Repowering my 1979 Mercruiser: What will fit and what won't

[84EdH]

I have a 1979 Mercruiser with a 350 engine that is shot. I want to upgrade the motor to a new gm 350 Vortec marine engine. I bought a complete low hour 1995 350 Merc alpha engine for parts.

First my old Merc had a 12 3/4 inch flywheel with the old style coupler. I plan to use my old pre-alpha outdrive, transom mount and bell housing. I have heard the 14" flywheel on the 1995 wont fit my bell housing. However, it does fit. I bolted it up to the 1995, with the 1995 starter and it seemed to crank fine. Is there a problem with this I don't know about?

also, will the triangular coupler that came with the 1995 fit the old transom mount and outdrive?

second question: my old wiring harness to the dash has eight pins, the 1995 engine wiring harness has 10. Is there an adapter or easy way to mate these up?

3rd question: will the power steering pump hoses on the 1995 just connect up to the power steering setup on my old merc setup?

4th the new center rise exhaust manifolds have an elbow off the rise that is oval on the outlet end. My old merc exhaust Y is round. Are there parts to purchase to match these up or do I just adlib with hoses etc. ?

Ed

 

[Pete104]

Re: Repowering my 1979 Mercruiser: What will fit and what won't

See if you can find the OEM service bulletin on this, where you are located. It's #86-14, that's a quess. But nothing from the OLD fits the NEW. It starts with the exhaust tube, and just gets worse from there. Your old flywheel housing won't fit the updated exhaust.
See if you can find that service bulletin, it save you alot of headaches! In the mean time, keep the new engine "PICKLED"!

 

[Bondo]

Re: Repowering my 1979 Mercruiser: What will fit and what won't

I want to upgrade the motor to a new gm 350 Vortec marine engine. I bought a complete low hour 1995 350 Merc alpha engine for parts.

Ayuh,... While the 95 is Newer than yer 79,...

It ain't a Vortec headed motor....

Vortec was Intro'ed in 1996....

 

[84EdH]

Re: Repowering my 1979 Mercruiser: What will fit and what won't

Bond-o, yes 96 was the intro to vortec and thats what I am shopping for. The 1995 parts engine has exhaust manifolds, starter, alt. power steering, thunderbolt iv ignition, thermostat housing, hoses, brackets etc. that will transfer to the vortec. I know I need an 8 bolt intake manifold and an electric fuel pump.

the issues in my thread were about the few things I am not sure about. Usually, a 12 3/4 inc flywheel for the vortec is recco. for my old 2pc rear seal and outdrive set up, with a conversion coupler. (old style couplerwith appropriate bolt pattern.) I was surprised to see the 14 inch from the 1995 fit in my old bell housing.....and that posed the question about the coupler.

the electrical connection, and the exhaust hookup were the other issues as described.

thanks

Ed

 

[Bondo]

Re: Repowering my 1979 Mercruiser: What will fit and what won't

Bond-o, yes 96 was the intro to vortec and thats what I am shopping for. The 1995 parts engine has exhaust manifolds, starter, alt. power steering, thunderbolt iv ignition, thermostat housing, hoses, brackets etc. that will transfer to the vortec. I know I need an 8 bolt intake manifold and an electric fuel pump.

the issues in my thread were about the few things I am not sure about. Usually, a 12 3/4 inc flywheel for the vortec is recco. for my old 2pc rear seal and outdrive set up, with a conversion coupler. (old style couplerwith appropriate bolt pattern.) I was surprised to see the 14 inch from the 1995 fit in my old bell housing.....and that posed the question about the coupler.

the electrical connection, and the exhaust hookup were the other issues as described.

thanks

Ed

Ayuh,... The Coupler/ flywheel issue can be played either way, so long as the starter matches the flywheel....

The electrical just needs to be sorted out,...
Probably the easiest way is to update the Boat side of the wiring...

For the Y-pipe, ya just gotta do whatever it takes...
No "Easy Button" for that...

 

[Glasply]

Re: Repowering my 1979 Mercruiser: What will fit and what won't

I put a new 350 in place of an old 305 with a pre-alpha drive. The bolt pattern on the flywheel is different, so while the 14" flywheel fits inside the bellhousing, the coupler won't bolt up. You need the adapter coupler that looks like the old style ball (not the triangle plate) with a bolt pattern for a newer engine. The part number I bought and used is GLM11520.

 

[84EdH]

Re: Repowering my 1979 Mercruiser: What will fit and what won't

Glaspy, actually, the triangular coupler bolts up but it doesn't clear the back of the bell housing right at a point behing the rear motor mounts. So, your right, I need the conversion coupler. At least I wont have to buy a flywheel too.

thanks

ed

 

[Bondo]

Re: Repowering my 1979 Mercruiser: What will fit and what won't

Glaspy, actually, the triangular coupler bolts up but it doesn't clear the back of the bell housing right at a point behing the rear motor mounts. So, your right, I need the conversion coupler. At least I wont have to buy a flywheel too.

thanks

ed

Ayuh,... that should be part # 18-2172, right here from iboats..

 

[candrive55]

Re: Repowering my 1979 Mercruiser: What will fit and what won't

Hi please post what you do with your exhaust. I am near that point too.
Same problem

 

[nlinetec]

Re: Repowering my 1979 Mercruiser: What will fit and what won't

I have 1 kit in stock for the exhaust at murphysmarine.com. You can also find it on eBay using this link. http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=360365964149&viewitem=