Mating Engine to Mercrusier problem

[fordlove]

Hello all, here's my situation. I have a 1981 Sea Ray, 24ft with a 260hp 350. engine went bad, and I ordered a new from Summit. I asked specifically which engine would be a direct replacement for my year and they gave me a part number. I ordered, it arrived. Unpacked and started swapping stuff over. First issue was the intake didn't fit right, so did some research and Summit told me they send me an engine 350 1987-95 GM. They wouldn't take it back for exchange because I had it too long (2 months before I started swapping) and I unpacked it. So, intake didn't fit right, so I had to order a new one. A couple other adjustments later and I've got it mostly together. Pulled it off the engine stand, and went to install the flywheel. Would you believe that doesn't fit either? So then the mercruiser engine coupler doesn't fit either (picture below).



Anyone have any idea where I can get one that will match up to my engine with a new flywheel and will still mate up to my outdrive. I'm not sure if there's a difference between mercruiser outdrives from 81 to 87.

Thanks for the help, google isn't being nice to me today.

 

[Paintman1960]

That coupler is for a early block
2 piece RMS
Did you order a votec ?
Centerbolt vavle covers?

 

[fordlove]

That coupler is for a early block
2 piece RMS
Did you order a votec ?
Centerbolt vavle covers?

I'm not sure what a votec is, and it does have centerbolt valve covers.

According to Summit Racing, what they sent me was:


HME-VMM6:
VMM6 5.7 / 350 1987-95 GM 5.7 / 350 Complete with oil pan, front cover and valve covers installed. 2 bolt main, 1 pc rear seal, flat tappet cam, valve covers bolt thru center, steel front cover. 12 bolt intake. 5.7L Base and Inboard. 260 Block casting numbers 548, 526, 148, 638

 

[Paintman1960]

Thats a vortec engine,
You need a different coupler
Bolts to flywheel instead of crankshaft

 

[fordlove]

Thats a vortec engine,
You need a different coupler
Bolts to flywheel instead of crankshaft

Any idea what coupler I need? Maybe a part number or something I can look up?

 

[Paintman1960]

Quick search shows this but there are others https://www.partsvu.com/47-2323-cou...erm=4574655569090981&utm_content=All Products

 

[Paintman1960]

Check yer flywheel for the bolt holes too make sure tho
Im guessing ya need a diff. FW

 

[fordlove]

Check yer flywheel for the bolt holes too make sure tho
Im guessing ya need a diff. FW

Ya, I need a flywheel too. So, any from NAPA should be OK?

 

[Paintman1960]

Should be , no different in those parts
IDK if NAPA has couplers
you are gonna like that engine, fer sure , much better power
Compared to previous engine , I'm sure of that !!

 

[Rick Stephens]

Thats a vortec engine,
You need a different coupler
Bolts to flywheel instead of crankshaft

That is NOT a Vortec. 12 bolt intake is not Vortec, 8 bolt intake is Vortec. 1995 and newer is Vortec.
1 pc rear main.

 

[Paintman1960]

My mistake, His post does say center bolt pattern on the covers
Idk
I could be all wet on this , lol

 

[achris]

HME-VMM6:
VMM6 5.7 / 350 1987-95 GM 5.7 / 350 Complete with oil pan, front cover and valve covers installed. 2 bolt main, 1 pc rear seal, flat tappet cam, valve covers bolt thru center, steel front cover. 12 bolt intake. 5.7L Base and Inboard. 260 Block casting numbers 548, 526, 148, 638

There's the problem. Your 1981 had a 2 pc rear seal. The one piece has a completely different bolt pattern, so you need a new flywheel and the later style coupler.

Thats a vortec engine,

Nope. Centre bolt valve covers have no bearing on it being vortec or non-vortec. The ONLY way to confirm is the number of or angle of the screws holding the intake manifold to the heads.

Chris........

 

[Bondo]

My mistake, His post does say center bolt pattern on the covers
Idk
I could be all wet on this , lol

Ayuh,.... You sure are,.... Everything you've said in this thread is Wrong,.....

Welcome Aboard fordlove,..... You need an '87 or newer Chevy flywheel, that matches the diameter of the old motor, probably the 14", 168 tooth,.....
or possibly, the 12" 153 tooth,...
Yer old motor has a 3.5" bolt pattern, the 1 pc version is a 3" pattern,...
305, or 350, they're all the same,...

Then ya need this retro-fit coupler that matches the smaller bolt pattern crankshaft, 'n is like the old coupler to match the MC-1 flywheel cover, to mate up to the MC-1 drive,.....
The coupler paintguy posted won't fit inside the flywheel cover you have,....

As noted above, the 1 pc. rear main seal came out in '86/ '87, 'n the heads changed to the "fuelie" heads,....(the center intake bolts changed their angle to straight down)
The Vortec heads came out in '96,.....(the center intake bolts were eliminated)

 

[Paintman1960]

Thanks Bondo
I stand corrected and learned something
My apologies

 

[Scott Danforth]

I'm not sure if there's a difference between mercruiser outdrives from 81 to 87.

Thanks for the help, google isn't being nice to me today.

NO, the drives are very similar. however the engine on the other hand went thru 3 major design changes and a bunch of minor changes

your boat being a 1981 may have a 1980 block

first design change was block changed in 1980 for the 1981 model year. this flopped the dip stick and there were some head casting changes for accessory mounts

Next change is the heads and intake from 12 bolts with all the bolts at an angle to 12 bolts with the center bolts at a different angle. this hit about 1984

Next change came with head castings again, this time to migrate from perimeter to center mount valve covers. depending on application, this change started in 1985 and effected some 1985 model year motors

Next change came with block castings and crank shaft/flywheel/rotating assembly. this is the change from a 2-piece RMS block to a 1-piece RMS block this eliminated the rope seal for the RMS and went to a reasonably leak-free 1-piece RMS. This change happened in 1985 and stared on 1986 model year vehicles. hitting the boat market late in 1986

Next change came with certain block castings in 1987. This is to add the bosses for roller cams for certain applications for 1988 model year change.

subsequent changes are internal bits and various head castings until 1995 when the head combustion chamber was re-designed to the vortec combustion chamber. this is the gen 2 LT3 combustion chamber in a Gen 1 cooling configuration casting. the intake bolts also changed from 12 to 8 vertical.

 

[kenny nunez]

In the Sierra catalog # 18-2172 engine coupler; replaces 14505a2.
Used when replacing V6-V8 2 piece rear main seal with 3-1/2” crankshaft bolt pattern to a newer 1 piece rear main seal engine with 3” bolt pattern.
Kit comes with mounting hardware.

 

[fordlove]

So here's what I'm taking away from this. My current flywheel is part number 366861N, looking that up I get 12-3/4" Flywheel, 153 Teeth.

So I need a new flywheel that will fit an '87 350, 1 pc rear seal, same diameter, same teeth. This will allow me to use my existing starter.

Second, I need a new Engine Coupler - Sierra catalog # 18-2172, which fits the new flywheel.

Thanks for all the info. Much appreciated.

 

[Scott Danforth]

Any 1986 and later GM SBC manual transmission 153 tooth flywheel ( for 10" clutch) the should be about $70 for cast iron and $150ish for SFI rated billet steel