Mercruiser 120/140

[Star64]

Ok I have what I believe to be the 1967 merc 120/140 stern drive on a 1964 starcraft the transom plate says mc1 and the serial number is worn off the upper unit and none on the inside of the transom so at some point in its life it was upgraded it's only a 110 horse iron Duke parts are difficult to find for this unit and was told that an easy shift of the same era will work and is somewhat of an upgrade but will need to elongate the upper mounting holes on the upper unit is this a true fact and are the parts any easier to get my lower unit drive shaft has the 8 splines and pre load pin my upper drive shaft has 15 splines with a nut over the small bearing any info would be great

 

[Scott Danforth]

first, welcome aboard

second the 120hp unit you have is a Chevrolet 153 cubic inch motor originally from the Nova II. the Iron Duke is a pontiac 151 cubic inch motor which is half the 302cubic inch V8 and has never ever been in a boat. it shares nothing except the same threads in the valve cover bolts.

the 120 or 140 designation comes from the hp output the 120 was a 2.5 liter, the 140 was a 3.0 liter. if you have a 110, then you have a 110 hp version

so specifically what are you looking for? motor parts or MC 1 drive parts?

 

[Star64]

Ok I didn't realize that the 120/140 this the outdrive the engine is a 110 gm were wanting to up grade the outdrive I was told an easy shift will fit by simply elongating the upper unit top holes

 

[kenny nunez]

If you just have power tilt with 1 hydraulic hose on the rams then you will need to swap the setting pin latch along with the spiral shaped bronze shift lever along with elongating the mounting holes. If you have power trim with 4 hydraulic hoses you are in luck and just have to elongate the holes mentioned.
try to post a picture.

 

[Bondo]

wanting to up grade the outdrive I was told an easy shift will fit by simply elongating the upper unit top holes

Ayuh,...... The easy-shift is as common as hen's teeth,......

The later MC-1s are a dime a dozen,....... go with the MC-1,.....

 

[Star64]

One hose power tilt only

 

[Star64]

So if the easy shift is as common as hens teeth I'm gonna guess it's rare the upper and lower I have says 120/140 on the outside and is a different year than the boat I think the drive is from 1967 has the 8 spline lower shaft with preload pin and 15 spline upper drive shaft with the nut above the small bearing a plastic water pump base and aluminum upper water pump housing

 

[Star64]

At this point I just wanna find some thing I can get parts for that will bolt up with little mods

 

[kenny nunez]

I believe after 69-70 is when the drive shaft splines were changed to the finer count. Some of those models still had the hole in the case for the setting pin latch. It will work without the latch but the drive will lift up in reverse in case the drive you end up with does not have the hole.
The holes and the thrust pads on the replacement drive need to be worked on to fit also.
It has been over 30 years since I had one of those models like you have at my shop an this is about all I can remember.

 

[Star64]

Bonds mentioned that the mc1 in the later years are everywhere are parts easy to get and is the unit I have an mc1?

 

[Star64]

I'm trying to post pic but it says size is to big

 

[Bondo]

Bonds mentioned that the mc1 in the later years are everywhere are parts easy to get and is the unit I have an mc1?

1964 starcraft the transom plate says mc1

Ayuh,..... It should be,.....

 

[Star64]

Is it possible to convert any of this to the alpha era

 

[Star64]

Bonds the transom plate says mc1 your correct but its white in color and my exterior parts are black and I believe the outdrive to be from 1967 by trying to look up parts and the boat is a 1964 with 110 hp engine . So my question is did someone replace the original with the 120/140 that is on it now if so I guess then it's a mc1?

 

[Star64]

Sorry bondo not bonds

 

[Bondo]

Ayuh,..... The 120/ 140 denotes the gear ratio, not the drive model/ type,......

My Best Guess is,.... A later model MC-1, for a 120 hp/ 140 hp, which is the 1.98:1 gear ratio, will bolt right on, 'n run just fine,.....

You should be able to find one, used, for under $500........

'n the early '60s Mercs were white, before Merc went all black,....

 

[Star64]

Would I be correct in saying that any mc1 will bolt up to what i have upp till the r was produced

 

[Scott Danforth]

here is my recommendation. look for a mid-90's bayliner with a rotten hull and a 3.0/alpha combination. will be on craigslist as trailer......comes with free boat.

buy the whole boat for $300, pull the working 3.0 and A1/G2 combo out and drop into your hull. then scrap the bayliner (about $100) and sell the trailer for $400.

will require you to drill a few extra holes