Not many Mercury BP motors around especially up here.
This one is made up of different motors
https://www.kijiji.ca/v-powerboat-motor ... nFlag=trueThe blue decals were on the 140 mercury.
The early BP decals were red.
https://encrypted-tbn0.gstatic.com/imag ... F2bs6X53WtThe shift-able gear case allowed the motor to run in F [FAMILY] class in OPC racing.
It was the weakest part of the motor with a 10 hour life span and had to be sent to mercury for rebuilding.
Two ratios 1:50 and 1:75......1:75 I think was best.
Those of us who were lucky enough to get a new one had few problems with the powerhead other than the rev limiter and the differences in porting block to block. The rev limiter was 6800......easy to by pass .....some engines would barely turn 7000 while others would run 7500.....it all depended on the engine you got.
The adapter plate allows you to mount the speedmaster gear case to the BP mid. Looked cool, but the same speedmaster bolted right on the lighter stock 15 inch mid so most didn't go the BP root due to cost and extra weight.
Those that later mixed different powerheads on BP mids found they didn't usually run as good as the originals. Problem was porting, pistons, crank timing and tuner match to the powerhead.
When the 1250BP studs down came out in 1967.....the big advantages were the way it came out of the hole compared to the stock 15 inch with big 2 blade elephant ear props that wildly shook the motor getting on plane...and the way a V hull drove with little torque on the wheel......plus the noise was wonderful and very racing.
