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Thread: Old HotRodder

  1. #11
    Sam Cullis Mark75H's Avatar
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    I agree, there are a lot of OMC models that are greatly superior to motors Merc sold to compete with them in particular power ranges over the decades.
    Since 1925, about 150 different racing outboards have been made.


  2. #12
    - Skoontz's Avatar
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    Remember, if you are not driving an OMC, you ain't got no Johnson! One thing your 75 will do that no Merc in it's age and class will do....Pull 6 skiers out of the water at one time and maintain 28-30MPH. But I'll tell yopu a story about a 75HP Johnson against a pair of Merc 1000's with speedmasters on a Switzer Catamaran........Dateline St. Charles Illinois, 1965. Dad installed a 75 Rude on a 14' Yellow Jacket and then went to Carl Stirn's Marine and bought a 17" Johnson-Oakland prop for it because the 15" was not big enough.... The race was about 5 miles long with a turn at the 2.5 mile mark, then back to our boat house. The boats rounded the turn by the gold course about 1/2 mile up river from the boathouse. You could hear the Mercs winding tight and then thr throaty sound of the V-4 side by side. My dad pulled next to the Mercs and waited until he had no more...One of the mercs buddies saw what was going on and went up front by the park with his Chris Craft inboard making waves in hopes the Cat would cut through them, while the rounded bottom of the Yellow Jacket would get tossed all over the place....

    What he did was in fact create a situation where for 100 yards, the Yellow Jacket rose over the waves on a sheet of spray and air sort of like a hydro runs. At that point, the Yellow Jacket shot out so far in front it was emarrassing to the Merc. A photo of that race was given to Lou Eppel the former service manager of Johnson and it sat on his desk for a number of years.
    Bill Schwab
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    I had a chance to hear Bob Switzer talk about how the flying wing evolved. I believe you Bill, but if I had to choose between a set-up Switzer, and a plywood Yellow Jacket with any motor - - - well.


    I'm in the process of installing a Hot Foot for my twins. The tech guy at T-H Marine says he doesn't think it will work. I didn't tell him I was an old hotrodder, and could make almost anything work. we'll see.
    I have a question about compression. The pistons are down in the hole about 1/4". If I cut the piston dome, say about .060, and cut the deck around .100 that would bring the mass of the piston up .040. More compression without disturbing the flame pattern by reducing the combustion chamber a bunch. How about fly-cutting for spark plug clearance?

  4. #14
    Sam Cullis Mark75H's Avatar
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    That would make more power, but doesn't solve the other issue.
    Since 1925, about 150 different racing outboards have been made.


  5. #15
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    Quote Originally Posted by 50sFlash View Post
    I had a chance to hear Bob Switzer talk about how the flying wing evolved. I believe you Bill, but if I had to choose between a set-up Switzer, and a plywood Yellow Jacket with any motor - - - well.


    I'm in the process of installing a Hot Foot for my twins. The tech guy at T-H Marine says he doesn't think it will work. I didn't tell him I was an old hotrodder, and could make almost anything work. we'll see.
    I have a question about compression. The pistons are down in the hole about 1/4". If I cut the piston dome, say about .060, and cut the deck around .100 that would bring the mass of the piston up .040. More compression without disturbing the flame pattern by reducing the combustion chamber a bunch. How about fly-cutting for spark plug clearance?
    My experience with raising the compression on deflector OMCs is that you will gain acceleration mostly but that extra can be applied to more prop [again preferably SS]. As far as the 'foot print' its still a problem but if it will get out of its own way off the line & go a little faster, not a bad thing. I can also tell ya that sure more motor will get ya there but if your willing to put time into what you have you can improve it. Good Luck.

  6. #16
    - Skoontz's Avatar
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    I'm thinking you are approaching this thing in reverse of the way you should.

    I would fist do everything you can to maximize the hydro dynamics and bottom of the boat. Things like if you have a hook, if the transom does not have a perfect angle to the bottom and is curved ( thast needs to be a hard angle) things like that.

    Once you gain from below, then go up top. If you do too much at once, you may end up not seeing much. Kind of like dropping a 572 Chevy crate motor in a Chevelle without adding a good set of ladder bars...Jump on it hard off the line, and it is going to bunny hop all over.

    In that application, you would do suspension work forst, tranny, rear end, traction control devices, then the big motor.'

    Same thing on the water.

    The story I passed along was just a couple guys out river racing with run what they brung situations. If you want to see what a 75HP OMC can really do in stock form with just lower unit and a good boat, see if you can find the footage of the Star Flight Too, which was a box stock 89.9 cubic inch OMC engine, with a racing gear case. The boat ran around 117? give or take. That will give you the idea of what we are talking about here. All the mods were below the water.
    Bill Schwab
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    The pictures I saw of star flight too was a highly modified motor with carbs on the side on the defuser plates.
    I have done the hull. New floor, stringers and transom. There's no hook or hog. That's just fine, and there's nothing I can do about the aerodynamics of the lower unit.



    I want to know if anyone has cut the deck, rather than mill the heads on a 2 cylinder OMC. I can't be the first guy to think about this.

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    Quote Originally Posted by 50sFlash View Post
    The pictures I saw of star flight too was a highly modified motor with carbs on the side on the defuser plates.
    I have done the hull. New floor, stringers and transom. There's no hook or hog. That's just fine, and there's nothing I can do about the aerodynamics of the lower unit.



    I want to know if anyone has cut the deck, rather than mill the heads on a 2 cylinder OMC. I can't be the first guy to think about this.
    Ive heard of it being done but havent myself. The OMCs Ive got the pistons come to the top of the bore so the heads the way on em.

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    Thanks Mike, I was surprised to see the pistons not come to the top. I hope this shows it OK. This is at TDC. Still looking for someone that has run these before.



    I got the Hot Foot ready with both cables. It doesn't return well, but I think after the motors are rebuilt and the advance freed up it should be OK.




  10. #20
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    Default Starflite Too

    Actually, they went to great lengths to make a power head adapter plate and stack that bolted to the bottom of the block, so they could run a basically stock power head. The vast majority of the work was in the Hubbell over drive gearcase and the tower. When the record was set the engine was only turning 4900 RPM.

    What is your goal by decking a block, are you looking for more RPM? Torque? There will come a point where you can't push the bottom end any faster no matter what you did on top.

    Don't get me wrong here, it looks like a fun venture, I just hate to see anyone sink allot of time and money into something that will need even more money to make it really work at it's best.
    Bill Schwab
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