Mac saw block ID

[lemtracy]

Found this fixed square head Mac saw block in my stash of old parts and was wondering if anybody could identify what it is, it does have 6 intake ports and has at least 2 but could be 3 boost ports opposite the exhaust and 3 exhaust ports, I haven't pulled the crank or piston yet but going thru the intake port the bore is close to 2.165.

Thanks
Larry

[Brian Santee]

Best way to I'd a saw block is markings opposite of the intake just above the bottom of the block. Should be stamped in.

[Terry Bentley]

I know this thread is a over a year old, but the information is still useful.

There are only a couple of possibilities if bore is 2.165". But looks to be one in particular. First this is a very late model block because it has the recessed exhaust gasket. That was was the last variation.

If the block is stamped on left side when turned upside down, the number might be either 68529 or 61406.

It is likely the latest model Super 550 and is 100cc's. An excellent find. If block is stamped will be 68529.
Another less likely possibility would be a model 450. This one is an oddball. It has a 1.500" stroke but has 2.165 bore. It is the only model I am aware of with this combination. Both of these should have ball bearings on both sides of crank, and also tapered pto.

There is always the possibility this block has been bored 0.040" oversize. But being a fixed head model not very likely.