The later Rochester B, BC, BV carburetors used a replaceable cup. In rare cases the carburetor may have a pump with a round stem and a leather cup. These accelerator pumps do not have a replaceable cup and you will need the complete accelerator pump. As shown in the photo, the old pump on the left has a round shaft with a leather cup. Replace the left pump with the accelerator pump on the right . To be 100% sure measure the length of your old pump from the top of the stem to the bottom of the leather cup. That should match the newer replacement pump (2 7/16″)
The Rochester 1 barrel carburetor used 2 styles of accelerator pumps through the years. One has a flat shaft and the other has a round shaft.
Polish the pump well with 2000 grid or finer sand paper, or polishing cloth. You want the pump to have a smooth glide. Apply a few drops of oil to the cup before installing. That along with the gas will cause the cup to swell up. This will take a few miles of driving. Once the cup is wet don’t let it dry out as that will ruin the pump.
#33 is a retainer 90-36 that goes on top of the spring, then the lever #30 85-123 is inserted into the slot at the top of the accelerator pump.
If your carburetor uses a check ball at the bottom of the accelerator pump well, then use the smaller aluminum check ball.
When we refer to the size of this pump we are talking about the overall length. AP327 – 2.851. AP462 – 2.776
Our premium kit PK110 includes the replaceable cup for this type of accelerator pump and the cup works for both round shaft pumps.
This pump uses a return spring 66-15. and a delayer spring 66-44
Illustrates the different in return & delayer springs on the 2 types of Rochester B carburetors.
A – Return spring on all Rochester B carburetors. The return spring goes under the accelerator pump. This helps return the accelerator pump to the top position. 66-15
B – Delayer spring on the round accelerator pump stem (late) type of carburetor. The delayer spring goes over the pump stem. A retainer then goes over the stem. 66-44
C – Delayer spring on the flat accelerator pump stem (early) type of carburetor. The delayer spring goes over the pump stem. A retainer then goes over the stem. 67-3