Author Topic: Accel. Pump - How tight a fit?  (Read 1210 times)

Offline Glennster

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Accel. Pump - How tight a fit?
« on: September 01, 2008 - 08:23:42 AM »
I rebuilt the old 2 barrel, but I keep thinking that the new Accelerator pump should have been a bit bigger. As I installed it, I remember thinking that it must swell up after it soaks in gas for a while, since it seems too small for the hole it fits in. I originally thought that this thing should fit kind of tight. It did not touch the sides of the hole it fits in. Should it fit kind of tight upon new installation?
Maybe this is why I still have a hesitation on brisk acceleration???




Offline Glennster

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Re: Accel. Pump - How tight a fit?
« Reply #1 on: September 01, 2008 - 08:31:30 AM »
More info, I've got a Carter Carb, tag number 4724s0543 - 18
The rebuild kit is a CARQUEST   P71  1597
Is this right?

I'm beginning to wonder if this was not the right kit, I asked these guys to get me a float for this and they got me the wrong one, it does not fit and it says Holly on it :swear:

Offline Supercuda

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Re: Accel. Pump - How tight a fit?
« Reply #2 on: September 01, 2008 - 07:27:25 PM »
The accelerator pump always seems a little loose on the Carters now. I think that somebody changed specs without telling the carburetor. If the pump diaphragm was leather, it would need some "flaring" done by hand before installation, to ensure a tighter fit. The neoprene (rubber) ones seem to be the ones with the problem. It should fit fairly tightly, and only allow a small amount (if any) of fuel to bypass the pump diaphragm. Which type of pump was in your kit? As far as I know, there was only one size of accelerator pump for the Carter 2 barrel carbs, no matter the size of the carb or engine. This is all based upon memory, as it has been a while since I had to do any work on a 2-V carb.

Offline Chryco Psycho

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Re: Accel. Pump - How tight a fit?
« Reply #3 on: September 01, 2008 - 07:29:55 PM »
look in thew thoat of the carb & make sure fuel is pumped even wioth the slightest movement

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Offline Glennster

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Re: Accel. Pump - How tight a fit?
« Reply #4 on: September 01, 2008 - 08:07:49 PM »
My new one is not leather, looks like neoprene.
I wonder if this was for a Holley carb, I might drop  $17 and get one from Advance Auto. I called Auto Zone and they did not want the tag number from the card to order one. That seems strange :clueless:

Offline Supercuda

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Re: Accel. Pump - How tight a fit?
« Reply #5 on: September 02, 2008 - 07:37:51 PM »
If your kit were for a Holley carb, it would not have worked for your Carter. Like Chryco said, look down the throat of the carb and wing the throttle. There should be an immediate shot of fuel into the carb throat, and it should continue until the pump bottoms out in its bore. If there is a shot of fuel, then it is probably a matter of fine-tuning what you have. On the Carter BBD, the pump stroke can be increased or decreased, to help tune the accelerator pump circuit. Measure the height of the accel pump rod above the top of the carb, and record it for future reference. Then, bend the link, or move it to a different hole in the pump arm (whichever is necessary to get the desired change), to increase the stroke of the pump. This will mean putting more of the pump rod above the top of the carb, and small changes can make a big difference. If no change in performance can be gained, then you put the pump rod back where you found it, and check for another problem.

Offline Glennster

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Re: Accel. Pump - How tight a fit?
« Reply #6 on: September 02, 2008 - 10:06:17 PM »
Good info, I'll continue to work on it.
Thanks!!!