The Stovebolt Site Forums The Shop Area Engine Shop Rochester carb power piston

Even though I am a year or two away from a running truck, I am doing some small projects to provide a diversion from the endless body prep. I have three Rochester carbs I am trying to make one good one from. It may be an exercise in futility since all three have visible gaps between the airhorn and bowl no matter what combination I put them together in. One question I cannot see answered in the archives is the differences in the power pistons. 2 of the carbs have a more solid looking piston with a tit on the end. These look like the pistons shown for a auto choke Powerglide carb. The third power piston has the longer thin rod on the end. Either one looks like it will lift the ball in the power valve. Are these power pistons interchangeable?
Chuck

I have seen those thicker pistons also & it seems to me it would be defeating the purpose. These re builders put them in thinking it is more durable. If you notice every one like that has some kind of rebuild sticker or stamping, & the metal tag is gone. The tiny rod goes in & knocks the ball off the seat letting more gas go through. A thicker rod or one that blocks the hole is not right. I would use the original thin one.

The difference in the power piston is explained here:
http://chevy.oldcarmanualproject.com/carb/Rochester/9D95p01.htm

Don't mix the power springs because they are different too.

Thanks for the info guys. I probably should have included that these carbs I have are the 1 1/2" 235 units. I am still a little puzzled because that manual says they started using the thinner rod piston in 1953. Was the thicker solid piston used in the later 235 carbs?

Chuck