Mac Chainsaw Block VS Kart Block

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Dennis Detweiler
Posts: 65
Joined: Wed Nov 14, 2007 9:35 pm
Vintage Karting items owned: 1961 Simplex
1974 Margay Concept Sprint
1984 Margay SR-16
Mc91b1
Location: Iowa

Mac Chainsaw Block VS Kart Block

Post by Dennis Detweiler » Wed Nov 28, 2007 6:28 pm

Is the Mac chainsaw block and the Mac kart engine block cast the same?

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steveohara
Posts: 411
Joined: Thu Jul 19, 2007 2:29 am
Vintage Karting items owned: 1969 Bug Sprint Mc 91B1
1965 Dart Gran Prix twin Mc100s
1963 Bug Scorpion ESll Mc45

Re: Mac Chainsaw Block VS Kart Block

Post by steveohara » Wed Nov 28, 2007 11:16 pm

Some are the same and some aren't. Most of the saw blocks are very similar to the Mac 49 but they use a different bearing on the crank on the PTO side. Blocks made for the "Super Series" shrouds (like the Mac20..101) have shorter coil posts and the upper coil support is shorter or removed completely. Saw blocks usually have an extra hole in the bottom surface where the stuffer mounts... it is for the chain oil trigger rod. Another variation I have seen in some blocks with integral heads is the wide shallow combustion chamber with the spark plug moved closer to the center.
I'm sure there are other differences that I'm forgetting but it is fair to say that all of the blocks are very similar.
Steve O'Hara

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