Alpha 1 Sterndrive Compatibility w/ a 70's era I6 Motor

[WOEISMEIGOTTA470]

I need some help here:

I have found myself a beauty of a motor for sale, I'd like to know if it will mate up to my existing GEN 1 Alpha assembly and drive. The motor in question is a 70's era GM inline 6, mercruiser 165. It is a full rebuild and has never been installed or run. It will be replacing my tired old merc 470 FWC I4.

Now the seller also has the matching outdrive and transom assembly that goes w/ the 165 motor. So worst case I suppose I could just swap the older pre-alpha stuff into my boat. But I'd much rather keep my more modern and improved alpha 1 setup w/power steering, etc. and save myself the extra hassle and work just to put something more vintage in.

So again, will the 165 I6 motor bolt up to my alpha 1 drive and transom assembly?
Any words of wisdom here are greatly appreciated! I don't want to miss out on a great deal and a strong motor. Thanks.

Here is my boat project thread: http://forums.iboats.com/showthread.php?t=576226&p=3958967#post3958967

 

[Bondo]

Re: Alpha 1 Sterndrive Compatibility w/ a 70's era I6 Motor

I need some help here:

I have found myself a beauty of a motor for sale, I'd like to know if it will mate up to my existing GEN 1 Alpha assembly and drive. The motor in question is a 70's era GM inline 6, mercruiser 165. It is a full rebuild and has never been installed or run. It will be replacing my tired old merc 470 FWC I4.

Now the seller also has the matching outdrive and transom assembly that goes w/ the 165 motor. So worst case I suppose I could just swap the older pre-alpha stuff into my boat. But I'd much rather keep my more modern and improved alpha 1 setup w/power steering, etc. and save myself the extra hassle and work just to put something more vintage in.

So again, will the 165 I6 motor bolt up to my alpha 1 drive and transom assembly?
Any words of wisdom here are greatly appreciated! I don't want to miss out on a great deal and a strong motor. Thanks.

Here is my boat project thread: http://forums.iboats.com/showthread.php?t=576226&p=3958967#post3958967

Ayuh,.... Not easily....

The rear motor mounts are different, the transom assembly is different, 'n the input shaft is different...

It Might be adaptable, but you'll need Both piles of parts, 'n just try fittin' it together, with different pieces of each...

 

[Oshkosh1]

Re: Alpha 1 Sterndrive Compatibility w/ a 70's era I6 Motor

I also have a "Frankenboat". It's a 73 I6 in an 80's boat which originally had a 3.0L in it.

Also...I don't think the exhuast will match either. You may have to get creative!

 

[Fishermark]

Re: Alpha 1 Sterndrive Compatibility w/ a 70's era I6 Motor

Now the seller also has the matching outdrive and transom assembly that goes w/ the 165 motor.

That will solve a lot of problems for you. Simply use the transom assembly that matches the 165. The outdrive will bolt up and you can swap out driveshfts easily.

The bigger problem is the additional length of the engine. If you have room for the added length, then the job is not terribly difficult. But if you have to start modifying the floor and doghouse, etc then it becomes a bigger issue.

 

[WOEISMEIGOTTA470]

Re: Alpha 1 Sterndrive Compatibility w/ a 70's era I6 Motor

Thanks for the replies... I think for $1000 I can't really go wrong, and that's for everything from rebuilt carb to sterndrive. I'll make it work somehow. The length of the motor may possibly be an issue and that's my main concern. I need to go back there and measure, or if I can find factory installation drawings that would be a big help. I might try to call up mercruiser directly come Tuesday. I will have all year to work until next season so I'm not too worried on the time/labor aspect of things If I do need to change things up a bit with the floor/doghouse.
It's good to know that there still may be a chance I can use my alpha 1 drive.
Thanks for the help guys.

 

[WOEISMEIGOTTA470]

Re: Alpha 1 Sterndrive Compatibility w/ a 70's era I6 Motor

I also have a "Frankenboat". It's a 73 I6 in an 80's boat which originally had a 3.0L in it.

Also...I don't think the exhuast will match either. You may have to get creative!

UPDATE: I have decided to join the "Frankenboat" club, and pickup this inline 6 classic motor. I did some more researching on the internets, and I realize that many of the 3.0L parts are or should be interchangeable.
To solve the exhaust issue I believe I can source modern 3.0L parts for an Alpha 1 setup. The elbow should be a direct bolt-on to the I6 manifold.
Engine Mounting/Mating: If the bellhousing bolt pattern on the I6 motor is same as the 3.0L I4, which I think it is, than I should also be able to use the alpha 1 flywheel cover off of a 3.0L. I'd need to check to see if there are any flywheel/coupler differences or any interferences with the starter.
Power Steering should bolt right in if I source 3.0L bracketry and a water pump pulley.

And that's all I can really think of for now. Wiring should be fairly simple, as well as fuel delivery and throttle linkage. I will need to figure out how the shift plate will work.

I measured and I will need to open up the engine bay a bit as this I6 motor is about 4-5" or so longer than my current 470. But I'm not too worried about it, I'll need to open up a section of the floor and shift the gas tank forward a bit.

