The Stovebolt Site Forums The Shop Area Engine Shop Rochester B parts questions

Hey all, I'm going through my carb on the truck...basically doing a home job rebuild. I've got my carb apart and I noticed a couple of things that I am curious about. It's a Rochester B, 235 base/model, manual choke for reference.

My first question is regarding the accelerator pump. I pulled the accelerator pump out of the carb housing and there was no check ball present at the bottom. I got my flash light out and saw that there were to small holes at the bottom 180 degrees apart. I read that if the carb has these 2 holes, there should be an 5/32 aluminum check ball at the bottom of the hole. I'm pretty sure I'm going to need one in there, but I can't find anybody who sells an aluminum ball in my area. Is there a reason why it has to be aluminum? Can I use a steel ball instead? 5/32 steel balls are available at my local fastener shop. If I shouldn't use steel, then I'll order some aluminum ones on line.

Second question pertains to the needle in the carb. The needle in this carb is all steel, and I've been looking at the rebuild kits and it seems like they all have the needles with rubber tips. I'm thinking the needle in this carb is probably the original? Is there a benefit to replacing the one in the carb with a new one with a rubber tip or am I ok or even better off running it with the steel one?

Everything in a carb has to be corrosion resistant. Like it won't rust. Brass, bronze, copper, stainless steel, aluminum. SS ball or AL ball is OK. "Steel", like carbon steel ball..NO! If it's magnetic, you can't use it.

If you don't mind me saying: When you rebuild a carb, you buy a rebuild kit. You don't by balls and other parts at a hardware store. If you buy the correct kit, use the new needle valve provided. It will also have the ball(s) you need any many other parts that MUST be replaced. Everybody builds their carbs at home. It's good you are doing it. Just do it with a kit. Possibly this one.

Thanks Bartamos...got it on the no steel, the fastener shop sells "Hardened Steel Ball Bearing Balls. E52100 Precision Alloy Steel. Grade 25. Chrome Plated.". I will stay away from them and just get the right aluminum ball, on that note...

Most kits I see do have 1 5/32 and 1 3/16 stainless steel check balls, but I have yet to find a kit that also provides the 5/32 aluminum check ball for the accelerator pump. Apparently it is not required for some Rochester B's out there so they don't include it? Go figure I have the bowl casting that requires it.

There is one old school carb rebuild shop about 30 miles from me...i'll take a trip over there tomorrow and see if they'll sell me the aluminum ball...My carb is only missing that ball. The other two check balls in different parts of the carb are there like they should be.

As far as the needle goes...with the terrible gas we have to run, especially here in California...wouldn't the new rubber tipped needles in the rebuild kits fail faster than a solid metal needle. I can see how a rubber needle would seat better, espcially if there was some crud in the fuel, but I gotta think that super dry gasl we run here would degrade that rubber over time where as the steel needle would be unaffected buy all the additives.

That link I provided to Mike's carburetor shop is good place to email. I have emailed him and get good friendly information. He will know all about what you are asking. He has a video online on B carbs. Good guy. Expert. Send him ALL the numbers on your carb when you ask. There are several models of that carb. He knows them all. I remember him saying that the accelerator pump rubber is ethanol safe, I assume the needle rubber is the same. Ask him that also.
In my opinion, if the steel valve is examined under a magnifying glass and has no wear, that's one thing. Then you have the "seat" it has been matched to. If that is not worn, then that's another thing. If a steel valve set is mis aligned it won't seal. The rubber takes care of that as well as seals better. You will get a new seat with the kit also. What is your aversion to a kit? $22.50?

Thank you...i'll cruise over to his website tomorrow and shoot him some questions.

Was still typing when you answered. Reread. Let us know what he says.

Bartamos, I went to Mike's Shop page and picked up 3 premium rebuild kits and 3 5/32 aluminum check balls, he had a great deal and free shipping. That should be the end of it, no need to send him any questions his website was very good and answered all of my questions.

Thanks again.

Very good news.

I don't think there is supposed to be a ball in the bottom of the plunger bore. There is supposed to be a check valve in the pump assembly itself. All the kits have two balls, one for the power valve and one for the accelerator output check valve.

Hi Truckernix,

I wasn't sure either but I did some research and found this tech tip that describes which Rochester B's need the check ball at the bottom of the accelerator pump bore.

http://www.carburetor-parts.com/Check-Ball-Placement_ep_732.html

Here is a great picture showing the accelerator pump assemble with check ball. See figures 14, 15, 16. Number 16 would be the pesky little 5/32 aluminum check ball I was missing.

http://www.oldcarmanualproject.com/...h1951-B_Dir/MCarbRoch1951-B_Picture8.jpg

OK I am going to have to do some more research! I have wondered myself about those little round holes. I don't recall seeing a ball there in the Rochesters that I have taken apart. So here it is: http://chevy.oldcarmanualproject.com/carb/51rochester/51rcm30c.html Now my GM Rochester manual does not show the check ball but instructs to shake the pump assembly to make sure the check valve is free. I also see further down in this article it talks about the three balls.

There is the pesky ball again, I guess it's needed...I have a feeling they get lost over the years. Not really sure how much it matters if it's missing my truck was running pretty good without it. I'm interested to see how she runs with one in there. We shall see!

About that check ball in the accelerator pump well....

Well, I went through my carb and when I put it back together I placed the ball down in the bore. I put the carb back on the truck and had terrible stumbling off of accelerations. I grabbed the flashlight, pulled the air cleaner, and actuated the throttle...and the accelerator pump was not squirting like it should. It was basically a dribble.

Took the carb off, pull the ball out of the accelerator pump bore, reinstalled the carb...and all seems to be well. Squirting like a champ on hard throttle application.

Guess its really hit or miss as to the proper application of that check ball.

The B1 with two holes at bottom of accelerator pump well, does get one ball in lower hole. That would be three balls in that style carb. If it does not work with that ball, I suspect something else in that carb is plugged up or mis assembled. The total driveability and performance will tell.
For anyone interested, watch this entire video and pay special attention at 25:48 minutes.