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2 piece rear main block to 1 piece?

J

Jodowii2

New member
Alright guys I have an 88 Glasstron with a brand new 350 in it. Has a gen one merc Alfa one drive on it. Boat came originally with a 2 piece rear main engine and now has a 1 piece rear in it. Aparently there’s a difference in the bellhousing and rear mount. Sourced a 1 piece set locally. Has anyone done this swap? Starting to see some differences in things like the power steering ram and how it mounts compared to what is still in the boat. Is it as simple and just getting a newer ram? Not wanting to go through all the trouble of finding out there’s no way for it to work.

Any help or comments are welcome I’m open to ideas about how to go about this.
 
The one piece rear main seal started in 1987.

If you have a 2 piece engine with outer bolts on valve cover then it is a replacement.
If you go back to one piece then you are restoring it to original configuration.

So its easy to figure out, 1986 and older is 2 piece with valve covers with outer bolts and 1987 with center bolt valve covers is 1 piece.

Get parts accordingly.
Use this site to look at the different part numbers for each.
 
kghost said:
The one piece rear main seal started in 1987.

If you have a 2 piece engine with outer bolts on valve cover then it is a replacement.
If you go back to one piece then you are restoring it to original configuration.

So its easy to figure out, 1986 and older is 2 piece with valve covers with outer bolts and 1987 with center bolt valve covers is 1 piece.

Get parts accordingly.
Use this site to look at the different part numbers for each.
Click to expand...



Teying to get pics uploaded but I stopped by a local boat shop and talked to them took my bellhousing with me. And he looked at it said yeah that’d for a 2 piece rear main engine. And he sent me home with one for a single piece it does clear now. But need to change the rear engine mount bracket that bolts to the transom. Problem is the steering ram is different between the 2
 
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Jodowii2 said:
Alright guys I have an 88 Glasstron with a brand new 350 in it. Has a gen one merc Alfa one drive on it. Boat came originally with a 2 piece rear main engine and now has a 1 piece rear in it. Apparently there’s a difference in the bellhousing and rear mount.
As noted, by 1988, the original Glastron SBC should have been equipped with the 1 pc rear main seal arrangement.
There should be no difference in the rear engine flange (between the 1 pc and the 2 pc rear main seal engines) where the "flywheel cover" attaches.
Also, the 1988 Mercruiser A drive flywheel cover (bell housing in the auto world) incorporates the rear engine mounts.
Click to expand...




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Last edited:
I think I might have found a solution...

basic ic power industries sells a flywheel for this...

description taken from their page

“Flywheel 12.75 Inch. Fits 5.0L & 5.7L GM V8 with 1-piece rear main seal (1987 & newer)

This flywheel is needed when putting a newer engine (1987 and newer)into an older Sterndrive Application.

The older engines used a flywheel that was 12.75 inches in diameter and if you try to use the 14 inch flywheel it will usually hit the bell housing.
 
Jodowii2 said:
I think I might have found a solution...

basic ic power industries sells a flywheel for this...

description taken from their page

“Flywheel 12.75 Inch. Fits 5.0L & 5.7L GM V8 with 1-piece rear main seal (1987 & newer)

This flywheel is needed when putting a newer engine (1987 and newer)into an older Sterndrive Application.

The older engines used a flywheel that was 12.75 inches in diameter and if you try to use the 14 inch flywheel it will usually hit the bell housing.
Click to expand...

There are 2 flywheel diameters used for the SBC...... 153 tooth ring gear, and 168 tooth ring gear.
I could be wrong, but I believe that Merc's SBCs always used the 168.


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