Looking at a Jetboat, What to look for?

[Maddog_merc]

I am looking at a Jetboat and honestly don't know what I am looking at or what to look for.

The motor is a 455 Olds sounds good and has good oil pressure and I am not really worried about it but I don't know nothing much about Jetdrives.

The boat is about 16'+ and has the driver on the left side like a car, I haven't had a chance to get a make or year on the boat but it has a Berkley jet (without the nozzel for the roost :confused: , it is not a low profile style so I figure it will be a real slug on the water. Any tips about what to look out for? or stay away from?

[halveb]

The Olds 455 motors were used a lot in the old jetboats. They were good motors but were usually more expensive to build than a Chevy. Mondello is a good resource for Olds parts and performance equipment. The first thing to consider is do you want an Olds.

The next thing to consider is in what condition is the jet in. Jets are pretty simple. There is a wear ring on the inside of the bowl and an impeller attached to the drive shaft. The more wear there is on the ring the more slippage the jet will have. It isn't too difficult to install a new wear ring and rebuild the jet and a complete kit is about $400.

Make sure the motor is in good shape all the usual things, compression or better yet leak down test. You can usually gain the most out of a jet by working the pump rather than the motor anyway. Once you have the pump as efficient as possible then start building the motor. A stock 455 with 350hp will usually push a decent hull around 55mph. Anything more than that will require more horsepower or a more modern hull (circa 1990 or more recent).

Jack McClure of MPD out in California is well respected pump builder his number is (949) 631-2040. I haven't had my jet back together for a few years go a gofast outboard and have been playing with that so I'm kind of out of touch.

[swampman]

hope ya bought the boat...i run a modified olds in a 76 22 ft sleekcraft with a cuzzi y pump..i get an honest 72 on the gps with full fuel and one person...(me)...the olds is strong but expensive and parts are not as readily available as the rats...if it doesnt have an edelbrock torker and a holley double pumper...put em on...cp has cut impellers for me as well as north american marine jet...both have done me well...like the fine advice given you earlier...tune the pump to the motor...and dont give it the gas near the beach to impress the chickies...the money you spend on the pump is better spent on her....hang loose...swampman

[Fivetoez]

Maddog - Did you buy the boat? I...like yourself didn't know what to buy and went for a jet drive boat. It is my first boat and I am loving it. I spend at least 4 out of 7 days a week on the river by my house and noticed that with OB's folks are always replacing the prop. I have a merc cruiser, V6 with EFI. It's 240 hp. The boat is 16 1/2 feet and goes 70 mph. I know that doesn't seem very fast compared to a lot of the boats listed here but I have a blast!

[MADDOG355]

This is maddog_merc

(I was having trouble with my other ID)

I did not buy that boat but I did buy a 74 19' Caravell with a 455 olds and a jacuzzy YJ (I think) pump I am looking at spending about 1500-2000 on the pump and and still have to replace the motor as well (I have a line on a good used 455 from a car) But I only paid 500 for the boat so I won't have too much in the whole outfit.

I am going to start a new thread about the boat and try to post a pic as well.

[mmiller40]

free bump...I just posted about a 72 sleekcraft with a 455 olds... All information is appreciated :)

[Steven]

people complain about the olds not returning the oil from the heads back to the pan fast enough and burning up the motor. of course, they get out there and stay on it too much i guess. im sure that could be fixed if it was a problem, but i've heard of this more than once. :confused:

[CheckMerc]

Im not a jet boat guy but am an Oldsmobile racer. For good info on building your Olds Stay away from Mondello and go to www.Realoldspower.com (http://www.Realoldspower.com) or www.rocketracingandperformance.com (http://www.rocketracingandperformance.com) or www.btrperformance.com (http://www.btrperformance.com) or www.oldsmobileperformanceparts.com (http://www.oldsmobileperformanceparts.com) The last three are shops that specialize in Oldsmobiles with out the high mark up like $Mondollar$ the first is a Forum. hope this helps. Andy

[Maddog_merc]

Well after a short leave and a few boat deals I am back on the water (somewhat). This time with a 74 howard 19' 455 Olds with a Berk JB pump and A (I think) Impeller. Right now I am waiting for the crank to be turned. Going to run a stock motor this season and buld a motor over the winter. I am going to stay with Olds power I think, One of the local guys is suposed to be running in the 70's (gps) with a Olds so I think I will be satisfied with a good build for now. Any sugestions on parts and were to get them?

[nitrousdog]

Its all acording whether you want do go fast or make a bunch of noise. Olds have there limitations. Big block Chevy's and Fords don't. Try to get a blower for an Olds and you will find out. Cam selections are poor too. You want a dominator, berkeley or am turbine pump.

Nitrousdog

[Maddog_merc]

I know the olds has it's limits, but I think it can meet my needs. I figure if I can run 70 or so I will be happy. Hope I don't need a blower for that, but have thought about a paxton ;)

[nitrousdog]

Put a blower on a olds and you will blow the rods right the bottom. Olds have week bottom ends. Yank the Olds out and put a BBC in. My motor is 800HP and turns 7 grand. Been running the same motor for 5 years.

Nitrousdog

[rockdamage]

one that floats

[JerseyClown]

My motor is 800HP and turns 7 grand. Been running the same motor for 5 years.

Nitrousdog

I REALLY like your motor..... 7 g's...nice....