Accelerator Pumps

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Bruins_Fan
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Accelerator Pumps

Post by Bruins_Fan »

I've been getting some hesitation when I stomp on the gas pedal on my '66 110 PG. I did some research and looked at the accelerator pumps with the air cleaner removed. I'm not seeing any squirts of fuel at all when the gas is punched pretty hard. Obviously, you shouldn't need to "floor it" to have those squirt fuel, correct? I'm thinking both must be shot and need to be replaced.

I also read I'm better off going with the Viton cups from John Sweet if I can get them, rather than those from Clark's.

Any additional thoughts? Thanks guys!

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Last edited by Bruins_Fan on Wed Oct 07, 2020 11:01 am, edited 1 time in total.
'66 Monza Convertible 110hp Powerglide

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Re: Accelerator Pumps

Post by Bruins_Fan »

I should mention if it matters, appears I have '65 carbs on my '66.
20201007_140554.jpeg
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'66 Monza Convertible 110hp Powerglide

joelsplace
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Re: Accelerator Pumps

Post by joelsplace »

You are correct. Slow movement of the throttle shouldn't produce squirts but anything more that really slow should. Verify the check ball is free in the plunger and not missing. The check ball keeps it from squirting with slow movement.
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66vairguy
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Re: Accelerator Pumps

Post by 66vairguy »

The 65 carburetors are preferred to the 66. The 66 carbs have slightly lower emissions at idle, but the revised idle circuit in 66 will not tolerate any corrosion in the internal passages. I've had to pitch a few because of that problem as it's not practical to repair.

That said a good working 66 carburetor is fine if the idle works.

The original "black" accelerator cups tend to get hard and stop working after about five years.

The blue Viton accelerator cups are now preferred, time will tell how they hold up. Calif. Corvairs also sells the blue Viton cups.

erco
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Re: Accelerator Pumps

Post by erco »

joelsplace wrote:
Wed Oct 07, 2020 2:45 pm
You are correct. Slow movement of the throttle shouldn't produce squirts but anything more that really slow should. Verify the check ball is free in the plunger and not missing. The check ball keeps it from squirting with slow movement.
Check ball??

Do you mean the pump discharge needle? Or is there a ball in '65 carbs?

joelsplace
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Re: Accelerator Pumps

Post by joelsplace »

There is a check ball in the plunger.
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azdave
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Re: Accelerator Pumps

Post by azdave »

I've put the blue Viton cups in about 10 carbs so far. None have more than about 2 years use on them yet so can't really tell how they will last but no issues so far. I happened to get mine from a CA Corvairs when ordering other parts but I think John Sweet has the better deal if that is all you are buying. The shopping cart at CA Corvairs charges $11 to ship a $4 part that should go First Class Package for under $4.
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Re: Accelerator Pumps

Post by Bruins_Fan »

All good information. Much appreciated!
'66 Monza Convertible 110hp Powerglide

erco
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Re: Accelerator Pumps

Post by erco »

joelsplace wrote:
Wed Oct 07, 2020 10:31 pm
There is a check ball in the plunger.
Oh THERE it is! I've always replaced the whole plunger as an assembly, never knew about it. My knowledge base is severly hampered since I have fewer than 113 Corvairs. (Hangs head in shame) :chevy: :chevy: :chevy: :chevy:
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Re: Accelerator Pumps

Post by Bruins_Fan »

I'm just hoping I can take the carbs apart and get them back together in working order! I do have Bob Helt's carb book, but this will be my first time with any carb disassembly.
'66 Monza Convertible 110hp Powerglide

joelsplace
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Re: Accelerator Pumps

Post by joelsplace »

Bob's book is the best.
Don't feel bad it was many years before I realized that ball was in there.
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Re: Accelerator Pumps

Post by 66vairguy »

You may need to replace the top to bottom carb gasket. DO NOT overtighten the screws when you assemble it. I find the Clark's gaskets thicker than most carb kits and after I tighten the screws I wait a day and re-tighten them after the gasket compresses.

Don't over tighten that hold the carburetor to the manifold. The shop manual has the torque spec. I put a flat and lock washer under the nut to protect the carburetor and they don't come loose.

If you remove the carburetor from the manifold you'll need a gasket on top and below the plastic spacer - make sure the plastic spacer is not cracked. Some don't use gaskets at the carb to manifold - to each their own.

If you need new carb. screws, Clark's has a kit with the correct type and sizes.

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