2-cyl Merc block mark'ns?

[STEVE FRENCH]

http://cgi.ebay.com/ebaymotors/Mercu...QQcmdZViewItem

What was special about the X-O blocks?
Any other mark'ns and or serial numbers Kg-4/Mark-15..(505 etc)...20H........that were prefered?

Can't be that "top-secret" today.....can it?.....
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[G Stillwill]

Steve there is nothing special about a block with that stamped on the top, I have alot of them with that marking. It must be some kind of factory marking to quickly id a block. That block looks like the early 44xxxxx series rat hole port block.

[Graham]

Steve: My best A motor's block S/N was 594987 which had "tilted ports". I was told back then that these were of some value towards overall performance. Yet when Roy Minor looked at the engine after I had one a race he said "nice block but that crankcase should'nt run that good". So much for combinations - hey.

Sincerely,
Don Graham

[oldracer]

2 Cyl Merc Block

Looks like something got loose in the top cyl and did a number at the head.
Ye Olde Desert Geezer Al

[snyder]

Blocks beginning with 595XXX (tight cc's) were the prefered of the day and light rods with a sandcast (tight) C'case. I think that a 400XXX series was a good number also.

[lcp8410]

snyder, send u a pm