Please help with MC-1 gimbal information if you can.

[adamjr]

I am sure this has been asked and answered but I'm not having any luck with my searching to find the answer. I have a 1968 Mercruiser outdrive. It does not have any trim position or limit sensors (hockey pucks) on the gimbal. Due to stupidity of leaving the engine cover off last year snow melted and ran through the oil cap and the engine is locked. In searching for a donor boat for a replacement motor I would like to update the stern drive to one that has the hockey puck senders as well as the trim hoses that come from the bottom of the housing as opposed to inside the housing. Replacing those lines was a nightmare.

What year did Mercruiser begin using the hockey puck senders? The ads on craigslist have either inadequate pics or none at all and I'm having issues finding this info. Thank you in advance for any help. It's been a rough couple of years with physical injuries limiting my ability to get my old Starcraft back in the water and I really want to get her splashed this coming summer.

 

[achris]

What year did Mercruiser begin using the hockey puck senders?

1974.

However, the cutout in the boat is slightly different. If you're handy with a saw it's not a problem, but you need the cutout pattern to get it right.

View attachment SX Transom shield cutout template.pdf

Chris.......

 

[adamjr]

Thanks Chris. I took a quick look last night before being called away by the Mrs. Thanks for the template as well. So the Volvo SX cut out is the same as an MC-1? I never knew that. So in my case, since I already have a hull cut out, are there any hole pairs that are the same between models? My brother in law works with a guy with a CNC plasma cutting table. If he can cut a rigid template I was theorizing that I could bolt it up with any holes that were the same between the two hull plates to get the differing holes properly cut.

Here's what maybe the final question. A few years ago I scrapped a salvage boat (1988 model year) that had an Alpha-1. The out drive was long gone as were the rams, hoses, and the anodic cover for the hoses. Everything else was there. If I were to install the Alpha-1 hull plate and gimble assembly would I be able to bolt up an older style out drive provided that I have the proper length input shaft? The two donor boats I'm looking at are a 1971 and a 1978. Both have a 6 cylinder 165 HP which would be preferential to the 120 HP I am replacing.

Thanks in advance.

 

[achris]

Your current cutout had 6 drilled holes, 4 line up with the new cutout pattern.

But. .... the Alpha One transom plates can't be used with any engine pre-1983. The rear mount spacing is different. The old spacing is 14", the later 10". I have theorized that a late MC-1 inner plate (1974 to 1982) should fit onto an Alpha Gimbal assembly, but never been in a position to attempt it. The later MC-1 drive will bolt up to an Alpha One gimbal. If you'd like to attempt this 'mix and match', buy the 1978 unit. .. The 1971 inner plate will definitely not fit on the Alpha gimbal housing.

Chris.....

 

[adamjr]

Thank you again. I will likely purchase both. Reason being the later model has a good outdrive and gimbal but a locked motor. The 1971 has a freely spinning motor that needs the fuel pump rebuilt and probably a carb rebuild as well. Much to the disappointment of the admiral I have a penchant for keeping a lot of spare parts. I also am a tinkerer and a former hot rodder so I have some ideas for the locked 165 if it isn't in too bad shape in the cylinder walls. Also thank you for the additional info about the inner plate spacing. The beauty post gutting is I can mix and match and dry fit to my heart's content before drilling a single hole. The information you have shared has been extremely helpful. Now to move things around in the yard for the 71 and find a spot for the 78 to lie in wait. The admiral will let me get away with a second boat on the homestead for a week or two but if I bring two home There might be a fresh mound of disturbed dirt in the back yard.

 

[achris]

.... There might be a fresh mound of disturbed dirt in the back yard.

This does not sound good...

 

[adamjr]

She tolerates a lot...

 

[achris]

She tolerates a lot...

They do, don't they :love_heart:

 

[tank1949]

Thank you again. I will likely purchase both. Reason being the later model has a good outdrive and gimbal but a locked motor. The 1971 has a freely spinning motor that needs the fuel pump rebuilt and probably a carb rebuild as well. Much to the disappointment of the admiral I have a penchant for keeping a lot of spare parts. I also am a tinkerer and a former hot rodder so I have some ideas for the locked 165 if it isn't in too bad shape in the cylinder walls. Also thank you for the additional info about the inner plate spacing. The beauty post gutting is I can mix and match and dry fit to my heart's content before drilling a single hole. The information you have shared has been extremely helpful. Now to move things around in the yard for the 71 and find a spot for the 78 to lie in wait. The admiral will let me get away with a second boat on the homestead for a week or two but if I bring two home There might be a fresh mound of disturbed dirt in the back yard.

When you pull motor and OD, you may find ROT in transom. That will change everything. But, if you already have motor and OD out, it will be less painful.

 

[adamjr]

Hi Tank. Sorry I missed your post earlier. I had a long discussion with the admiral and formulated a new plan. I'm looking at possible hip replacement surgery later this year and we want to make the most of this summer before I get laid up in the fall. Being that the 71 is the easier one to get running (the 78 is locked up) If the transom and stringers are good (new deck is screwed down so easy to access) we are going to use the boat this year and acquire a later transom plate and flywheel cover so the 71 motor can be mounted on the Alpha outdrive. Boating on Saturday and dry dock on Sundays and heavy lifting next spring to move the motor from one boat to the next. I had already planned to replace the transom in my Starcraft with the outdrive changeover. With working on the decks and interior this spring, summer and fall hopefully I can get her completed save for the motor and controls being switched over in the spring.

