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Thread: 22 classic introduction and prop question

  1. #1
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    22 classic introduction and prop question

    Hello all, this is my first post and introduction since I bought my boat about 2 years ago. It is great having this forum to reference from.

    It is a 1990 with the 460 and KC since I bought it I have rebuilt the drive and purchased a spare in case the inevitable happens.

    Now that I have that taken care of, I am building my engine up.

    so far.
    Closed cooling, 552 stroker, edelbrock heads(original exh port location) long tube double wall headers (304 stainless made at my house) and of course the usual cam and 850 CFL carb, etc...

    my plan is to keep the revs around 5000 to keep parts together, is it really true that rpm kills out drives or is it just power in general? No, I don't water ski and gun it out of the hole.

    As for planning my prop do you have any suggestions? I was thinking something around a 26-27 prop? I should be making somewhere around 600-650hp, but that is only a guess. Do one brands work better than others?

    hopefully the attachments come through.
    Attached Images Attached Images

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    Welcome aboard. Torque and heat kill outdrives. I think the KC is a resilient drive. People blame Rpm on the destruction of a drive because at speed the drive is never adequately cooled with out a drive shower. The gear oil has a tendency to burn and loose it shear strength . Aside from blowing it up 650HP through my Alpha would require at least a 30P to keep the RPM under 5000. What is the ratio of your KC?
    machinist ,bore it deeper,ream it bigger, and lap it to a fine finish



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    Thank you for your info, I understand that the KC has a large oil sump in comparison to the bravo so it cools better, but should I work out a drive shower? Does it matter that I am in cold water? Lake Tahoe and the pacific? 50-60ish degrees.

    my ratio I believe to be 1.47

    Is one brand or style of propeller better than another for this boat?

    Thanks again! I'll have more pictures once I get back to work on Monday.

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    Welcome! Folks have had great success with the older Mercury Rev4 props. They come in 27 pitch and tend to run just a touch stiff. If you like what you get with the Rev4 you can always add a little more cup to get more top end out of it but most folks run them bone stock. They have PVS holes also.

    What model and pitch prop did it come with?
    1972 16 OB - C16B-63 - "Surface Tension" Resto Project
    1974 16 OB - DMR16106017-B - "The Mule"

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    I think you'll need 29-30" of pitch

    The Merc Rev 4, four blade is my prop of choice but they only come 25p max stock. Even modified to 27p, I don't think it will be enough to stay close to 5000 rpm at WOT.
    With 600+ HP and big torque from a stroker, my guess is that you'll want to start with a 30" pitch prop. There are guys running modified Bravo 1 props. Personally not my favorite out of the box/stock, but I've had good luck when modified for more bow lift.
    Hydro, Power Tech, and Turbo do make other neutral lift 4 blade props.
    I really like the Hydro P5X 5 blade but they are pricey.
    Thank you, Patrick
    1994 18' Classic 350Mag Alpha

    Previously owned Donzis -
    1996 22' Classic, 502Mag Bravo
    1987 20' Minx, 350Mag Alpha
    1975 18' Classic, 350Chevy Volvo 280

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    Welcome. Revs and horsepower are bound to take a toll on drives but what really kills them are hard holeshots and air time (re-entry). Everyone speaks highly of the KC drive though so they must be pretty strong.
    Lake St. Clair, Lake Huron, Lake Erie, Lake Oakland

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    Update pics. Final measuring of push rod length, and then it's time for final assembly.

    Thinking about a Dyno tune, but don't know of anyone in the Bay Area with an engine dyno. (San Jose, CA)

    The exhaust is not going to fit with these valve covers, so they have to go.... Sad because I liked the look and machined them flat....

    Headers still need the water inlets installed, and need to be cleaned up. When I started, I cared about the appearance and having small welds, then I realized I still work for a living and need to hurry up... The rough parts are at least buried in the bilge!

    How would I plumb a crank mounted water pump? Do I keep pulling through the factory outdrive pump and get rid of that impeller?


    And thank you for any help and knowledge.image.jpegimage.jpegimage.jpeg

    more to come!

    Best,
    Matt

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    Don't get rig of the out drive pump.

    Quote Originally Posted by 22classic View Post
    How would I plumb a crank mounted water pump? Do I keep pulling through the factory outdrive pump and get rid of that impeller?

    I believe you need to keep the impeller and housing in the drive; not sure an engine mounted sea pump would pull the water thru.
    If you need higher flow for your new engine you can add external water pickup at the transom like a inboard or old TRS drive. This would feed your crank driven sea water pump. The guys with high HP Alphas use the raw water pump in the drive to feed a drive shower when they go to the external feed.
    Thank you, Patrick
    1994 18' Classic 350Mag Alpha

    Previously owned Donzis -
    1996 22' Classic, 502Mag Bravo
    1987 20' Minx, 350Mag Alpha
    1975 18' Classic, 350Chevy Volvo 280

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    Quote Originally Posted by 22classic View Post

    How would I plumb a crank mounted water pump? Do I keep pulling through the factory outdrive pump and get rid of that impeller?

