12JB-B

[LeadFootTheRabbit]

I'm putting together this old boat I bought a while back. The pump is a berk 12JB-B and the motor is a SBC. I can't find any info on this pump. Can anyone help me out here?
Thanks LDFTRBT

[Jetmugg]

Good News, that's a pretty good pump. Berkeley is definitely one of the preferred pumps in terms of parts availability and performance potential. The model 12JB should have a split bowl, which is a good thing. This means that you can use bolt-on accessories such as drop snoots or wedges in order to tune the ride and attitude of the boat. The -B extension indicates that the pump is (or was originally) equipped with a B cut impeller, which is well suited to use with a small block engine. The big block engines generally came with A cut impellers. The B impeller will allow the smaller engine to turn more rpm's, allowing it to get closer to it's power peak. There is a wealth of information available here, and at some other jet boat related sites on the net.
SteveM.

[Bense468]

I always thought that the JB was an older version of the JG. I am sure there may be a little change between the 2 but my pops always told me that the JB was a good pump. He worked with Berkeley and ran that same exact pump in his sanger hydro that put out some good numbers. It is in fact split bowl.

[SoggyJet]

The JB pump is an earlier version of the JG. The bowl on the JB is not as efficient as the JG so if you want to upgrade, you stand to gain performance by going to a newer bowl.
Doug

[LeadFootTheRabbit]

Hey Fellars, thanks for the information. Heres another question... With a stock pump(12JB-B) and a SBC, what kind of RPMs will I have to turn to make this pump work. LDFTRBT

[Bense468]

I would guess and I am just guessing 6 or 6500 with a small block. A small block chevy should handle that. I spun a lot more then that in my 67 camaro

[SoggyJet]

LDFTRBT
Find an RPM vs HP chart for your impeller. Plot the HP from your SBC on the chart and find the first point on the chart where your SBC HP is less than what the chart says you need. This will be your maximum RPM.
This requires that you know the HP throughout the RPM band of your engine. For instance, if your engine has 330 HP at 4000 RPM and the chart says you need 350 HP to turn 4000, you have hit a limit and you will not rev any higher. Even if you can make 450 HP at 5500 RPM you will never get there because you hit the barrier at 4000.
If you need more revs to get into your horsepower band then you need to cut the impeller smaller or build more HP at the point you need it.
Run it and see what it does.
Good luck, Doug