 

[achris]

Just remembered. The 165 stopped as the MC-1 stopped, so no flywheel housing for the 165 to bolt to an Alpha One transom.... BUT, the flywheel housing for the 140 is the same as the 165, and that engine DID make the change to the narrower rear mounts. So, a later (1983 and on) 140 flywheel housing will bolt up to an earlier 165. You may have to change the couple, or measure the lengths and use the earlier yoke.

From 1983 all yokes are the same length, 9-9/16", but before 1983, the V8s used the 9-9/16" and the in-lines (120, 140, 165, 470 etc) used an 8-1/8" yoke....

This might be helpful in marrying a pre-83 165 to a later inner transom plate.

Chris.......

 

[adamjr]

Thank you again Chris. That was a question I was going to ask. I was doing some research and some searching on fleabay and I found a flywheel cover claiming to be for a 120,140, and a couple of v-8 GM engines. I need to do some narrowing down of part numbers and cross reference to see what Mercruiser says they actually fit to be certain. But the price is somewhere around $50-$60 including shipping which makes it cheaper than buying two donor boats and less of a Frankenswap is always a little easier on the brain. I greatly appreciate your sharing your knowledge with me. It makes the project seem a lot less daunting.

 

[Bondo]

Just remembered. The 165 stopped as the MC-1 stopped, so no flywheel housing for the 165 to bolt to an Alpha One transom.... BUT, the flywheel housing for the 140 is the same as the 165, and that engine DID make the change to the narrower rear mounts. So, a later (1983 and on) 140 flywheel housing will bolt up to an earlier 165. You may have to change the couple, or measure the lengths and use the earlier yoke.

From 1983 all yokes are the same length, 9-9/16", but before 1983, the V8s used the 9-9/16" and the in-lines (120, 140, 165, 470 etc) used an 8-1/8" yoke....

This might be helpful in marrying a pre-83 165 to a later inner transom plate.

Chris.......

Ayuh,.... That's a question I ain't figured out the answer to yet,.....

Where, oh where does the extra 1, 1/2" come from/ go to,..??

I'm guessin' it's in the inner transom plate, or flywheel cover,.... or both,...

I know, post-83, the Alpha 1s, All use the longer drive shaft, 'n the GM In-lines(didn't know the 470 is in this group) with the MC-1 use the shorter drive shaft,...

 

[achris]

Ayuh,.... That's a question I ain't figured out the answer to yet,.....

Where, oh where does the extra 1, 1/2" come from/ go to,..??

I'm guessin' it's in the inner transom plate, or flywheel cover,.... or both,...

I know, post-83, the Alpha 1s, All use the longer drive shaft, 'n the GM In-lines(didn't know the 470 is in this group) with the MC-1 use the shorter drive shaft,...

I haven't figured that one out myself.

Pre 83- If you look at everything, the couplers were basically the same between in-lines and Vs. The inner transom plates are the same, obviously. All I can think of is that the flywheel housings for the in-lines is 1-1/2" 'shorter' than the housings for the Vs... And that got changed in 83....

Maybe... ?????

Chris.........

 

[achris]

...That was a question I was going to ask. I was doing some research and some searching on fleabay and I found a flywheel cover claiming to be for a 120,140, and a couple of v-8 GM engines....

Ask if they are MC-1 covers or Alpha covers. The difference is the rear engine mount spacing. The MC-1 cover have 14" spacing, the Alphas have 10" spacing.



Sorry about the crappy writing.. Had to do it with a mouse. :facepalm:

Oh, and if my premise is right (about the housing length being the changed dimension. See above reply to Bondo. Then you'll need to use a 9-9/16" yoke on a drive for a 165 engine with an 'Alpha' flywheel cover and later inner transom plate...)

Cheers

Chris.....

 

[adamjr]

Bondo and Chris, Thank you for the additional information. I didn't check my email for a few days and I came back to find the rest of this helpful info.

The flywheel cover I mentioned earlier had the 9.5" spacing between the mounting points. I had gone ahead and purchased it and it was on my doorstep yesterday. It definitely will mount up on my Alpha inner transom plate. The couplers for the inline 6 all along, according to Iboats, is a Sierra 18-2171 which is also the coupler for the 120 and 140 HP models.

So it looks like the MC-1 drive will need the 9-9/16" yoke to properly mount up. I'm writing a shopping list for all of the things I am going to need. I had a session of kicking myself the other day. I had a bunch of aluminum parts off of the frozen 470 engine that was in the old Four Winns from which I stripped the Alpha gimbal and transom assembly. I was unsuccessful in attempting to sell it so I threw it in the back of my pickup and sold it for scrap. Among the parts I must have scrapped was the exhaust elbow that attaches to the gimbal housing. I probably got a buck and a half for it and now it's going to cost a bunch to get a second hand unit. That and most of the attachment hardware was just tossed in a bucket and also went to scrap. Lesson learned. Throw away nothing.

This is going to be fun. I have a week of vacation planned in March. I'll need to place my orders so it all arrives while the Admiral is at work. Then when it's time I can retrieve some dusty boxes from the parts shelves in the basement. "New parts, honey? These old things? Nah, a little degreaser and they cleaned up really well."