brian41

iTrader: (1)

Looking at B&M 250's will they work on these motors without any mods and if so what boost.
502 cid with stock JE 8.75 pistons
Crane roller cam custom grind
Lift [email protected]
In. .598 232
Ex. .632 244
112 lobe separation
Heads have been match ported with some bowl work and have Manley severe duty intake and inconel exhaust valves
Thanks Brian

Lmarth

Brian-- The B&M 250 Blower is standard on the Mercruiser 600SC and 800SC. It's a 420 Cubic inch blower making 6# boost on the 600SC and 8# boost on the 800SC. It does this through the Supercharger Gear Ratio (Pulleys). It's .93:1 on the 600SC (502) and 1:17:1 on the 800SC (572). It'll bolt right up. Obviously the carb jetting,etc. will have to be set up for your motor. Your compression ratio is higher than the 7.5:1 that's used on the 600SC/800SC. The B&M 250 does not have an intercooler with those two motors. I'm not an expert on this, but you could probably get away with 8.75:1 as long as you didn't get carried away with ignition timing. If you get serious on this, I'd suggest calling someone like the folks at the Blower Shop for their recommendations. Just trying to help.--Lou

TomFTM

iTrader: (3)

Brian, You can run the bm 250 on those motors, You can run a single dominator or 2 750's. The twin carbs will give you better fuel distribution(sp) and a little more power than the single dominator. You can safely run 5 psi of boost with no innercooler as long as you run 93 octane .

The 420 mega blower is the blower used on the 600 and 800 sc not the 250.

Tom

Lmarth

TomFTM-- Thanks for the clarification. I obviously got the two blowers mixed up!

TomFTM

iTrader: (3)

Lmarth, No problem . Tom

brian41

iTrader: (1)

Well I was the winning bidder on ebay tonight on a set of B&M 250 blowers with carbs, linkage and flame arrestors so here we go hope all works out. I spent about $50,000 3 years ago putting together current package and gained about 15 mph so this is cheap so far.
Thanks Brian