Rochester 2g accelerator pump

Background:

FSM page 119 E-25 bottom of page.

quote"
The accelerator pump plunger has a vapor vent ball in its head. This ball and its seat form a valve to vent any fuel vapors which form in the pump well to the fuel bowl during hot-engine operation. This ensures that the pump well and passages will be primed with solid fuel at all times and improves accelerator pump action. The carburetor is internally vented through a hole in the air horn.
unquote"

My camera won't take a readable pic but on page 121 Fig.E-21 it clearly shows item 6 as Vapor Vent Check Ball and it's built into the accelerator pump.

My question is, where can I find this type of pump. All the parts houses here are no help (computer) doesn't show and I cant find it on-line. My last two rebuild kits don't have the pump with the ball in it. Any help appreciated. Tnx.

 

The GM Delco p/n for the pump is 7032880.
Listed for all the 2G carbs; don't know if it has the feature you're asking about.
The originals all used leather cups, not rubber.
I have a leather cup in mine, and I'm 90% sure it doesn't have that feature.
I suppose ordering a kit and/or pump and doing a visual might be the only way.
The unopened Carquest kit I have here does not come with the pump.

 

Tnx jpflat2a for comment. I do remember the ball in the old pumps 50's-70's and leather cups but can't get them anywhere. Did they decide this ball pump was not really necessary and stop making them? Maybe I should just forget about it and use what I can get. I can get the blue cup for the pump for use with this new fuel but not the pump assy.

 

I don't have the answer to your question.
I suppose the pump is the same for the Buick and Chevy V8 applications as well.
Maybe a carb shop/rebuilder would know the answer.
Otherwise, boneyards and tearing apart carbs could be in your future.

 

so when rebuilding the pump with the ball inside you would just switch out the cup, isn't the ball supplied in the kit holding the fuel so it's there at all times? on ther hottest of trail days I get a strong shot of fuel must/maybe not really needed.

 

different ball Steve
this one is built into the pump cup. not the discharge ball.

 

Hmm. When i rebuilt mine - the accel. pump has a single ball (looks like a ball bearing - maybe 1/8th" dia.) that sat under the pump assy.

Are you saying there is another ball in the carb?

 

What Walt is referring to is a ball that is part of the pump assembly, not the check ball that sits under the pump assembly. Two different things.

 

Walt, do you have the carb. number? I have what 'was' called a line nine manual from 1979.I MIGHT be of some help.

 

I have no number. the carb is the same that was on the Tux when I bought it in 1970. 2g with manual choke. Tnx for help.

 

7026082
7027082
7041185
7026086
7026089
7027089
7041186
all the Delco/Rochester/GM carb numbers we used for V6
FYI, these all use the same pump part number I listed above.

 

Geez you are quick.

 

The search is still on. If I can find it I will post the info. Tnx for the help as always.

 

I did some looking in my book and this is what I found,a pic of the check ball and accel pump and the discription that you have in your 1st post is what is in my book also. The book goes on to say some models use a synthetic "floating" pump cup which uses no vapor vent ball. The up and down movement of the "floating" cup on the pump head either "seats" to provide it solid charge of fuel on the down stroke or unseats on the up stroke to allow fuel to flow by the cup and fill the pump well. The cup remains unseated when there is no pump plunger movement to vent vapors in the pump well.Maybe this is what the aftermarket is doing????

The date of pub. is may 1973.

 

I think this is the answer as to why I cannot find the one with the ball. They simply re-designed it and is N/A or no longer necessary with the newer simpler design. Ok I accept this since it still functions the same and provides the same venting of vapors. Thank you for this information. Glad you didn't give up Dan. Really appreciate this.

 

Glad I could help.:tea:

 

I took a close look at one I had apart this weekend and the accelerator pump is just as Dan D described.

 

nickmil I did the same thing today. After seeing the pump structure and applying the info from dan d, it makes things more logical. There was probably a change bulletin made on this but who knows how to find it. Anyways it is here (the info) and the research done by you, dan d and others, so it's logged down now. Very much appreciated.