Hot Rod Forum : Hotrodders Bulletin Board - View Single Post - Rochester Quadrajet 4MV Carburetor: Removal, Disassembly, Rebuild (Rookie Level)
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Old 02-07-2011, 09:37 AM
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Hey Cobalt,

Originally Posted by cobalt327
Usually you would expect to see a plastic retainer (shown below). The plastic retainer is a tight enough fit to seal the PP, and retain it in the casting.

I was looking over the pictures from disassembly and it seems the power piston was held down in place using the gasket that lays between the float bowl and the air horn. I tried doing that and it works, as long as the gasket is held down in place and the air horn is quickly placed on top. Otherwise, due to the spring below it, the piston is prone to jump out a bit. I personally don't see this as ideal solution. Any thoughts?

Originally Posted by cobalt327
The retainer shown is a replacement of the original. It is 'split' to allow it to be installed w/o taking the PP apart.
I was looking at what's left in the rebuild kit and found three round gaskets, one rod for the fuel pump, and the accelerator pump cap. The small brown cork gasket fits perfectly in the area where the power piston is placed. However, it wasn't pre-cut in any way so I assume its not for that. Worse comes to worse, I order the bushing.


Originally Posted by cobalt327
An OFTEN overlooked passage that needs to be cleaned, and is often plugged or obstructed, is the small, ~0.028" orifice that connects the secondary discharge port well to the main fuel reservoir.

Because it's on a 'ledge', it's prone to have deposits clog it, and it is hard to see if you're not specifically looking for it.

Be careful to not enlarge this orifice, it is also part of the secondary air/fuel ratio calibration and if made too large, will cause the secondary to go pig rich under extended WOT operation.
I tried looking for these passages but was not able to find 'em. I'll admit Im not very good with the proper terms for different parts so that may be throwing me off. Below is a picture of what I was looking at. feel free to copy and mark as needed.

Thanks for the help and pointers!
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