Any idea how that idle vent valve is supposed to work in 64 Rochester 4GC? There is nothing in 64 Shop Manual and nothing in 64 Delco Rochester 4GC Bulletin. I assume open when idle and closed when gas pedal is pressed ?

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I kindly ask anyone who has original Rochester in his 64 to check if there is that idle vent valve in carb. Small plate in my carb says 7024031 so it is original 64. Thank you in advance.

I have what appears to be the same 4GC in my 62 deville, but I don't know what it does nor does the repair manual really give much insight.  

Thanks Luke

but I did not catch if your carb has that idle vent valve which I am pointing in photo.

I would like to find out if that was in 64 original Rochester carb of not.

It does indeed.  Vent valve and that actuating tang.  The manual says 

-position fast idle cam so that fast idle screw is on the highest step of cam

-vent valve actuating tang on pump lever should be contacting vent valve so that the rubber disc is just off it's seat

-to adjust, bend actuating tang

Thanks Luke. Do you mean 62 factory service manual?

Yes, for 62, it is a a different OEM number for 64 but I have gone and looked at 64-66 4GC's but I don't think there is much between them.  The remans available online for 7024031 have the tang and idle vent valve, and the purpose and setup is surely the same.

I was watching this thread because I wanted to know what it did too!   



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