OMC 260 hp engine needs rebuilding...

[Leigh Stivers]

I have 1979 OMC 260 hp OMC engine (GM 350" block) that needs to be rebuilt,
and I was wondering, if it would be cheaper/possible just to get a rebuilt
automotive 350 GM long block rather than having a marine mechanic do the
rebuilding. Are there any differences in the construction/alloy of a
marine block compared with an automotive block? What about the camshaft,
is the OMC version special in anyway?

Thanks,
Leigh....@dptechnology.com

[Carl Cathcart]

Yes there are differences between a marine block and automotive block.
The big difference is the way the engine gets cooled in a boat versus
an automobile. The head gaskets may be different to allow different
water paths etc. The good news is that the 260 hp (350 block) is about
the most common marine engine out there and therefore are a dime dozen.
I'm looking at a Doug Russell ad (508)791-4917 right now and they're
asking $1595.- for that engine which includes manifolds risers and
carburators. Another good source is Engine World in Tynsboro Ma. (I
think). They do not rebuild salt water blocks and may be less expensive.
Make sure you know if you want left hand or right hand and two or four
bolt main.

[sunrise@midnight]

Leigh,
Here's someone else to try
Sequel Marine
Johnson & Towers
1599 Albany Ave
Atlantic City, NJ 08401
609 348 0801 voice
609 348 2276 fax

The 'phone nos. are from last year and I was talking to them, but
couldn't get my mechanic, myself, and the boat together at the same
time.
Maybe this year, before it blows up.

Good luck
Dale

[Bryon Kass]

Leigh Stivers wrote:
>
> I have 1979 OMC 260 hp OMC engine (GM 350" block) that needs to be rebuilt,
> and I was wondering, if it would be cheaper/possible just to get a rebuilt
> automotive 350 GM long block rather than having a marine mechanic do the
> rebuilding. Are there any differences in the construction/alloy of a
> marine block compared with an automotive block? What about the camshaft,
> is the OMC version special in anyway?
>
> Thanks,
> Leigh....@dptechnology.com

The engines are very different. The automotive doesn't use stainless
or copper in any gaskets or brass freeze plugs. The camshaft is
different and the crank may be of different alloy or method of
manufacture. Most boats that I have seen with this type of convertion
have been a headache. The best thing to do is buy a marine base engine
and add your accessories. At this time you should assess the need for
fresh water cooling to extend the new engines longevity. A good used
engine is another alternative. We can get marine engines in Ford block
to replace that one. We are looking into buying the Chevies direct
from a marinizer.
Bryon Kass
webmaster and
Custom Design
150 Mechanic St.
Foxboro, MA 02035
508-543-9068 or fax 508-543-5127
in THE ENGINE ROOM http://www.ici.net/customers/cusdn

[Kimball Sant]

Leigh Stivers wrote:
>
> I have 1979 OMC 260 hp OMC engine (GM 350" block) that needs to be rebuilt,
> and I was wondering, if it would be cheaper/possible just to get a rebuilt
> automotive 350 GM long block rather than having a marine mechanic do the
> rebuilding. Are there any differences in the construction/alloy of a
> marine block compared with an automotive block? What about the camshaft,
> is the OMC version special in anyway?
>
> Thanks,
> Leigh....@dptechnology.com

I replaced my chev 350 engine last year. Picked up a long block with
marine conversion for 1100 bucks. Yes there is a difference. Brass
freeze plugs, and a heavy duty (RV Type) camshaft. all the accessory
parts from the old engine go onto the new one, even with a long block.
You are probably going to want a 4 bolt main, altho some people say it
doesn't make a difference. Be sure you know the engine rotation
direction. My new engine runs very well.