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new 5.7 engine coupling for OMC800

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Larry Baxter

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Does anyone know if I can get a flywheel coupling for the one pc. crankshaft 5.7l chevy engine that will mate with my OMC800 outdrive. I talked to a couple of marine shops, but unless I could give them a part or cataloge number, they couldn't help me. ANYONE KNOW A PART NUMBER???????
 
there is no part number because it doesn't exist.

OMC had already gone to the Cobra drive by the time GM made the 1 pc rear main. OMC stringer mount drives 1964-1985 ONLY mate to 2 pc rear main seal engines.
 
jeez why do we keep getting these trick questions?

I just assume that someone who posts is really looking for help.

post a pic of the old coupler.
 
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The boat is a 1982 cruisers inc. holliday 22. The outdrive is a 1982. The engine I am trying to use is a 1994 truck roller engine. Are the spline counts and diameter on the one piece crankshaft coupler, the same as the coupler for the two piece rear main??? I am sure I am not trying to re-invent the wheel, as I am sure that many people would like to upgrade their engines to something more bullet-proof than 1970's technology.
 
Larry Baxter said:
I am sure I am not trying to re-invent the wheel
Click to expand...

no, just trying to mount a 1982 wheel on a 1994 engine...won't work

sell that engine and buy one that will work

any pre-1987 SBC or a new GM crate 290HP 5.7 will bolt right up to your coupler.... 1994 truck engine, not so much
 
Here are some pics of the existing hub. It would really be not too much of a problem to machine down but it is heat treated to a 56 rockwell, and I am fresh out of diamond tools and EDM machines. I find it hard to believe that someone, somewhere has not made a spline coupler for this application considering all the OMC800 outdrives out there, and the availability of "new" replacement engines omc800.jpgomc800 adapter.jpgomc899 adapter.jpg
 
You can put a (1) piece rear main ie 1987 sbc in front of a 800 Stringer!
This is how I did it . . . You will need an engine coupler for a ford 302/351 and the (six)bolts.
The crank on the SB Ford and 1987 and later SB Chevy are on 3 inch diameter bolt circle. Note that
5 out of 6 bolt holes on the ford coupler will line up to the chevy crank shaft. The sixth hole on the coupler
will need to be elongated. A milling machine is ideal for this. Next, refer to you Summit Site and order a flywheel
for 1987 Camaro w/ manual transmission. It's the same dia. and number of teeth as the one you have and you can reuse
you original starter. Then order a Quick Time 3/8" thick bell housing spacer. Helpful hint, replace your dowel pins on your
block with longer ones, they are easy to make, use a micrometer and match the diameter for a tap fit. For all of the "Na Sayers" that is how it is accomplished!
 
Oops, forgot one detail ! On the back of the ford coupler there is a pilot that centers the hub into
the back of the crankshaft. You will need to make a bushing to press on it to increase the diameter
so that it will center up on the back of the chevy crankshaft Thus, creating a hub-centric condition.
 
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