Identify 120 vs 140 mercruiser

[italianstal27]

Morning!

So during our rebuild, we realized the exhaust manifold on our engine is actually from a 120hp. Unfortunately, I've already thrown a 140hp head gasket replacement on it >.<

SN of engine is 2769040. on boatinfo.no it doesn't differentiate between the 120 and the 140... Does anyone have a test this engine? It's somewhere between a 1963 and 1973...

-John

 

[Bondo]

Ayuh,.... The 120 hp, 153 cid. 2.5l motor has Only a pulley on the forward end of the crankshaft,....

The 140 hp, 181 cid. 3.0l motor has a pulley, 'n harmonic balancer on the forward end of the crankshaft,...

Whatever ya got, it'll run just fine with whichever manifold, 'n head ya end up with,...
Though I believe the valves can be shrouded by the cylinder walls, when a big valve 3.0l head is run on a 2.5l block, with it's smaller bore,....

I believe I've seen 3 different intake/ exhaust port designs, of various sizes,...
Matchin' is of course Best, but any combination will run Ok,...