    Best,
    Matt
    I've done this to every Donzi I've worked on. Outside, remove the Alpha impellor, the pump design is too small, install a Stainless Marine transom pickup like in the picture. Remove the connecting hose between the bell housing and the external gimbal plate.
    Inside, remove the hose aqdapter bolted to the gimbal housing and cap it (parts are available from Merc). Mount this crank driven Johnson raw water to the crank balancer:
    http://www.marineexhaustmanifolds.co...ater-pumps.htm

    In the pictures, see the transom pickup and strainer. Also notice the cap on the inside of the gimbal housing where the hose adapter was.



    George Carter
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    http://kineticocentralfl.com/


    “If you have to argue your science by using fraud, your science is not valid"
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    Quote Originally Posted by 22classic View Post
    As for planning my prop do you have any suggestions? I was thinking something around a 26-27 prop? I should be making somewhere around 600-650hp, but that is only a guess. Do one brands work better than others?

    hopefully the attachments come through.
    26~27" will be too small. At about 550hp I was running a 27" 4 blade or 29" 3 blade. You'll probably run out of prop at 650hp. Every boat handles differently to different props. If you can, try and borrow from people to try out. It seems most prefer 4 blades. For my boat, I preferred a 3 blade. I tried a 28 Bravo, 27 Hydromotive QIV, 29 Mirage Plus and a 28 Tempest Plus (supposedly tweaked to a 29). Mirage was good but experienced blow out. Blow out never seemed to be a problem for others, but it was for me. Tempest ran very similar to the Mirage, but no blow out. 4 blades were never a fun ride, (I have lots of brown shorts now ) but the Hydro was much better than the Bravo. Lots of guys really like the Bravo though. Sorry, not much help.
    Why is faster never fast enough.

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    Most 4 blades lift the stern

    For an old school V bottom, you need a bow lifting prop. Most 3 blade round ear props are bow lifters. A 29/30" pitch Mirage/Mirage plus or Turbo 1 (if they make one that big) would be good options to try. A stock Bravo or Hydro QIV is going to lift the stern too much. A 30" pitch Bravo 1 that has been modified for bow lift would be another good prop to try if you can find one; BBlades made a 28p bow lifting B1 for me that worked great on my 24' Superboat.
    Thank you, Patrick
    1994 18' Classic 350Mag Alpha

    Previously owned Donzis -
    1996 22' Classic, 502Mag Bravo
    1987 20' Minx, 350Mag Alpha
    1975 18' Classic, 350Chevy Volvo 280

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    Quote Originally Posted by Pat McPherson View Post
    A 29/30" pitch Mirage/Mirage plus or Turbo 1 (if they make one that big) would be good options to try.
    Won't find a Turbo in that size. I tried. You can't go wrong with the M+. (I think I'm the only guy that ever had issues with one). FYI, I tried the Tempest on the recommendation of Mr. X.
    Why is faster never fast enough.

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    I like Mirage over a M+

    Quote Originally Posted by yeller View Post
    Won't find a Turbo in that size. I tried. You can't go wrong with the M+. (I think I'm the only guy that ever had issues with one). FYI, I tried the Tempest on the recommendation of Mr. X.
    I have found my 22 Donzi runs too loose with the Mirage+; more stable with a regular Mirage or Turbo 1. The M+ may have too much bow lift for my liking. No prop as good as a Rev 4 but those stop at 25p.
    I did run a "labbed" Mirage plus 27P on my 24' Superboat with great success; vary fast +2-3mph over my "labbed" 28p B1. I tried a Tempest on my Superboat but I blew out often; I think that's more of an outboard prop.
    I think Power Tech may have some options but not sure if there is a company that has a test program.
    Thank you, Patrick
    1994 18' Classic 350Mag Alpha

    Previously owned Donzis -
    1996 22' Classic, 502Mag Bravo
    1987 20' Minx, 350Mag Alpha
    1975 18' Classic, 350Chevy Volvo 280

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    Quote Originally Posted by Pat McPherson View Post
    I have found my 22 Donzi runs too loose with the Mirage+; more stable with a regular Mirage or Turbo 1. The M+ may have too much bow lift for my liking. No prop as good as a Rev 4 but those stop at 25p.
    I did run a "labbed" Mirage plus 27P on my 24' Superboat with great success; vary fast +2-3mph over my "labbed" 28p B1. I tried a Tempest on my Superboat but I blew out often; I think that's more of an outboard prop.
    I think Power Tech may have some options but not sure if there is a company that has a test program.
    Looks like you had the complete opposite results with the Mirage and Tempest that I did.
    I have heard of two companies that do a test/exchange program. Can't remember them both, but I know BBlades does...or at least they use to. If I remember correctly, you had to buy a prop and for $25 + shipping you could exchange it at least a couple of times
    Why is faster never fast enough.

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    Will a Mirage+ hook up with a -2" shorty?
    Lake St. Clair, Lake Huron, Lake Erie, Lake Oakland

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