Need help identifying mercury 22 cu in block

[wyo307]

I am looking at buying a mercury block but would like to know what motor it is before I do. The problem is in its current state there are parts off of multiple motors bolted together so I can’t trust the serial number on the transom clamp. On the block itself I see the numbers 923-1391 and 830-1966. It does have the merc 250 KA15A carb on it. Any help on how to identify if it is a mark 28, merc 200 or merc 250 by just looking at the block would be great. Thank you in advance!

[dave-bernard]

get the serial ######## on the top of the flat on the block by the exhaust

[bobvdinghyracer]

1 way to tell what it is ..black paint, offset plugs = 22ci padded block … , the best of all … going backwards no offset plugs / black block = not padded .. is basicly same as a mk28 or a 250 , those were all white blocks as far as i kno , imo… the 250 was no big deal … little hotter porting but thats it and if ya want the same as that with the others then open up the ex ports … not a big deal ..no real secrets to it (leave the intakes alone )

[daytonajohn]

Internally the reed cage is different. Also the reeds and reed stops not the same as the Mark 28 and Merc 250.,  the KA15A is 1/8 inch bigger to match the double punched 9/16 milling tool exhaust port size. Mercury did all those changes to gain 3 HP

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