttle shaft has gotten loose and rewelded slightly out of phase with throttle blades, so that the blades will open before the accelerator pump provides the squirt. The accelerator pump cam is attached to the linkage plate and if that plate has been rewelded in a slighly retarded position the pump shot will lag the throttle blade opening. i see this on dirt track cars where they won't use a throttle stop and the linkage plate (where your throttle rod attaches to the carb) takes the abuse of a heavy addrenalin-filled foot and they come loose on the throttle shaft.
Just have a looksee if there is a gob of weld or braize on the throttle plate to eliminate that possibility.

Thanks OJ, and the rest.

Well as far as how did it run before, well here's the scoop. I bought the car in September and finally got it home on October 19th. When I got home and backed it off the trailer and took it for a drive, it had a hesitation.

Last Saturday we went for a drive and I noticed it popped once in the carb. We took it out last Sunday and it popped again during hesitation after leaving a stopped position.

As mentioned earlier, I have a document showing that Mike Suter rebuilt the carb back around June.

Having said this, I don't know how the car ran right after rebuild but the engine now has about 250 miles on out.

One thing that I need to do is purchase a shop manual for this car so I will know what the timing sets at and other things.

Kevin

[Blackpearleb434]

250miles...relatively new rebuild so it could have tight valve clearances, retarded timing, lean mixtures or all of the above!!, I would check these three things first such that you have a base to work with....do one thing at a time go for a drive so that you can isolate the cause

[moonshine runner]

Originally Posted by Blackpearleb434

250miles...relatively new rebuild so it could have tight valve clearances, retarded timing, lean mixtures or all of the above!!, I would check these three things first such that you have a base to work with....do one thing at a time go for a drive so that you can isolate the cause

Great starting point. Thanks Blackpearleb434!

Kevin

[darrell]

my teapot has a hesitation when pulling away the pop you got is from lack of fuel mine will do it if i dont give it to her just right.just enough to bug you.

[moonshine runner]

Originally Posted by darrell

my teapot has a hesitation when pulling away the pop you got is from lack of fuel mine will do it if i dont give it to her just right.just enough to bug you.

Hey Darrell,

Yeah, I kinda thought the pop was caused from it leaning out. And what you said about how you "give it to her" when taking off works for me too.

Mine don't always hesitate. It depends on if I soft foot the pedal or get into it a little taking off. If I do that, no hesitation and I don't mean getting on it to the point of squealing the tires.

So, are you doing anything to your teapot since yours is doing that?

Thanks,

Kevin

[darrell]

no i live in the country so not so much stoping and starting.if i lived in the city it would drive me up the wall.i think its just the pump but i have to buy the whole kit,its hard to see how well the pump is working on a teapot.im also thinking of changing my engine this winter as i have a complete rebuild with less than 20,000 on it.my engine is original and is leaking oil here and their uses some and so on .the engine has the new type holley 2bbl which is rebuilt so will leave it on but it will never give the gas milage oy my teapot.

[peglegrice]

Do what they tell you on the distributor. Good winter project, start with about 10-12 degrees initial timing. You'll like it. when you get the distributor check which cam setting it has. you'll want a 12 degree slot. That will give you a total of 34 to 36 degrees total.