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Thread: OMC 1 3/8" carbs

  1. #21
    Team Member LittleCharger's Avatar
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    Quote Originally Posted by filthy phill View Post
    too much smoking the green stuff.

    but if it keeps you happy then carry on, it dont hurt anyone.
    We run into the 60's no problem with our two cylinder and we are set up to circle race, limited to sst45 specs for porting and run less compression then a spec sst45 motor. Lots left on the table to go faster in a straight line

  2. #22
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    Quote Originally Posted by LittleCharger View Post
    We run into the 60's no problem with our two cylinder and we are set up to circle race, limited to sst45 specs for porting and run less compression then a spec sst45 motor. Lots left on the table to go faster in a straight line
    I just thought Osa is really brave to take that thing out in open waters and hop over waves with it. He was undefeated in that little boat.

    Ya if Osa went up with the set up and allow the 12p Tunnel Boat prop surface it would have been a lot faster.
    He is draggin the gear case thru water and not allowing prop to ventilate, that's why rpms @ only 6,000..................

  3. #23
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    not at those rpm and prop sizes you dont

  4. #24
    Team Member LittleCharger's Avatar
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    Quote Originally Posted by filthy phill View Post
    not at those rpm and prop sizes you dont
    Seems reasonable to me he's running a sst45 case

  5. #25
    Team Member zul8tr's Avatar
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    45ss has 1:1 gears per APBA

    http://www.apba.org/sites/all/files/...N%20022515.pdf

    with 12" pitch at 6000 and 1:1 gears theoretical speed no slip = 68 mph
    61 mph slip would be 10.5%
    His posted 61 would be reasonable. I have seen passes at 60 by GPS and that boat in the video is there.
    " Three may keep a secret if two of them are dead" Ben Franklin
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    Location: SW Orlando, Fl

  6. #26
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    Don't bother guys, simple Phill is pretty simple when it comes to math probrems

  7. #27
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    there is plenty of posts and pics on other forums about this boat and motor,
    go check out the pics of it with your sharpeye...
    you obviously believe this is a genuine omc race motor .

    I did not know that a shifting gearcase can be 1to1 ratio , I thought that was the non shifting special and rare gearcase.

  8. #28
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    In the VIDEO the Evinrude 45ss Osa ran had the original 45ss Gearcase with a 12p tunnel boat prop.

    I mentioned to Osa that a nitro foot w/low water pu & 11 x 21 would carry that V-hull and not break loose as much........

    This same motor in the VIDEOoriginally did 73 mph @ 7,200 in quarter mile drag on a 13' Tomcat Tunnel and dominated it's drag class in SE Virginia.
    Likes hupiveneilija liked this post

  9. #29
    Team Member JohnsonM50's Avatar
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    Quote Originally Posted by filthy phill View Post
    the carbs talked about here are twin barrel carbs, no way to fit them on a twin cylinder motor.
    they are for the v4 motors and have just the two bodies, 1 up top and 1 down the bottom.
    Not true, I've done it. With some experimenting got it to work very well on a 31.8 OMC twin cross flow. It was within 1 mph on top & boosted mid range nicely. It also started better.

  10. #30
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    Quote Originally Posted by JohnsonM50 View Post
    Not true, I've done it. With some experimenting got it to work very well on a 31.8 OMC twin cross flow. It was within 1 mph on top & boosted mid range nicely. It also started better.
    Thats a stock manifold. I removed single carb studs & shaved the aluminum down till it had a flat surface big enough to accept the 85hp 2 barrel carb. I made an adapter plate with 4 studs to mount the carb. There is a center block epoxied into the stock manifold to separate the barrels, 1 each cyl. The adapter plat is epoxied onto the cut manifold & thru screwed where the manifold studs were. a couple are under the carb so I used flat head SS screws there. It sealed right 1st try & ran 1st try. Next is going to be a V block reed set up but that will be more difficult. When done it will drastically reduce crank case volume & eliminate the pre historic 'wall' of reed obstruction.

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