The Stovebolt Site Forums The Shop Area Engine Shop Rebuilt Rochester B Air Horn Hole

I just bought a rebuilt Rochester Model B that has a small hole drilled in the air horn. I was assuming that the hole should not be there until I ran into this on ebay:

http://cgi.ebay.com/ebaymotors/ws/e...=4504440863&rd=1&ssPageName=WDVW .

It is a Model B with the same hole drilled in the horn that my rebuilt one has. Please look at the upper left photo of the left side of the carb to see the hole drilled in the air horn below the choke shaft. Does anyone know what the holes are for?

Thanks for your help.

Jon

Bowl vent? Brian

Well, I can't remember, but somone posted about that a while back. I have 3 B's and one has the same hole.

Thanks Dave & Brian,
I tried to locate that topic in the forum and couldn't find it. Do you have any idea what keywords I should try besides Rochester + Model + B?

Dave, have you tried to run your B with the hole? It seems as if that the hole would cause the carb to flow lean due to the vacuum leak it creates. In addition, I am not crazy about the amount of dust that would be sucked into the hole.

I think I need to plug the hole. However, I am not sure how to plug it. Anyone have any ideas?

Jon

My local Ace Hardware store has all different sizes of plastic and metal hole plugs - some are pretty small.
A plug like that might work!
Or a small piece of lead shaped into a ball the size of the hole, inserted in the hole and held on the back with a tap on the front from a small hammer, to form fit it to the hole.
I looked at several old carbs I have here and none of them have a hole in that spot, but that doesn't mean that the hole shouldn't be there. General Motors used several suppliers for their Rochester B Carbs and even though they were "B" carbs there was differences between them. All of them did have an air hole somewhere on the air horn. Most had two air holes, one on each side, or front and back.
I can see where it probably is supposed to be there, but you could try to plug it and see what happens. I think you will find it should be open - as a vent.

The B with the hole was on my 49 w/216 when I bought it. I put a kit in it and it ran ok. I finally ditched it for a carter YF, but I don't think the hole had anything to do with my carb problems(typical B, airhorn warped, running rich). I do remember asking someone about it when I did the kit. maybe call Carbking at his shop, he would know, and seems to be nice to talk to.

Thanks Guys,

I think I'll give Carb King a call.

Thanks to pages 43 and 44 of the "1950 Servicing GM Model "B" Carburetors" manual posted by Keith Hardy, I think I know what the hole is for. Evidently, it was drilled to correct a stalling, rough idling or hard starting when hot problem.

Pg 43- http://chevy.tocmp.com/1950carb/50c43.htm

Pg 44- http://chevy.tocmp.com/1950carb/50c44.htm

Consequently, I think I will temporarily plug it and see how it runs. If it does not have any of the hot problems described above, I will install a permanent plug.

Thank you Keith for sharing your manuals with your fellow stovebolt lunatics.