New To The Jet Boat Scene, Have Questions

[starbuck]

i just purchased a 1974 starbuck custom with an oldsmobile 350 out of a donor car. nothing was complete when i bought the boat. the motor was bolted to the bell housing but it didnt even have motor mounts. first question is do i need a marine water pump? i have a 5/8 hose coming from jet drive and i need help on how to route the cooling system. whats the purpose of water jet manifolds. should i just run plain headers? how can i find out what kind of jet drive i have. the guy told me it was a jacuzzi jet drive. my impeller looks like a propellor almost. it doesnt look like the normal impellers i seen pics of. where the motor sits is like a sealed fiberglass sump and the motor mounts are supposed to mount to the walls but its fiberglass and i cant get to the back side how sould i go about that. i can send pics if it would help. thanks jeff

[Cheap Thrills]

A pic is worth 1000 words . as far as the water pump goes no you wont need another one the jet will supply more than the engine will ever need . there are several excellent threads on plumbing a jetboat you may have to dig a little but they're here .
post pics of your project .
C.T. :wink:

[starbuck]

i will have the pics up asap i just need to get some close up pics

[OMEGA_BUBBLE_JET]

sounds like you might have a jacuzzi jy pump. it is an axial flow pump and the impeller is much different. the impeller is open around the edges and does not have a shoulder around it. it also tappered to match the pitch of the wear ring. You can shim the impeller into the wear ring as the pump begins to wear by installing shims behind the front bearing housing.
Overall the yj is a good ski boat pump but don't expect a rocket ship or a hotrod. You can throw more hp at it but it is really a waste of time. I have a yj jacuzzi in my boat BTW, so I am entitled to slam on them :wink: I have heard mixed opinions about installing the energizer kit which basically converts the pump to a berk. the main complaint I hear is that the intake is so large it feeds too much water to the mixed flow impeller causing high intake pressures and more drag.
the yj does provide superior low speed handling and holeshot for pulling skiers. forget about ever being able to throw a respectable rooster tail with that pump. very few had diverters on them and the ones that do, do not have much up travel past a few degrees. I think my tail maxes out at a whopping 6ft out of the water at WOT.
I am not trying to discourage you from working on this boat I just figured you deserved the truth and the facts up front. I have had my boat for 4 years and have had absolutely no problems with the pump and I enjoy the boat the way it is. Just don't expect to win many races with the yj pump.
Omega

[moneysucker]

Sounds like you may have a 3 point motor mount system where the bell housing is attached to the pump drive. It is not bad . The water jet exaust will be good. You can hear your stereo and no header burns.

[Challenged Pimp]

I also have a Jacuzzi YJ in my ride. I was beginning to think it was total garbage, but playing with it recently gave me a lil hope (just little) :D
It does have the energizer kit, which looks like an Agressor bowl, and has a divertor. It ran 43 MPH with the bone stock 460, and last week I installed a droop and 4 degree wedge and picked up to 48.3 MPH. This is also like a 260 HP piece of crap smog headed 460, so I think with a lil head swap and some extras I can pick up quite a bit. Keep in mind this boat is a 21' slug, I hear the boat probably wouldn't do anymore than like 38 MPH with the stock Jacuzzi without the energizer kit.
So I guess the energizer kit does do a lil something, only downfall is the turning radius. Without the droop, it sucked royally. Seriously it took like an entire lake to make a u-turn, and this is with a rudder. Installing the droop helped alot, but still isn't very exciting. But hey atleast it throws a half way descent roost! :D
http://www.***boat.com/image_center/data/520/1688Roost.jpg
Here's what my pump looks like now (if it helps any)
http://www.***boat.com/image_center/data/500/1688Pump.jpg
Also if you have 3 point mounts, the rear mount bolts onto the actual pump housing. Mine had Chevy 3 point mounts when I bought it and that's how it was setup. I assume it's probably the same. When I changed over to Ford mounts, I had to cut the floor open so I could get to the back side of the bolts. So you may have to do that as well. I wanted to inspect the floor anyways, so it wasn't a big deal for me. This is what I did before getting the mounts out...
http://www.***boat.com/image_center/data/520/1688Mounts.jpg
And you don't need a water pump, just water pump cover plate that you run water to from the pump. Looks like this....
http://www.rexmar.com/images/page167.jpg

[starbuck]

i have finally got the pics. tell me what you all think.

[Frosty_pop]

Looks like a Jacuzzi YJ pump
as for a water pump..... the jet drive is your water pump. All you need is a water bypass that hooks to the water pump fittings.