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Who can tell me the difference between the Mc5 and the Mc49 crankshafts? Thanks! Ted

i'd like to know myself since they seem to be the same to me.
i know all the saw cranks went over to ball bearings shortly after the mc5 was replaced.
maybe mcculloch had a big backstock of them and promoted the mc49 class as a way to sell off the overage?
dave

Here on the site, the IPL sheets for the Mc49C are missing the key sheet that actually shows the P/N. I assume that the Mc49M/C has a straight crank like some of its larger cousins, so that P/N wouldn't be the same as for the Mc49C.

hi Ted,
i think you're right as i have a 3/4 shaft mcculloch crank that i can't identify.
never bothered to check it's stroke maybe when i get a spare minute.ha ha ha ha ha.

dave

The Mc 5 crank has longer keyways cut like all of the early motors thru Mc 7 or Mc 8. The Mc 49 should have shorter key like 90 series. The Mc49MC replacement crank has ball bearings on both sides. The 1-60 series of chainsaws is correct for Mc5 and directy interchangable for 49c/e.

Thanks, Terry. The longer keyways shouldn't matter. I actually have an Mc6 here that belongs to a buddy of mine. It has a 1-3/8" crank in it for some reason. I may try to buy it from him if it looks good when I get the engine apart. TJ

I have an original Mc5 crank Mac # 50756. It has very narrow counter weights and the larger key slot.

I have had both the 49 M/C crank with the 3/4" PTO shaft #89139 and a 49C crank in the past and from what I recall is that they both had larger counterweights than the Mc5 and the taper pto did have the smaller key slot.

I think the 49C used the same crank that was used in the Mac 640 chainsaw but I have no documentation saying so. That crank was P/N 50756A which is a revision level higher from the Mc5 crank.

The 49E crank is P/N 90891 which has a LH pto thread and no key slot. That is the crank to get!! If you can find one...these "Mc49 class racers" are gulping all of them up!!

All were 1.375" stroke.

I predict that the Mc49 may be the most desired engine this year and probably the most expensive.

Personally I think we should start and Mc5 & 6 class....What do you think about that?

I'm out,
Scott

yay, let's do an open mc 5 and 6 class.
that would be a blast and might have some interesting motors being built!!
dave

Come to the Land of Lincoln Vintage Event at Springfield Il on May 27 and 28,2011 and run the Mac 49 class. This will be our 3 RD YEAR running the mac 49 er by themselves. Very good class and they have a ball. Consider adding it to your event. Come join us for a fun filled Memorial Day Weekend Event
Paul Booth Land of Lincoln promoter

Good info on those cranks, thanks, guys. I'm down for the Mc5/6 class. Just remember, a thin ring Mc6 will eat a thick ring Mc5 for lunch! The displacement difference seems to mean less than the compression ratio, carb and thin ring difference. We had an Mc5 back then with a thin ring piston and a compression boost and an HL93 carb that won lots of junior class races against all comers.