What's the difference btwn 150 and 165?

[tjkeller]

Hello all!

Question for whomever can answer.
What is the difference between Mercruiser 150hp & 165hp engines?

I have a 1977 Viking that I pulled a 165hp out of and and put in a 150hp
that was in a boat Dad scrapped. Both are inline 6cyl and both blocks are
stamped with the SAME GM code which translates to a 250cid engine.

Not sure the year of the replacement...Dad thought late 60s - early 70s.
From what I could tell they were the same engine but had slightly different
manifolds, diff fuel pumps, diff alternators, and wiring harness was not the same.

What can I do to get the most out of this "150"? My Viking is a big heavy
deckboat and I'll need to get all I can out of the power plant.

THANKS for any info you can provide!

Travis

 

[Don S]

Re: What's the difference btwn 150 and 165?

The 150 was used between 64 and 66 only. It was a 230 cu in. engine. the 165 is a 250 cu in engine.

 

[tjkeller]

Re: What's the difference btwn 150 and 165?

The 150 was used between 64 and 66 only. It was a 230 cu in. engine. the 165 is a 250 cu in engine.

Thanks for the reply Don.
I am perplexed though cause the GM Casting# Stamped on the Block is 377127 which translates to 250 CID.
As mentioned in my original post, the only visible difference btwn the 165 & 150 is Intake Manifold, Alternator,
Fuel Pump, & Wire Harness. Everything else including the various bolt holes on the 150 is the same as 165.

My suspicion is the diff btwn 150hp & 165hp has to do with the carburetion but I'm not sure. Also, if so, what
can I do to get more hp out of this setup. (one other noted diff is the 165 has PCV that vents to the Flame
Arrestor whereas on the 150 there is a hose direct connected from carb body to valve over)

This one is just puzzling cause I don't find much info on the "150"

Regards,
Travis

 

[Don S]

Re: What's the difference btwn 150 and 165?

The 150 was used between 64 and 66 only. It was a 230 cu in. engine. the 165 is a 250 cu in engine.

As I said before, the difference is the cubic inches, measure the bore and stroke, then you will see where the difference is.