The Stovebolt Site Forums The Shop Area Engine Shop Help - Rochester B Model Carb - Stuck Power Piston

I don't know if I have this diagnosed right or not, but here goes...

SWEET came over and helped me get my 57 chevy truck started the other day. My carb was completely filled with a mix of water and old nasty gas. Lots of whitish corrosion and gunk. I ordered a rebuild kit from ACTP via the link here and also a new float (though mine seems to "float" in hot water).

At any rate, I watched several videos on the web concerning the rebuild of one of these models. Seemed straight forward, right until I got the point where you remove the "power piston," the tall brass rod on the left in this photo: B Model Power Piston

The issue is, I have tugged, twisted and pried on this soft brass barrel trying to get it out. All I have done is bugger up the super soft brass. It won't budge. As I understand it, there should be a spring encased in the other end of the brass tube that you can just see the top of in the photo. It is also supposed to be able to move freely up and down during operation.

Has anyone encountered this issue? How did you solve it? I know if I pull on it with enough force, I'll end up shredding the brass and ruining what is likely a "might as well get a new carb" part.

I have used a two-day soak in PB blaster, steaming hot water, and WD 40 to try to get it to budge. Nothing. Tried hitting hit down into the carb body further too - No luck.

Is it possible some models of these were pressed in? Anyone have a manual that would help?

This is on a 235 inline 6.

The name stamp on the carb, if it helps...
Model

Thanks in advance.

Jim

Jim,

That looks stuck. You might try a heat gun on it. Maybe you could drill and tap the shaft and use a little home made slap hammer on it.

Good news is that if you destroy it, the Rochester B is so common that folks are giving them away.

Ah,

Well, that's good, I guess. I just saw a previous post that included the 1951 version of the carb's manual. It showed a close-up of the power piston (which is supposed to move, of course). Also showed that you have to check to make sure the correct angle is on the seat. I have already buggered up that angle, so I guess I might as well go for broke and yank the danged thing out.

And start looking for a donor carb...

Thanks for the reply!,

Jim

Get some Kroil, soak it for a few days, than warm up the area around the piston with a propane torch. Don't overdo it- - - -just hot enough to make a drop of water sizzle when it's dripped on there. It should free up, but if you've already buggered up the piston, you might have also damaged the housing. I think I've got a couple of junk Rochesters. Email or PM me.
Jerry

Based on how you described the carb to begin with and now with a stuck piston, I'd chunk it and start with another one. Heck, anything you started with would probably be better than yours.
There's probably some pitting in the body too, so you're going to have problems with it even if you get the piston out. Like Kurt51 says, they're giving away old "B" models. Get yourself another good one and start fresh.

Just my opinion and worth every penny you paid for it.

Roger that...thanks for the advice.

Jim

Fourbrads: I had the exact same problem with my rochester b carb. Mine was so solid that I didn't believe that it could possibly come out. After failed attempts with PB Blaster and WD 40 and vise grips, I finally grabbed my wifes' hair dryer, putting heat on the piston and surrounding area. After putting some heat on it I put the end of the piston into my bench vise and slowly started twisting the carb back and forth (keep a hold on the carb so you don't break the piston). The piston finally started rotating back and forth and I slowly twisted the carb until I worked the piston out. After cleaning the hole I pulled the spring out and started the rebuild. The piston know moves very freely with the same spring. Good luck!

Thanks oldchevy

I appreciate the advice. Will give this a try tomorrow and let you know how it goes.

Jim