Mac 49 help

steveohara · Post by **steveohara** » Mon Feb 07, 2011 1:41 am

Anyone know the numbers stamped on the back of the block for the 49, 49C and 49E? Are they all the same or ???
Anyone know what changed from the original 49 to the 49C?
I also need to know what type of flywheel came on the 49 and 49C... modern version like the 91 and 101 series or the lighter version like the earlier models. How about the rod... slotted or no?
Thanks in advance for any info you guys can provide.
Regards,
Steve O'Hara

Scott Kneisel · Post by **Scott Kneisel** » Mon Feb 07, 2011 11:08 pm

Hi Steve,
Attached is a comparison of a Mac 250 saw block...early version vs late version. The late version is the Mc49 and Mc49C block and the part numbers are stamped on the block as shown. I have only had one 49E block come thru my shop and I don't think it had any numbers on the block, I believe it had a nameplate riveted to the block similar to the Mc92 & 93. Dick Teal has that block now, maybe he could tell you for sure. I know it has radiused head fins that are distinctive from the 49 and 49C. All have a needle bearing PTO.

49 and 49C have a non slotted rod like the Mc8 rod and a 1 3/8" stroke crank with taper PTO, RH threads and a key slot. The 49E has LH threads and no key slot.

Don't know if the 49C or E have 5 degree flywheels but the Mc40 had a standard flywheel.

Also, the Mc49 had a thick ring piston, 49C and E have thin ring pistons

Mac 250 Saw Block Comparison.pdf: (354.1 KiB) Downloaded 946 times

Scott Kneisel · Post by **Scott Kneisel** » Mon Feb 07, 2011 11:11 pm

Correction of typo, Mc49 had a standard flywheel like the Mc8 and most of the chainsaws from that period.

Dick Teal · Post by **Dick Teal** » Tue Feb 08, 2011 9:23 am

Steve,

The 49E I got from Scott has the number plate rivited onto the block. I'm in Florida until mid-March so I can't check if there's a stamped number also; I don't think there is one.

Dick Teal

Scott Kneisel · Post by **Scott Kneisel** » Tue Feb 08, 2011 9:38 pm

Here is a pic of a 49E block. This one has the 3rd port wall removed because it has been modified with boost ports. You can see where the metal tag was riveted on the block and the rounded head fins. It is a distinctive block.

Mc49E Block.jpg: (232.62 KiB) Not downloaded yet

steveohara · Post by **steveohara** » Wed Feb 09, 2011 4:59 am

Thanks for the help guys. I have two here and one matches the pics of the later 250 block and has the same numbers. The other one is a bit different... same shape fins, no numbers stamped on the back , exhaust port gasket surface recessed for the rectangular copper gasket, structural ribs running from base of intake manifold to the bottom of the block like the 91B blocks, threaded insert in the third screw location for the exhaust instead of tapped into the alloy. Shroud says 49C but it has the sloper manifold with the little Walbro carb like the 49E. Do you supppose there was a transitional 49C that came with the smaller intake? Maybe the rules allowed the older engines to be fitted with the smaller carb and intake and still be legal to run in the kid class???
Regards,
Steve O'Hara

John Fields · Post by **John Fields** » Thu Feb 10, 2011 4:06 pm

Steve,
I raced Rookie class using the 49C and 49E's and I don't recall a transitional 49C with the smaller intake / walbro carb. Still going form memory here, but I believe that carb wasn't introduced until the 49E came out. You could run a C carb on an E and visa versa. We ended up putting a C carb on the E motor - like a completely different engine - ran stronger and easier to tune.
John

Scott Kneisel · Post by **Scott Kneisel** » Thu Feb 10, 2011 9:01 pm

Just had a thought, we are forgetting about the Mc49 M/C.

Maybe that block is the same as the 49E but without the curved head fins?? Just wondering but I just looked and the 49M/C IPL shows the same part number for the block as the 49C.

Anybody know what year the Mc49E was produced?

Terry Bentley · Post by **Terry Bentley** » Thu Feb 10, 2011 10:41 pm

Mc49E was introduced in 6/72 and ran thru 6/76. The Mc49 m/c is different from the other models. It has the intake opening like 91 series, no third port induction, and double ball bearing crank.

Scott Kneisel · Post by **Scott Kneisel** » Fri Feb 11, 2011 7:55 am

Wow Terry,
That is incredible!! Totally different from what is in the McCulloch IPL that I have. The IPL also shows a 3/4" straight crank running in a needle bearing and your's is a taper shaft. I guess McCulloch documentation didn't keep up with what they were actually producing.

That crank must be very rare with a 1 3/8" stroke and BB on both sides. I'll bet that block is pretty rare too.
A real keeper.

Mac 49 help

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