1977 mercury 1150 crankcase question

[monk-monk]

How big of a risk would it be to use the crankcase cover from say "engine block A" and bolt that cover on a different block...i know the blocks/crankcases bearing journals are align bored for a matching set...just wondering how critical this is...?

 

[Gomer50]

Re: 1977 mercury 1150 crankcase question

Thats a good question?? I am rebuilding a 1974 85hp mercury and had to use the crank out of a 1972 80hp motor and 3 1978 80hp pistons and also the main bearing from the 1974.I decided to put the crankcase cover from the 80hp on the 74 and everything matched up perfect.I personally could not see or tell any difference between the two.I am by no means a outboard mechanic but it worked for me.

 

[monk-monk]

Re: 1977 mercury 1150 crankcase question

Well, hopefully we can get some more insight about this...thinking on the negative side, if the journals from each half don't line up perfectly, then one could assume that it could crack the crankcase cover when torqued down...or, could it warp the reed blocks or the main bearing blocks...possibly getting something out of center on the entire crankshaft assembly....??

 

[Faztbullet]

Re: 1977 mercury 1150 crankcase question

It been done for years.... lay the front half on block and check that the end cap surfaces are even. If not you can remove the alignment pins from block to get a little give or take. This is what you have to do if using a ADI front on a older block and sometimes you have to machine upper as its to high..

 

[monk-monk]

Re: 1977 mercury 1150 crankcase question

Thanks Faztbullet...the reason i asked is because i have a NOS 1977 1150 block...its brand new but it was dropped and the outer upper starter ear is broken on the crankcase cover...i could have it welded but i see them on ebay for way less money...i have the block up for sale on a popular auction site, but if it doesn't sell then i will just get another cover...and i know exactly what you're saying about the end cap mounting surface needing to be true, and the I.D. of the bearing journals...Thanks!!

 

[daveswaves]

Re: 1977 mercury 1150 crankcase question

It been done for years.... lay the front half on block and check that the end cap surfaces are even. If not you can remove the alignment pins from block to get a little give or take. This is what you have to do if using a ADI front on a older block and sometimes you have to machine upper as its to high..

Also if you are using the older block that uses the captive nuts you will have to install a hex cap bolt from the block side up into the ADI front cover where the starter holder is. The distributor front had the bolt going through the starter support. The adi front cover has the starter mount rotated 90 degrees and there is no through hole. If you leave out this bolt you run the risk of a crankcase air leak.