In 1991 the first year of the Mercury 2.5L motor. Mercury had an odd duck 2.5L 200hp engine. It had bottom guided 8118 rods, pumper carbs, and a wide 7 petal front half. They put out more than 200hp and were banned from race events. 7 petal front flows a lot better above 7000rpm.
http://www.odbaracing.com/wp-content...BARulebook.pdf
Page 22.
Stock 200 fishing motors allowed.
5)
No Pro Max, 240 Sport Je
t, Motorola, High Performance, Special Production, Back door
or
Custom engine blocks
allowed.
6)
No 1991 model 14 pedal blocks
allowed.
8)
No blocks from Mercury with machined rod
slots.
9)
10 pedal front halves
only.
10)
New motors with taller decked blocks with
o
-
ring heads
allowed.
11)
Only 1 gasket per set of mating surfaces, Maximum thickness
.065"
12)
HP Mercury Parts Allowed (If it is not listed it is not
allowed)
a)
Exhaust Divider Plate to mount
coils.
b)
One
-
piece HP adapter
plate.
c)
HP exhaust
tuner.
d)
HP rods bolts allow
ed. Rod caps may not be machined or ground for
clearance.
e)
HP metal cage rod bearings
allowed.
f)
Aftermarket flywheels
allowed.
g)
Stock High Performance 260 or drag Stator, Trigger, Switch Boxes, and Plug
wires.
h)
Mercury HP ECU allowed. (A
-
2, A
-
4, A
-
5, A
-
6,
A
-
8, A
-
10, A
-
13, A
-
14, A
-
63,
A
-
48)
i)
Mercury HP ECU mounting
Bracket.
j)
Mercury HP Fuel Pump
allowed.
k)
Mercury HP Fuel Regulator
allowed
************************************************
7 petal front (14 petal blocks)
vs.
5 petal front (10 petal blocks)
The 1991 200hp 2.5L engines are most easily recognized by the large single water cooled voltage regulator and the pumper carbs.
