Rochester B, BC, BV Power System

Power Piston

Power Piston – Removal, Installation & How it Works:

Rochester B Carburetor

Rochester 1 Barrel Frozen Power Piston – How To Remove

When a 1 barrel carburetor sits for any length of time (years), the power piston will most likely end up frozen in the carburetor. Penetration oil probably won’t get it out, but heat will.
Clamp the carburetor in a vise, apply heat to the ouside of the power piston well. As you heat gently wiggle the power piston. Once you get the carburetor hot enough, the piston will start to move and you should them be able to pull it out.
Buff the power piston which is brass to get the dirt and grime off. Polish the inside of the piston well with crocus cloth. You can also use silicon spray lubricant and a brush to clean the well. The point here is that the power piston should move in and out freely. Only vacuum pulls the piston in.
Rochester B Carburetor

2 Stage Power Valve (on some)

Rochester B 2 Stage Power Valve

The two-step power system provides better fuel distribution at the top end of the cruising range where slight enrichment is normally required. It performs this function by the use of a new type power valve assembly. Looking at the illustration, note that the power ball slightly off of its seat, (as it will normally be at the upper end of the vehicles cruising speed), the clearance between the ball and the power valve well is very little and actually controls and meters the power fuel flow. However, at wide open throttle, when full enrichment is required, the ball is moved out and past the restricted well area, at which time the regular power restrictions, pressed into the well support assembly, controls the power fuel requirements. This power valve assembly uses a barrel shaped spring to provide clearance for the spring within the lower well.

Updated on 08/30/2021

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