 

[Oshkosh1]

Re: Alpha 1 Sterndrive Compatibility w/ a 70's era I6 Motor

UPDATE: I have decided to join the "Frankenboat" club, and pickup this inline 6 classic motor. I did some more researching on the internets, and I realize that many of the 3.0L parts are or should be interchangeable.
To solve the exhaust issue I believe I can source modern 3.0L parts for an Alpha 1 setup. The elbow should be a direct bolt-on to the I6 manifold.

Welcome!Lol!!
I had an issue with the elbow and the original pipe being offset about 3"...but only had about 4" of vertical clearance between the two(You can pick it up slightly in the first pic...). The PO used two heavy bellows(cut) and a piece of automotive exhaust pipe, cut and re-welded to form a very sharp 90. It worked, but the exhaust/water had a very turbulent ride. I decided to try and smooth things out. The space was too confined to bend steel, so I used Hi-temp silicone(500deg) tubing. A llittle more pricey, but EASY(just needed a razor)to cut and fit. I used two 45's joined with a SS spacer to form the needed "tight" 90. In my case(I've got the 160, the elbow is a little smaller)I needed to get from 2.5" to 3" on the original exhaust pipe. No problem. They sell reducing bends...all I had to do was cut and clamp. The temps only run about 130deg, so absolutely no worries there either.

The front motor mounts seemed to be "custom" also.

 

[WOEISMEIGOTTA470]

Re: Alpha 1 Sterndrive Compatibility w/ a 70's era I6 Motor

Welcome!Lol!!
I had an issue with the elbow and the original pipe being offset about 3"...but only had about 4" of vertical clearance between the two(You can pick it up slightly in the first pic...). The PO used two heavy bellows(cut) and a piece of automotive exhaust pipe, cut and re-welded to form a very sharp 90. It worked, but the exhaust/water had a very turbulent ride. I decided to try and smooth things out. The space was too confined to bend steel, so I used Hi-temp silicone(500deg) tubing. A llittle more pricey, but EASY(just needed a razor)to cut and fit. I used two 45's joined with a SS spacer to form the needed "tight" 90. In my case(I've got the 160, the elbow is a little smaller)I needed to get from 2.5" to 3" on the original exhaust pipe. No problem. They sell reducing bends...all I had to do was cut and clamp. The temps only run about 130deg, so absolutely no worries there either.

The front motor mounts seemed to be "custom" also.
View attachment 167012 View attachment 167010 View attachment 167011

OSHKOSH,
That motor mount looks like something similar to what I'll need to come up with. The block used to rebuild the motor was a truck block and does not have the 2 hole boss for the merc front mount (port side).

That's quite the macguyver setup on the exhaust lol, but the silicone is a good material to use.
I'm hoping I can use the following 3.0L exhaust parts:

http://www.ebay.com/itm/120-hp-140-hp-2-5L-3-0L-MERCRUISER-GM-4-CYL-EXHAUST-RISER-ELBOW-MANIFOLD-1983-up-/310421459058?pt=Boat_Parts_Accessories_Gear&hash=item48468f9072&vxp=mtr

http://www.ebay.com/itm/Mercruiser-3-0L-Exhaust-Pipe-Assy-42422-42420-Item899-/190639143803?pt=Boat_Parts_Accessories_Gear&hash=item2c62fa7b7b&vxp=mtr

The 1st link should bolt right onto the 165 manifold, as the 3.0L I believe shares the same flange. The elbow has the angled offset towards starboard to mate to the alpha 1 lower piping.

 

[Oshkosh1]

Re: Alpha 1 Sterndrive Compatibility w/ a 70's era I6 Motor

The 1st link should bolt right onto the 165 manifold, as the 3.0L I believe shares the same flange. The elbow has the angled offset towards starboard to mate to the alpha 1 lower piping.

Yes...In my case, with the 160 manifold I had no other option, as the elbows are NOT compatible between the 160 and 165. I contemplated just getting a whole new manifold, but this one is in great condition. If the need arises to replace it, I will most certainally go with the 165 manifold/elbow setup and eliminate the MacGyvering(Closer to MacGruber I think!). I used the rubber bellows piece over the silicone just for a little added clamping power. Looks goofy...but it's absolutely watertight!

 

[WOEISMEIGOTTA470]

Re: Alpha 1 Sterndrive Compatibility w/ a 70's era I6 Motor

Hey just wanted to post an update, work has been reallllly slow considering my last post, haha Anyways I have made some good strides in building up the merc 165. Yesterday I managed to grab an original mercruiser freshwater cooling kit! I also received my new alternator in the mail yesterday and bolted it up too check fitment. I picked up a 3.0L 4cylinder for cheap that's no good but it was good for parts! It was mostly valuable for the hard to find power steering parts (pump, 3-groove pulley, and brackets). I'm still in the mechanical stage of figuring things out but I feel more reassured things will work out nicely. I will be using the flywheel housing off the 3.0L to mate to the alpha 1 drive, it bolts up no problem. The exhaust manifold is a brand new Barr unit. The elbow is a more modern design with the offset needed to mate with the alpha 1 exhaust. My plans are to fwc the exhaust manifold as well, and I bought a few special parts to make this happen.

I still need to figure out the electrical wiring and plumbing of hoses and control cables. My biggest problem to solve right now is the throttle cable and linkage, since it looks to me that the offset exhaust elbow will get in the way.

Anyways here's a photo of it on the dolly: