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Thread: Fast Fred's Secrets of the OMC MOD50's Thread #1

  1. #1
    FFX-61
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    Default Fast Fred's Secrets of the OMC MOD50's Thread #1

    Thare are three power heads, guna talk about the first one the 19s.
    this is a Tradewinds motor,port exhaust standard 49ci case + .030
    uses the long rods same size as the Big twin, thare are mod 50 rods,
    the dif' bein the wrist pin hole, stock mod 50 rods run the big wrist pin and caged wrist pin bearing. the big twin rod is the best set up, thay make a kit to run the big wrist pin in the small rod hole with full complament bearing.
    steal crank, the stock mod50 19s pistons are two ring dome style with finger port tranfur holes. the case it self is the same as the production case,
    the rib under number three exhaust port is cut to let water run in to case , this moda ran no thermostat, did have a water pump, 6 amp alternater,
    the exhaust exit is also cut to except the mod 50 exhaust plates.

    the front 1/2 on this one has the same jog as the stock intake with 4 over 4
    pedal reed blocks, the reeds also had two smaller reeds on top that sat sideways with three 1" 2bbl carbs. was lookin for 100-130oct avgas out of the box.

    the Preface of the Owner Manual

    " This motor has been engineered and assembled to give the professional race driver, who desires to have a motor with extra capability, a motor which incorporates very high performance with quality and workman ship."
    thares more but to the point
    I've heard alot about how much hp this moda made on gas, 200hp, 150hp, 135hp, not !!!!!!!!! like it or not 100hp-105hp @7200rpm
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    Last edited by Ron Hill; 08-09-2022 at 08:21 PM.
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    this is the FR-19S

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    this is the 19S powerhead

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    Next is the Manawa motor , got to take some pic of it,

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    the second generation , after the 19s but before the 31M thare is but another
    MOD50 case, vary fue were made, looks just like the 19s, but in side it is vary dif', just so happens, i got one, made about 10-12more hp than the 19s
    we'll take a look at it,



    and as it would be, them mercs of the time were makin far, far less hp
    than thay would like you to beleve, like 60-75hp at the most

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    this is the reed blocks of the 19s

  7. #7
    Tomtall
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    Question Reeds

    Fred - I see no reed stops. Customery for these engines?

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    no reed stop are shown in the owners manual, I don't run stops my self on any thing, i do sometimes cut the stops way back , thare just to hold the reed in place. the Yamaha 70 ces is the only race moda i'v ever seen
    sent out with reed stops, at a minamum thay need to be cut back 50%, best to remove them ( in the yama)

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    hangin thare Tomtall
    just gettin goin, got a ton more stuff, slow on the pics, i don't do them my self
    (the pics) thanks for lookin

  10. #10
    Sam Cullis Mark75H's Avatar
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    The true purpose of "reed stops" is not to limit the reed's travel, but to reduce vibration of the reed. A more correct name might have been "dampener" rather than "stop". Some reeds in some motors will flutter and vibrate violently without a stop. At some motor speeds this can cause the reed to be bent into an S or C shape when the reed tip approaches the cage .... jamming the tip hard against the cage, causing premature failure.

    In general remove or shorten "reed stops" with great caution; sometimes it will help, sometimes it will do nothing, other times it can destroy a motor.

    This is a great thread! I can't wait to see more! Keep it coming
    Since 1925, about 150 different racing outboards have been made.


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