jeffsfleet

Hello All. I'm rebuilding the Rochester 2 Jet (2GC) out of my 1970 Cutlass with a 350R. I have purchased a brass float to replace the original plastic one. The question that I have is what do I set the float level and drop at? My shop manual has specs for the plastic float only, and they measure it at a different location than the brass. The carb kit instructions have different instructions depending on what year, and the older (1967ish) shows the brass float with different measurements for the 330 and 400 engines. I figured I would split the difference between and set it between the 330 and 400 specs. Any input you all have would be great.
Thanks,
Jeff

MDchanic

Hmmmm... I've never swapped floats in a 2GC, only done QJs, and you measure from the same point. I'm surprised that the float doesn't have a measurement surface that approximates the one of the plastic float.

Pictures might help if nobody knows off the top of his head.

- Eric

70Wcars

You should be OK at the setting you are going to use. Measure from the flat of the float, not the seam. One thing I have seen with those carbs is be SURE to use the same gasket between throttle body and bowl casting. Your kit probably has two gaskets or more to pick from. There was an internal metering of some kind...old memory not too sharp...and I do know the wrong gasket will cause all sorts of idle issues.

Hope this helps

Danny

MDchanic

+1.

I don't think these gasets can be reversed (like some carbs), but there is a slight difference in the position or presence of one or two small holes, and if they're blocked, coche no va.

Line up your original and each of the others and hold them up to the light to be sure all the holes are the same.

- Eric

jeffsfleet

Sounds good guys! We'll give it a shot and see what happens.
Thanks!

BILL DEMMER

the brass floats were measured at the sharp edge of the seam, with the air horn to bowl gasket installed. set it to 9/16" (18/32") tolerance is +/- 1/32" float drop can be set to the spec. you have as long as it doesn't rest on the bottom of the bowl.


bill

jeffsfleet

Thanks Bill. That's exactly what I set the level at. I have the drop set to the spec provided, but I think I hear it hitting the bottom of the bowl when I shake the carb. I'm gonna pull the airhorn off tonight and readjust it.

Octania

Other than being able to open far enough if need be, why is float DROP a concern?

When is there going to be that low of a fuel level?

jeffsfleet

Drop is not only important to prevent the float from resting on the bottom of the bowl (I agree, this probably won't happen often) but also it allows the needle to open fully in order to keep up with fuel demand. If the drop is set too high, the carb may starve the engine for fuel.