b&m 250 blower upper pulley.
 

Been out of the loop for a bit. I built a new motor for my 89 warlock euro24 last winter. This is what I built. Its a 516 bbc with a b&m 250 blower, grumpy jenkins 345cc heads, nickerson dominator, msd ignition, rm builder did the hyd. roller cam in it, I used the factory crank, oliver rods and srp pistons, etc...it came out real nice but the boost is a little lower than I expected. Currently the upper pulley is a 3.66" pulley and max boost I have seen is 4.1 pounds at WOT (6200rpm). I'm a bit under proped with the bblades bravo1 24p that's on it. I've tried a factory labbed bravo1 28p and it brought my rpm's down to 5700 so I'm thinking a 26p bravo is where I'm going to need to end up to get my rpm's where they need to be. If it helps, the boat runs 83mph with the 24p and 86mph with the 28p. Ive read that b&m makes a 3" pulley and a 3.25" pulley. Which of the two do you guys suggest to reach 5-5.5 pounds of boost.

Weiand Part#'s
155191 = 2.75"
155192 = 3.00"
155193 = 3.25"
155194 = 3.65"

What rpm are you looking to end up at? Remember that upping the boost will up your rpms with the 28. I agree with the 3" pulley but would think the 28 might be the one you'll end up in.

Main thing is what size lower pulley are you running right now?? If your running the 5.40'' lower pulley, you are 50% overdriven right now. Going to a 3.25'', youll be 66% over. 3'' will be 80% over.

When I ran the 250's, My little 468's at 66% over, made 5lbs. 80% over, gave me 7lbs. 50% over was about 3lbs. So each pulley change was about 2lbs. I'd try the 3.25.

My guess is the 3'' pulley will put you between 7-8lbs.

Here is a link to the instruction book with good info on CID and boost.

https://dl.dropbox.com/u/42339868/25...directions.pdf

Would like to end up in the 5800-6000 range. The cam was designed to run up to 5800 by Bob M. I don't have a problem with it spinning 6k though. Its making power there still. You can really feel a difference though between the 24p and 28p when it comes to getting the boat on plane and in the mid range.

You bring up a great point M/T......and I'm glad that you did! I switched out the lower pulley from my 250 for one from a 420 set up. I liked the 6 bolt mounting pattern and style much better than the 3 bolt 250 set up. What comes to mind now is that the 420 lower pulley is slightly smaller than the 250 lower pulley I was originally going to use.....not by much but is in fact smaller. I want to say 1/16". Anyway, with the smaller lower pulley the upper pulley is turning slower now as well.