mercury tech

[triplethreat0809]

how do u tell the diff between a 2.4 and a 2.5 and a 150 from a 200:confused:

[Jay Smith]

All 2.5's are 3.500" bored 2.4's are smaller ...All 2.5's have 2 line up dowels on top and bottom of the heads.

Most 150's have a slot cut in the exhaust port at the top of the sleeve .. 99% of 200's don't...

Hope that helped...
Jay

[ChrisCarsonMarine]

In the beginning,1976,there came the first 60 degree merc Black Max,175 hp,2.0 litre,3 1/8 steel bore.Similar motor in 1977.In 1978 a 200 hp vertical reed 2.4 chrome bore, was introduced,produced through 1982,joined in 1881 by a one year only 7 leaf horizontal reed 225 hp.In 1983 all 200's were 2.4 litre 5 leaf horizontal reed chrome bore,except for the introduction of an oil pump boss this motor remained very similar through 1990.During this time the 175 began using the 2.4 block,while the 150 and 135 mostly used the 2.0 platform.1991 is a transition year,things are mixed up a bit,but the noteworthy points to ponder are:The first 2.5 is built,and it uses dowell pin heads,the same year the 175hp made use of the virtually unknown one year only "fat block" 2.4 litre steel bore block,ALSO using dowell pin heads.Remember as well,even after things stabilize a bit in 1992,and the 2.4 dowell pin block is forgotten,the steel bore 2.0 150 and 135 hp motors are still being built,and will continue through the 90's,and all 91's,2.0,2.4,and 2.5 and 92 and on 2.0's and 2.5's have dowell pin heads...Check bore size and reference the carbs,you should be able to determine hp,chris

[Way2slow on H2O]

That's an accurate history lesson there Chris, lol.

And I don't know what happened in '91 but it sure gets confusing.... bottom guided rods, exhaust relief slots on 200hp, some 200hp had 7 pedal and some had 5 pedal, some 2.5 blocks had 2.4 sleeves and pistons..... you never know what you're gonna find when you open er up. We've had a record # of '91's come through in the past month.