Jon G is correct, Here is a lengthy explanation but, this will cure the malady that makes so many hate the Rochester model "B". Yup, your going to have to take the carb. completely off. Take the air horn off (4 thick headed screws), put a flat steel measure on both the bottom side and the bowl if either one shows warping salvage screws and remove all parts and toss the two pieces in a bucket. Buy a good rebuilt carburetor from a real carb. re-builder, check with carbking above. If the horn and bowl are good proceed as follows; pull up the accelerator pump, if it has a blue cup and a flat bar with a slot you have a BV, however and this is where it gets weird it can have a round shaft and blue plastic OR leather cup. I personally prefer leather but, it's not about me, long story for later. This is extremely important and the main reason so very many dislike the Rochester model "B". Once you remove the accelerator spring (a very light about 1.6 inch long spring), inspect the bottom to see if there is abnormal wear like a high spot wear, lightly sand and set aside. NOW & THIS IS CRITICAL look in the accelerator well, and at about 10:00 (carb front pointing to the left), at about 10:00 will be a hole at the bottom of the well. This is where the problem with model "B's is, at about 4:00 will be what many think is a second hole but it's only a dimple or it may be a hole, the dimple is a undrilled cast. You will have to have a very bright light and a long needle bent at a 90 degree angle or a dental pick. If there is no hole but the well has two balls (smaller than a BB), if there is one hole and two balls that causes idle problems the proper ball is aluminum. The rebuild kit has three balls two steel and one aluminum, one steel ball is for the metering jet and the other (same size) is for the accelerator pump well that has two holes. justhorsenround put the un-needed steel ball into your storage drawer in a bit of grease. Depending on altitude a #58 metering jet should work just fine for a BV. No instructions with any rebuild kit will explain this and some just instruct to put both balls in well??????????? Precisely set the float and check to make sure the brass bladder does not touch the bowl walls or have a major dent or crack,hole in float. Touching the wall will also cause the problem your friend is having. Simple carburetor that can cause major problems. DO NOT overtighten four screws on air horn, will cause warping. Check all the small holes on bowl bottom and throttle body, sometimes may have to drill extra hole in gasket. Doc
Last edited by Doc.Hall; 06/12/2020 10:47 AM. Reason: grammer
