The Stovebolt Site Forums The Shop Area Engine Shop Yet Another Carb Question

Okay, a while back I asked for some info on the venerable Rochester B carb on my 1966 C10 250/powerglide. I've had it with this carb, rebuilding doesn't help it, and I've read nothing positive on this board regarding this carb other than they make great doorstops, etc.

This brings me to the question of what carb to replace it with. I'm looking for something I can tune and forget about it. The truck is mostly used as a commuter and is my daily driver. I'm looking for something relatively a 'drop-in' fit and rememeber I do have an automatic, so I need provisions for the kickdown rod to the tranny. From the searching I've done, the Carter YF carb will fit but I'm not sure if that will interface with the tranny? Any other ideas/suggestions? The one barrel Holley setup that was just posted looked good, but then I've found that a lot of people on this board don't like Holley carb's either.

Thanks in advance
Isaac

Carter YF #4376s was original equipment on a 1967 Chevrolet truck 250 CID and A/T.

Jon.

Thanks carbking!

If you don't want the rodchester you can mail it to me!

I have a 216 and two 235's all running more or less. All three have the Rochester carbs and all three carbs have been in service on my 48 daily driver and all worked fine despite being parked for over 20 years. I have to wonder what is so bad about the B carbs. On my stock engines, they all start, idle and run out well. I even had a couple of B's that were in a bucket in the back of my 48 when I bought it and they also work. They seem pretty tough to me. Maybe I just dont know what a good carb should be like. I need to go drive my buddies GMC that is Carter equiped and see what I have been missing.
Ralph

I think the problems with B's come about when people try to rebuild them and overtighten the air horn screws, distorting the gasket surface. Another problem is that not many people really understand how the power valve system works and damage it or don't get it properly rebuilt. A problem I've had with mine is that the float bouyancy tends to be iffy (the floats are really small) and the carb floods with the most miniscule speck of debris or overpressure from the fuel pump. They also tend to be really sensitive to float adjustment. Other than that mine works pretty well, the auto choke works (it's off a '66 250), the idle and mixture is pretty consistant, and the thing never ices or plugs up. I always get about 15 mpg in the city and I can burn the cheapest unleaded gas I can find.

A properly restored Rochester B will work fairly well, and will do so for a few years. The problem lies in the cost of restoration.

The major area of concern is the lack of airhorn to bowl screws (4). As there is too much distance (or too thin a casting) between screws, the airhorn will, in time, warp. The zinc alloy becomes malleable (sp) during heating/cooling cycles, and the pressure causes the warpage. As the vacuum passage controlling the power circuit must be sealed at the mating surfaces, this warpage causes an internal vacuum leak at the power circuit causing the power circuit to always be on. To eliminate the warpage, the restorer must use heat and pressure to form the casting back to trueness.

The Rochester B is not the only carb to suffer from too few screws. Carter's first W-1 (1932 Chevrolet) had a similiar problem. However, Carter acknowledged the problem changing from 4 to 5 screws after 2 years, and from 5 to 7 screws after3 more years. The Stromberg model 97 also had this problem, but when Stromberg changed from the E series to the A series carburetor (after 3 years) the problem was corrected. The Rochester B went from 1950 to 1966 without correcting this problem.

Contrast that with other Rochester products. The first Rochester 2-barrel was the AA series of 1949. This series was modified in 1950, and scrapped in 1951 in favor of the BB (a two-barrel version of the B). The BB lasted 1 year!!!!! and was scrapped in favor of the G series (one of the finest 2 barrel carbs ever made!).

Also, as Josiah mentioned, the float buoyancy is marginal.

The B can be made to work, but the Carter is just much easier to make to work; and the Carter also is much easier to modify if the engine is modified. The biggest problem with the Carter YF is the diaphragm type accelerator pump. These can give problems in vehicles which are rarely started.

Jon.

My rochester works fine (56 3200). After I bought it, the accelerator pump went bad and it would only stay running if you held the gas pedal down. After I rebuild it with a NAPA kit it's fine. It seems easy to adjust and keep running. I haven't had problems since. The rebuild was over two years ago.