Thread:

Newbe Questions

im not going to be much help but nice boat. 7000 rpm that thing is going to need to push some huge #'s. that thing is going to be a wicked motor cant wait to see the pics. if theres not much done to the pump i think you would want focus on that

Originally Posted by customsandrods

Wanted to add a pic of the pump to get help identifying it and see if they even make a droop for it, I think its a 12JC, let me know if you know...
Thanks George

Geeezuz......can you plant seeds with that too? or is it limited to just plowing

Congrats on the new float...

Looks like you've got a Berkeley JC pump. It's a decent starting point. you can run a place diverter (or trim, which you have) but in order to add a droop or straight snoot you'll need to change out the bowl to a split bowl, where the nozzle unbolts from the bowl.

Before you even start thinking about that motor...do your research. I don't know a lot about hulls, but I do know that most of the older shallow V bottoms get kinda sketchy above about 85mph.

You don't need to spin that pump to 7000.

Here's a link to Duane's impeller cut/horsepower chart. Not 100% accurate due to a bunch of other variables...but it's a pretty good idea.

http://hi-techperformance.com/images...r%20Curves.jpg

most pumps come stock with an "A" impeller. If you want 7000rpms, you'd better make about 1100hp.

The first thing you should do is go over the hull itself. Make sure the stringers and floor are solid and there's no rot...take care of anything that needs work.

Then dive into the pump. A loader (scoop) will be of benefit at higher speeds. The condition of the impeller/wear ring is most important though...there are tons of threads in here on pump work/maintanence. Search and read up.

Welcome to rehab.....and congrats on the new addiction!

Rethink your engine. My BBC is roughly 625 HP, and spins an "A" impeller to 5800 RPM, at 86 MPH. (79' Miller hull)

I also had a stock JC pump at first. I modified it with a JG 2 piece bowl, a droop, and a diverter (as well as having the pump gone through and replacing the impeller with a stainless). Then had the intake re-set and added a very basic shoe (the "scoop" you mention) and ride plate.
I also added a loader to the intake.
If I did it again, on different boat. I would not do it all at once. I can't say what addition was the best, because I did it all at once. (The diverter and 2 piece bowl would be the best bet though)
I would start with the 2 piece bowl and diverter. Then perhaps the droop snoot. If I then saw any cavitation I would add the loader. If I wanted to improve from there, I would then add the shoe and plate.

I know nothing about your hull though, and that is just the general order I would do it.

Jet pumps are different than a propeller.
They can only absorb so much HP.
The pump does not care if the boat is moving or tied to the dock. It does the same thing regardless.

Build an engine that can run for extended periods of time, and live comfortably at 5000 - 5500 RPM or so, while making 550-650 HP and you will achieve your goals if the pump is working efficiently. (and the hull is capable)
Concentrate on oil control, and build it for endurance, while keeping it under 6000 RPM.

Several members on here have big inch Ford motors that produce incredible results at lower RPM's than 7000.

BTW, when I bought the boat it was much slower than yours with a crap "re-builder" 454. I don't think it went 45 MPH.
After building the engine, it went exactly 70 MPH. After the pump mods it did 86.

Originally Posted by thatguy

Welcome to rehab.....and congrats on the new addiction!

Rethink your engine. My BBC is roughly 625 HP, and spins an "A" impeller to 5800 RPM, at 86 MPH. (79' Miller hull)

86 with an IMpellor
and
105 with a PROpellor

Originally Posted by Sold honda.bought hondo

86 with an IMpellor
and
105 with a PROpellor

LMAO

Wikus

Originally Posted by Sold honda.bought hondo

86 with an IMpellor
and
105 with a PROpellor

Well, I do own both......and NEITHER is pink.

Just sayin'.......

Since you own/build engines, you'll understand me when I say, build the big roller deal as a "spare bullet", and leave the existing engine alone. When the "killer" is ready, stick the original under a bench somewhere for use when the roller spits out a part or two.....That way, you can still be on the water enjoying your jetboat.....I too, build engines, and I will say without a doubt, a jet boat is the toughest thing you can ask an engine to do. Vehicles sorta coast after a cruising speed is reached, feather the gas, and maintain the same speed. Not so with a boat, and especially a jet boat. Back off just a little and you're going to slow down, so the engine is under a constant load/RPM condition and depends on the boat "drying out" to relax a little.....Been there, done that......Vehicles hook to the ground, jetboats hook to nothing, and as such, 75%+ of boat performance will be found in a very expensive modified pump.....Engines are cheap, compared to pumps........Ray

Your Sunkisst is the heavy lay up as proved by the pic of the guy walking on the deck. On my Kisst you cant even lean on the deck, very light lay up. Your hull would be safe up to around 75-80 without professinal set up and make a great lake boat.