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Thread: Mirage Tomcat Resurrection

  1. #31
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    Note the steering coaming pulley up forward, several guides to reduce cable flop, leading aft to a shackle attachment at the steering bar. (I think this is a grand prix?)

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    mini tunnel boats for sport, now an experimental Sport C added to the fleet.

  2. #32
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    Several hardware items in this picture. You can see the steering pulley and a cable guide. A PWC mirror is mounted to the cockpit top edge (mirrors required for all APBA tunnel boat racing classes). The 1/8" plastic tube hanging below the mirror is the cooling water indicator. It's attached to the pee tube outlet on the motor. If it's squirting steady you're good. If its spurting, or dry, the motor is jacked up too high get back on the trailer and drop the motor down before it melts down. The orange duct tape with sharpie enhancement is my trim indicator. The cable on the bottom moves left-right with motor power trim. It's just a throttle cable attached to the motor trim bracket, and cut off at the cockpit so the end will move across the dash. If you can, leave the core long enough so it reaches across your gauge even at the shortest trim setting (this one is cut too short), so you can feed it though an eyelet or such. That way it doesn't flop around, or sag too low when trimmed all the way down. Notice the tachometer, this is a sierra/teleflex brand carried by many marine stores. Any gas engine tach will work, I think this is on the 4 cylinder setting but I'll confirm. This one reads up to 8,000rpm. The Tohatsu 2 cylinder 40hp makes good power up to 7,000-7,200rpm. If your prop is too small you may see even 7,500. With a 7k tach you wouldn't know if the prop is just a little or a whole lot too small (prop height too high, trim too far out, and other problems can also lead to excessive rpm's). The heavy duty velcro on the dash top right is for a Garmin gps, and kitchen timer for 3 minute clock starts for racing.

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    mini tunnel boats for sport, now an experimental Sport C added to the fleet.

  3. #33
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    A brass tube has been glued into the pee outlet with locktite. The indicator tube that goes to the mirror can then be slipped on. Many other motors, like OMC's, already have a hose barb and tube inside the cowling that's easier to tie into.

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    mini tunnel boats for sport, now an experimental Sport C added to the fleet.

  4. #34
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    Here is the back end of a Tomcat. The prop height is probably too low in this picture, and if I remember it ran better with less setback than this setup. The plywood blocks behind the aluminum plate, have now been removed in front of the plate, to shift the motor 1.5" farther forward towards the transom. Steering torque was reduced and top speed gained 3mph.

    Note the slotted holes and bolts in the bracket. On this setup you can loosen the bolts, support the motor skeg with a bottle jack, raise or lower motor prop height, and re-tighten the bolts. Only takes a few minutes at the boat ramp to adjust height. Once you're in the range, 1/8-1/4" adjustment or less can make all the difference. Corner handling and spinouts, vs top speed and overall motor rpms, all vary with small height changes. If you're way deep, it can take a couple inches change before finally getting to that sweet range.

    The bottom 2 pictures give an approximate prop height. The upper is a Tomcat. The lower is a home built experimental, but still a rough idea of how high the motor can run. For racing we can NOT modify the OEM water intake grate. For recreational use, especially on some motor brands, it can help to jb weld up the top half of the water intake on the sides of the gearcase. This keeps it from sucking air, while the lower half provides enough flow at rpm to cool the motor. With the 2 cyl Tohatsu you'll run out of handling before you run out of cooling water.

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    mini tunnel boats for sport, now an experimental Sport C added to the fleet.

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