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Thread: New to jetboats - hi all

  1. #1
    Snorider
    Hi, just bought a jetboat and love the forums! Seems like there is a lot of useful info here!
    Here is what i bought:
    1978 Sleekcraft Kaui (i think thats how you spell it)
    460 Ford Packajet, 12JC-A pump w/ jetovator
    Currently, it will do 62mph @ 5400 - 5500rpm
    Seems like someone did some work to the motor, but not really sure. After reading the forum topics about the oil problems with the 460's, it kinda made me wonder about whether it was healthy for me to beat the boat that hard
    Got it about 5 days ago, and i have been running it at WOT for about 10minutes nonstop each time i took it out - and so far, there havent been any problems. The guy i bought it from was running 20w50 synth., so thats a good thing.
    And the fact that the water temp of the lake is a brisk 45F, that is prolly helping to keep it cool.
    The thing has plenty of oil pressure, (80+ lbs @ wot) - so much that it will slowly seep out of the PCV valve - which makes me tend to believe what you guys say about the oil stayin in the heads.
    Since it still has the points / condenser distributor on it, i am probably gonna switch it to HEI - any recommendations? I was thinking MSD.
    Also, is switching to a 12-JI worth it? will i notice a speed increase? Just like everyone else, i want 70+mph
    It doesnt have a place diverter (since its a JC model), and i dont know what impeller is in it.
    [ May 04, 2003, 09:39 PM: Message edited by: Snorider ]

  2. #2
    HBjet
    Snorider:
    Currently, it will do 62mph @ 5400 - 5500rpmWelcome to the boards!
    First thing I would check is either your pump, or your RPM gauge. If you have an A impeller, I would say your in need of a pump rebuild because that RPM is really high. And did you GPS the boat, or do you have an MPH gauge too? I only ask because that MPH might not be right if you didn't use a GPS.
    I would have your pump checked out before you decide on replacing it. A basic rebuild may be all you need.
    HBjet

  3. #3
    HammerDown
    Welcome to the Maddness...I agree with HB said...I would look to see what size Impeller you have, with those rpm's you should be going faster...GPS is the best way to tell that, if its a smaller cut (B)or (C) and the pumps tight I'd up to a larger size. However if the pumps loose and there's a full (A) in there, just do a rebuid. The Impeller is usually stamped with the Impeller cut. HOWEVER that may not mean it wasent already trimed down.
    Where at in Pa. you from? I'm in the Plilly area, or just south of the city.
    PS. there's a great Book by Seloc Publications titled "Marine Jet Drives". It's all in there.
    [ May 05, 2003, 06:33 AM: Message edited by: HammerDown ]

  4. #4
    Snorider
    The guy i bought it from just rebuilt the drive (or at least he said he did), and gave me about 6 gaskets for the drive as well. I used the in-boat speedo to get 62mph, but I would guess that the boat is doing anywhere betwen 58-62 on GPS judging by how it runs against other boats.
    Is there any way to see what the impeller is without taking the bowl out?
    Again, thanks for all the great info!
    The guy i bought it from told me it has cobrajet heads on it, i was planning on looking for a casting number today, just to verify. From what ive heard, they are decent heads to have though.

  5. #5
    Snorider
    HammerDown:
    Where at in Pa. you from? I'm in the Plilly area, or just south of the city.
    Northeast - up near Stroudsburg and such. If you look at a map, im on lake wallenpaupack; I think its the largest manmade lake in PA???

  6. #6
    Ranz1
    Welcome Snorider, This board is GREAT for info and parts. I have only owned my CVX20 for about year and a half and i have leard soooo much about jets ,engines, carbs, hulls, ect. People help if you if you need a parts that they got. I plan on hitting Lake Wallenpaupack this year. Will hook up. I boat in Swinging Bridge Resevere, in Monticello. You should come out ther some time. Also that book that Hammerdown talked about is great... Anthony

  7. #7
    HammerDown
    Snorider:
    The guy i bought it from just rebuilt the drive (or at least he said he did),
    Is there any way to see what the impeller is without taking the bowl out?
    Impellers are stamped on the back side(bowl must come off)...how about contacting the seller and asking him...If he rebuilt the pump, he should know.

  8. #8
    Snorider
    I tried that already - i asked the previous owner and he didnt know. He was able to tell me that it was the stock impeller, so whatever came with a 460pacakjet is what i got, most likely a B or C.
    I should probably upgrade to a stainless impeller, considering right now its turning 5400rpm and the previous owner estimated the motor at 425hp.

  9. #9
    Hotcrusader76
    Welcome aboard! This is the next best adventure to joining the military.
    ~Ty

  10. #10
    Bense468
    Something is not right there. I would definatly look into it. You should be getting more speed out of that kind of rpm. The numbers are just not working out. My guess would be that you are running a "b" or a "bc" if the pump was just re-built. If it is an A the guy is stroking you and it needs re-built.

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