VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1929-1932 1931 Updraft carb question

Helping my dad here on his 31. We were having carb issues, so i took his spare home to rebuild. No biggie, I've done lots of carbs, but nothing this old. I'm at the point of reassembly but the pump jet is my question. I've taken it apart to clean and the instructions say not to loose the ball inside...well there is no ball in this one. The rebuild kit does have a steel ball included, but not having one to compare to to verify it's the correct ball I don't want to put it in and have it wrong. The ball measures .126 so approx an 1/8". If this is not the correct size, does anyone know what is?
Trying to get this back on the road for the big VCCA meet in Lake Geneva next month
Thanks

Hi There and welcome to Chevy Chatter. Nice to have you with us.

The ball that is in the repair kit is not correct because it is way too large for the pump jet.

On the Carter 150-S carburetor pump jet, some of the pump jets had the check ball and some of the pump jets did not.

JY dog,
Thanks. It is a 150-s still has the brass tag. Is there anyway of telling if it needs the check ball?
Here's a pic of it if that helps.

All of the pump jets look the same, with or without the ball check.

Hello Jy D,
Would you tell us what the purpose for a check ball be within the carb pump jet assembly. If the ball is not necessary in some carbs but found in others, could it be because of anticipated use in different regions of the world? I am thinking about the rear main bearing check ball and it's need for being only during times when parking up steep hills, other times-not needed. The more I understand about the workings of the updraft carb, the better I'll be at troubleshooting and adjusting them. Thank You

The ball is to seal the pump jet so gas can be drawn into the accelerator pump. Without the ball the jet will allow air to be drawn in instead of gas. There is another ball valve on the gas intake that sticks down into the gas in the float bowl. That one opens when gas is drawn into the pump cylinder and closes so gas squirts when the throttle is opened quickly.

Great i"m learning more about these carbs. Since mine doesn't have the check ball, as I safe to assume I can finish my clean up of the carb and reassemble?

You can reassemble the carb. without the check ball and you should be okay. I have seen several new old stock 150-S carbs. without the check ball in the pump jet. I also have some new old stock pump jets in stock and they don't have the check ball either. I have tried several 150-S carbs. without the ball check and they seemed to perform just fine.

Excellent and thanks.
I spoke to my dad about this last night, and he said I should see your name, JY dog and Chipper as he said you two are the experts with these 31-32's.
Carb seems very straight forward for the rebuild, is there anything else I should know about these?

A couple of thoughts off the top of my head:

Check for a hairline fracture in the brass bowl.

Check the low-speed idle screw and see whether the pointed-end has any "markings" on it. (From being turned in too tightly.)

Check the butterfly shaft to see if there's any looseness in the shaft bushings through the body. (This allows air to leak in.)

Check that the bottom base of the carburater is FLAT. (Any warping here is more air leaking.)

Hi everyone,JD,I also have a '31 ,Coach ,with a rjh-08 updrft carb,is this the same or similar to the carb you all are talking about? I think one of you guys rebuilds these if I am not mistaken.Can you tell me is this an expensive undertaking and how long would it normally take? My car runs fairly well but horrible milage.I have gone through and done all other suggestions from the members, so now I am thinking of doing the carb rebuild. Maybe a different carb would be the way to go ?Thanks,Jay

Jay,
I have sent you an PM. Look for the flashing red envelope.

Yes, the RJH-08 Carter is the carburetor that we are discussing....mainly the model 150-S.

Chipper and I both rebuild carburetors.

Turn around time on my end is three days or less.

Both Skipper and I have years of experience rebuilding these old Chevy carburetors and do a good job. If you need your carb back in the next couple of weeks, send it to Skip as I will be on the VCCA Mid-America pre-29 tour in Indiana next week.

A word to the wise: if you have your carburetor rebuilt try to be sure that the rebuilder knows what they are doing, have the specifications, special tools and replacement parts. Both Skip and I can tell you of carburetors we have had to repair after other rebuilders (some that advertise in major publications) have screwed up the rebuild and the customer (had the audacity to charge over $ 500 for the botched job).

The brass bowl has s make on it, but it doesn't leak. The low speed idle looks good. The butterfly shaft has very slight play side to side, but i'm putting a bushing in to keep it from moving. Base is flat, took care of that before cleaning. Fingers crossed, hope to try it out this weekend.

Thanks again everyone.