1972 Merc 120

[dozerII]

Well I went and did it drove a total of 2745 Kilometers to pick up my new to me boat. 1972 Starcraft 18' SS 120 Mercruiser. The boat and motor are in great shape. Compression is 135,155,155,150. and it runs great, but needs a tune up. The points look real bad and there is green corroision on the cap contacts. so I will replace all these. The question I have is the wire that comes from the neg side of the coil to the distributer is in very bad shape all the insulation is falling off and it is covered with green corrosion everywhere. Is this a special kind of wire (ie Resistance) or can I just fabricate a new one out of the appropriate size wire? I am also trying to find the serial number for the motor and looking where the manual says above the starter but it is not there, anywhere else it may be? I was going to change to the electronic ignition conversion but it it will have to wait till next year $$$ The maunal calls for 20 weight oil for the trim, is there a substitute as I can't but tjis locally?

Thanks Glen

 

[ziggy]

Re: 1972 Merc 120

Is this a special kind of wire (ie Resistance) or can I just fabricate a new one out of the appropriate size wire?

in looking at the wiring schematics, it looks like the ballast resistor is on the positive side of the coil. get service manual #1 and look at the several wiring dia. they have. one is yours.

I am also trying to find the serial number for the motor and looking where the manual says above the starter but it is not there, anywhere else it may be?

not that i'm aware of. to me, that may indicate it's a replacement block if there's no mercruiser tag above the starter.

I was going to change to the electronic ignition conversion but it it will have to wait till next year $$$

imho, save your dollars. points system worked fine in '72, it'll work fine today too. just keep up with the pm.

The maunal calls for 20 weight oil for the trim, is there a substitute as I can't but tjis locally?

10W40?, 30W?, 10W30? motor oil. best i understand, just about any regular ol motor oil. i tried to buy some 20W when i got my rig. everyone laughed at me, said it hadn't been produced in many years. anyways, i can't remember what i got in mine, but one of the above is likely..

 

[dozerII]

Re: 1972 Merc 120

Thanks Ziggy The info ia a big help.
Glen

 

[indy440]

Re: 1972 Merc 120

is there carpet between the front motor mount and the stringer? That looks a little odd...

Put a wrench on those two bolts that hold it to the stringer, I'll bet 10 bucks they just keep spinning and spinning and never tighten...

 

[dozerII]

Re: 1972 Merc 120

Indy440, I am not sure what you are refering to. I have no carpet in the boat.
Glen

 

[indy440]

Re: 1972 Merc 120

Ok, that blue stuff that you can see under the front motor mount I thought was carpet. Is it just blue fiberglass? You can see it under the seat on the right too. It sure looks like carpet.

 

[fishinpa]

Re: 1972 Merc 120

Ok, that blue stuff that you can see under the front motor mount I thought was carpet. Is it just blue fiberglass? You can see it under the seat on the right too. It sure looks like carpet.

Its just floor covering the vinyl type!
typical in the starcrafts
dont know why it would be there though , does look a lil strange in there !


fish

 

[Kainon]

Re: 1972 Merc 120

I use 30w oil in my 74 Starcraft Mercruiser trim, I've also used Compressor Oil too.. Straight 30w non-detergent is what I've used. Dont know why you couldn't use 10w30 or 10w40.

 

[bigskiohio]

Re: 1972 Merc 120

number is obove the starter but higher up if i remember right. below the head

 

[dozerII]

Re: 1972 Merc 120

Indy440, Are you refering to the two bolts on the front motor mount circled in red in the photo? The blue stuff is vinyl, and I'll take you the the $10.00 I just went out and put a wrench on the two bolts and could only turn them about a 1/4 turn till tight. Is this normally something that happens?

I looked again for the serial number and can't find it anywhere above the starter, is it a tag or stamped in the block.

Thanks for the replys, I topped up the trim with a little 10/30.
Glen

 

[indy440]

Re: 1972 Merc 120

I guess I owe you 10 bucks! haha. The reason I said that is orginally I thought someone had layed carpet under those mounts, meaning that it was 1/2 assed, meaning that it probably wasnt taken care of and that stringer would be rotted. But, I was wrong! haha

But now that im looking again, is that even a fiberglass boat or is it aluminum?

 

[bigskiohio]

Re: 1972 Merc 120

you got to stick yoyr head back in there behind valve cover use a mirror

 

[dozerII]

Re: 1972 Merc 120

Indy, The boat is aluminum and it mast have been well taken care of because everything is original and still in pretty good shape for being 38 years old.
Thanks

Bigski, I will try looking behind the head I didn't check there
Thanks
Glen