Couple of 250 B&M Blower ?'s
 

I have a 250 B&M Blower atop a 509. Couple questions, one stock pulley what should the boost be? Im running about 3.5 4 psi i believe. 2. Should i run a smaller pulley? is it worth it and would it pose any interanal problems. 3. I see that there is a vent in the front of the blower snout, its pushing out oil? anyway to stop this and what causes it? Thanks all for the input and thanks to everyone with the help on the carbs it rain pissa sunday, ran a 79.2 on the gps with no air grates to force the air in the engine bay hopefully with those and a little more tuning ill break mid 80's and be happy there
Mike

Historically that particular blower's bearings are a little undersized and should be replaced. Since the bearings are small they tend to wear out quickly. When they do the rotors will start to bang together and the shavings will erode your rings etc. A rebuild alone may significantly improve your performance. New teflon strips will pack more air.

Thanks menace looks like ill be talking to the blower shop.
- Mike

The plugs in the top oil fill have a hole in them replace the plug with a unvented one. What size pulley is on the blower the smaller spins it faster and the more heet it builds so more boost doesen't always make more power.

FS its the stock blower pulley, true about the pulley didnt think of it that way about makeing the more heat so ill have to keep that in mind. So i should just get a new venting plug because mine is clogged?? is that what you mean

DITTO
I melted mine down in '04, sent it to the Blower Shop for the rebuild. The only thing original on it now is the case! :D

Thanks Liquide i will have to hit the blower shop up. do they have a heavy duty bearing for that or heavy duty setup?
Mike

:drink:

So metal i will see internal problems? danm

1) There really isn't a "stock" pulley. You change the blower pulley to change boost. Smaller = more boost.
2) The amount of boost you can run depends on how the engine was built, compression, cam, heads, ignition advance etc. and the octane rating of the fuel. If you dont know about this stuff, dont screw around with it. You could melt a piston.
3) There is a vent/plug. If it's pushing oil out, your blower seals may be going bad pushing gas/air into the front lube reservoir. I would suck out all the gear lube in the resroirs (probably contaminated with gas) and replace with new gear lube. Then watch and see if it starts overfilling quickly.

On my deal they enlarged the area around the gear set and installed their gear set and bearings which were a good deal larger than the factory stuff.

RD i know about it but know a complete genuise on it only because ive run natruarlly asperated motors and they have all be small block. This whole blown big block thing is new to me. The last owner actually melted a piston thats why its a 509 and not a 502. The motor was built for reliability and i talked to the guy who build it (JB Auto and Machine out of MD) he said with out a problem it would handle the boost just have to watch the timing on it.
Liquid if you dont mind me asking what did the rebuild run you?? Also RD thanks for the info i will suck it out i mean i have to change it anyway and check it what should i run for oil in the lube chamber??
Thanks
Mike

inter-anal :rolleyes:

Sick Stinger, the rebuild was about $1600 in Sept. '04. I had been turning 8-9lbs before the melt-down, so after the rebuild I stepped up the pulley size and got the boost down to 3.5-4lbs. I gave up about 8 MPH in doing so, but hopefully it will stay together for a while now.

Liquide do you still have the other blower pulley???