Rebuilt the carb, but I have a question

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Rebuilt the carb, but I have a question

Postby olds70supreme » Sun Sep 14, 2008 8:29 pm

I recently rebuilt the 2 Bbl carb on my Starfire. It is not original (# does not match book) but is for a 231 v6. I am not worried all that much about originality with this car. The reason I rebuilt it was that on acceleration, it had a "dead spot" just off idle where the engine would literally cut out completely. If I pushed the pedal past that point the engine would increase in speed, but you could feel that something was not right in the way it almost fought against accelerating. So, I rebuilt it, and it performs much better now. However, during rebuilding I came across a part of the carb that I was unsure of its purpose, and also unsure if all the parts were there. That part is shown in the picture. The rebuilding guide mentioned that there would be parts under the cover (held down by two screws), but there were none under the cover on my carb. Does anybody know if these pictures are missing anything?

Image

Image

Thanks.
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1975 Oldsmobile Starfire


Re: Rebuilt the carb, but I have a question

Postby gotmud7 » Sun Sep 14, 2008 11:25 pm

Send me your email address. I just purchased a 2bbl rochester manual off ebay. I remember it talked about this. I'll email you a copy of it. It's in pdf format. 14 pages. I have the same stumble you have off idle on acceleration. I want to fix it before I put on the header!

Mark
gotmud7@aol.com

I went and lookied it up. Shows a "nylon vent valve" under the cover for "late model" carbs. In the picture it looks like a rectangular block with a screw in the middle of it.
The only Vega's that only had a little rust were the ones still on the assembly line.
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Re: Rebuilt the carb, but I have a question

Postby olds70supreme » Mon Sep 15, 2008 8:52 am

Okay, that helps, and you should have a new email. However, it brings up two questions:

1. Does anybody know what constitutes a "late model carb"? Specifically, what years/numbers/applications?
2. What is the function of the vent valve? Is it for use during hot operation,...,...?

Once again, thanks for the help.
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1975 Oldsmobile Starfire


Re: Rebuilt the carb, but I have a question

Postby Kev442 » Mon Sep 15, 2008 12:46 pm

Sure looks like what would be called the accelerator pump on a 4 barrel. Gives a little squirt of fuel when you accelerate to avoid a dead spot...
1978 Olds Firenza x2!
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Re: Rebuilt the carb, but I have a question

Postby olds70supreme » Mon Sep 15, 2008 8:16 pm

Sure looks like what would be called the accelerator pump on a 4 barrel.


Nope, the detail I'm looking at isn't the accelerator pump.
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Re: Rebuilt the carb, but I have a question

Postby gotmud7 » Tue Mar 31, 2009 1:06 pm

I am rebuilding the Rochester 2bbl on my 72 Vega GT now. It is a different carb than the first one in question. The area in question goes to the charcoal canister for emisions. On my 72 there is basically a round hole with a silver ring there with nothing covering it up. Not sure if that is correct or not either. My carb had a Holley rebuild sticker on it. But I don't know when that was from.
The only Vega's that only had a little rust were the ones still on the assembly line.
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Re: Rebuilt the carb, but I have a question

Postby bill1978v8 » Tue May 31, 2016 3:58 pm

I have the same carb and same hesitation issue. Did you resolve your issues?
1978 Monza 2+2, 3.2L V6, Auto
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