anyone familiar with the pulley's on the 420's? a friend just wound up with one he is putting on a 468 BBC with oval port heads and around 9:1 compression and it did not come with the crank pulley. the blower pulley is 5.8" 16 rib and he needs a crank pulley that would put it around 3 or 4 lbs of boost. seems there are only 4 crank pulleys available. anyone have running this blower that knows what to start with on the crank? motor is going in a street car mostly for show and to ensure an adequate amount of rubber is put down to protect the roads.

I would just change it over to 8mm pulleys. they would also look alot better on a street car

https://goodvibesracing.com/Ratio_Charts.htm

I think I have a B&M catalog that has a pulley chart. I'll see if I can scan and post it. I also think I have some 16 rib pulleys. I'll take a look.

thanks Mark, ever since Holley bought out B&M it is hard to find any info. if all else fails he could switch to 8mm pulleys but tying to work with what he has.

I found the catalog (page attached) but no pulleys.

thanks Mark, that is what I needed. good news is it looks like they found the lower pulley so now we can figure out what it will do or what we need to find.

Id prob start with this 5.25" lower pulley. With the 5.8 upper, that will be about 10% underdrive. Then, when he wants to run some race gas, flip the pulleys around, and probably have around 10-12psi (10% overdrive)

https://teaguecustommarine.com/em001...-16-rib-pulley

Did you by any chance find a top pulley for the B&M 250 blower 16 rib top pulley splined? Do you have any ideas on where to look for this pulley? Thanks for any help you can provide.

What dia are you looking for?
I have some pairs in the shop

I have part numbers if that will help. B&M part numbers 2.5 inch 155190 and the 2.75 inch is 155191.