New Rules for 2012

Formula 1 Sport Mercury 2.5 Carb

Engine block is a 5 petal front half 2.5 200hp produced from 1992 to 1999 painted. No Pro Max blocks.   
 The intent is to treat this motor on the same basis as the SST120 motor, if you can't change the 120 motor you can't change this motor.
It is also designed so that you can put all SST 120 components (dressing) on the 2.5 short block. NO O-RING HEADS

1. Please note there are 2 possible exhaust chests; the small exhaust chest dimensions are as follows: 1.03 inches (width)
    2.50 inches (height) max. and may run any head gasket the large exhaust chest dimensions are as follows: 1.10 inches
    (width) 3.90 at the runner depth and must run head gasket #840322.
         Absolutely no grinding or blending in the exhaust chest area.
2. Must use top guided rods either stock fishing motor rods or Mercury Racing 280 rod or F1 rod. No modifying or grinding
   It is recommended if you use fishing motor rod that you use rod bolt # 10-848475
3. Any production non racing, non-high performance top guided 2.5 piston. No grinding or modifying.
   The Wiseco piston # 3137 is the base to which all other pistons will be compared.
4. Any Mercury production crank is allowed with the exception of a Mercury crank with heavy metal welded into it
    (no late model race cranks).
         No grinding or modifying.
5. The replacement sleeve is the Advanced Sleeve #1041.
6. The V-6 crankshaft centerline to crankcase/intake manifold surface to be 4.42 +/- 0.01 inches.
7. Intake manifold thickness is 2.0000 +/- .015 (between carb and reed block).
8. Cylinders bored to +0.030 inches oversized must have port heights that measure .015 lower than standard bore.
9. Reed blocks are 10 port = 1.10x.056 or 8 port = 1.05x0.63 reed blocks are allowed with no modifications or grinding.
10. Any reed material is accepted.
11. The only carbs are WH-39, WH-41, or WH-46 carbs with slosh tubes and baffles.
12.  The recommended cylinder Head is part # 18787 17 Champ 2.5L head 36.5cc but you may cut a stock head as well.
13. The SSM #6 and #4 are allowable gearcases and will be inspected per the OPC homologation sheets.
14. No grinding or blending on the blocks! No blending ports or passages! If the factory didn't touch it, it shouldn't be
       touched.
15. Must use stock SST 120 tuner.

          B1   2.13 +/- .030   BW1   0.660 +/- 0.04
          B2   2.13 +/- .030   BW2   0.900 +/- 0.04
          B3   2.13 +/- .030   BW3   0.660 +/- 0.04

          T1   2.170 +/- 0.03
          T2   2.210 +/- 0.03
          TW 2.170 +/- 0.04

          E1  1.500 +/- 0.03
          E2  1.590 +/- 0.30
          EW 2.340 +/- 0.03

Mercury 200hp Model Years 1992-1999 motor
Class Displacement                   153.0

                 Venturi    +/- 0.015     1.312
Carburetor Bore      +/- 0.015    1.562
Quantity per Engine  3 duplex

Cylinder Bore            +/- .003      3.501
Piston Stroke            +/- .011      2.650
Rod Length               +/- .006      5.500
Deck Height              +/- .012      8.31
Flywheel min lbs.                         6.6

Formula Sport SST 120

1. SST 120 head may be cut to minimum head pocket depth of 0.405 all other measurements will
     stay the same.
             No fully Machined pockets.
2. May run any tuner.
3. May run any piston as long as it meets OEM dimensions.
4. May run a light weight flywheel. 
5. All other rules for SST 120 apply.

 NOTE- THE TIGHT HEADS ARE 23CC, IT IS RECOMMENDED TO RUN SHORT REACH PLUGS WITH THIS SET UP.

OMC

The only legal OMC race motor must be supplied by Sea Way Marine.