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I've been doing a chainsaw motor to MC5 look alike conversion, while going through various old photos and talking to others, I realized that the MC5 sidecover varies, I see evidence of 2 different types of sidecovers and 3 different orientations for the MC5 nameplate.

The early sidecovers, seem to have been a direct carry over from the early 1-40, -50, -60 saw motors. They have not flat stop on top like the later covers, the flat spot being where some covers were cut out for a rubber plug boot (for some saw models and later the MC6). It appears there was no single one way the MC5's were produced during their short Feb 1960 to June 1960 production life.

FYI - I'll have a nice write up on my chainsaw conversion, I've taken a 1-51 saw motor, MC6 crank, MC49 piston, a lot of block modification/porting (boost ports too!), sidecover and fan shroud mods ..... mostly starting with a $35 box of parts bought at TBO last year .... it's going to be a really cool looking and running motor. There are rumors of several MC5's coming to TBO this year, if you have one, bring it!

Jeff

Hey, Jeff. The Mc5 on Bill Jefferies' GK 800 looks exactly like the one I had in '60. Mine did not have the boss later used to cutout for the plug cover. See you at Fremont. Ted

If anybody has a good MC-5 number plate, I have a shop that can make nice reproductions. I had him make some MC-10 plates for me.

Terry Sullivan
678.617.0730

Hi Guys

I am also building a Mc 5 but I am starting with a very nice original stock bore and stock port Mc 5 stamped block that came with all my Caretta stuff out of Cart Labs in Gresham Oregon. I have picked up a brand new crank and rod from Zoe and I have a new early Mc 10 wide ring piston that the two motors shared. The head is the same as a Mc 6 and if it has a part number on it the number is zzzz. In all the parts I have I don't have one side plate or fan shroud that is for the Mc 5 so I am also looking at what saw I need to get to scavenge these two parts.

Now I am a bit confused as I just got a Mc 1-50 chain saw thinking it has the correct side cover and fan shroud. Yes the two castings are setup for an outside spark plug with no cutout or rubber boot but the two castings have a large bung sticking out of the side of them. I have not dismantled the saw yet so I am not sure what this odd detail on the two castings is for. No mater what the detail on the castings render them not unusable. So be cautious of a Mc 1-50 chain saw as there may be differences in different serial number machines.

Terry I would also be interested in a Mc 5 decal.

Also the Mc 5 has a 1 3/8 stroke and the Mc 6 is 1 1/2. The blocks are the same between the two motors. The Mc 5 with stock crank rod and piston the piston will be down the bore just a little and on a Mc 6 it will be .031 above the top of the block. Just been thru all this with the Mc 6 that will be on my Caretta at Medford next month. I am as of today assembling the engine.

Turk

I just picked up a MC5 metal plate mac nameplate from ebay seller robbinloois, the originals were printed on a thin metal plate. They have ones for several models, I picked up ones for MC5, 6, 7, 8, and 9, all printed on metal plate. My item came quickly. Contact them, they don't have anything listed now, it will appear below when they do list something ...


Try the early 1-60 saw sidecovers / shroud (1-61 for instance), that is supposed to be identical to the ones used on the early MC5 motors.

Also, the MC49 pistons work in the 1-51 block, even with the MC6 crank, the top ring does not come out of the top of the cylinder, the piston does and you will need the MC5 hop-up head gasket (1/16" thick - 0.064", Perry has them on his website - just ordered a few). Be careful to position the gasket so the piston doesn't hit it!

I'm making a video of the whole 1-51 to MC5 conversion ... I'll have it up in a week or two. Here are some photos in the mean time ... it's a work in progress for the TBO!!!!

Jeff

As to using extra thick head gaskets for your stroked Mc 5 you mite consider doing what I have done to modify the head on my stroked Mc 6 that will be on my Caretta at Medford next month. I built a fixture to machine out a little material from inside the head so I can run a standard head gasket. I did this way back in 1961 when Cart Labs of Gresham Oregon came out with a stroked crank and piston for the Mc 6 that year. Rather than use the Mc6 piston I stared with a 1-72 chain saw head. They look exactly the same but have a little more material on the bottom of them and also a little larger combustion dome. The stock Mc 6 the piston was proud .031 and the new new piston after modifications was proud .075 so I machined .045 out of the head in doing so I keep the same distance from the top of the piston to the head. This machine work also reduced the combustion dome down to the same dimensions as the original Mc 6 head had.

I mentioned a modified piston. Yes one of the things we did that made the Mc 6 and 10 so fast here in Oregon that year was first we did not touch the ports in the cylinder rather we changed the port timing by modifying the piston. Again we kept a flat top piston so as not to disturb the gas flow through the cylinder. By cutting .020 off the top of my Mc 6 piston we gained 4000 rpm and three hp. Confirmed on a dino. We also used a thinner head gasket. When I started building the Mc 6 I am working on I had always wondered just what the machining of the piston did so I first plotted out the port timing with a stock crank and piston using a degree wheel. Then I machined off .020 from the piston and piloted the port timing again. Then as I set up the engine with the stroked crank and new piston I did the same routine again. What I found was really interesting and know know why the motor made so much more HP.
Turk

Jeff,

What would we do without JB-Weld, dremels and files??

I was going to wait for a 1-60 to start with, but since I have a few MC-6's in pieces, I will forge ahead.
If I get brave, I may try modifying the covers with my tig welder.
Thanks for the inspiration!

Terry

here is a photo of a 1-60 saw, the sidecover looks like the early MC5 one, but the fan shroud cover does not look like a kart ones that I have seen.




FYI - for my 1-51 to MC5 conversion - I modified a shroud and sidecover from a kart motor (old used parts that needed a lot of restoration work), I did not use 1-51 parts, I only started with a 1-51 block, not a whole saw motor.

Jeff,

If we could just see the back side of the engine in the first photo you posted ( early dealer photo of MC-5 )!
I'll bet my lunch money it had the same fan cover as the 1-60

Terry

I've seen several very early 5's with the 1-60 style flywheel cover. I'm sure Mac was just like Bug and GoKart; use whatever was overstocked if it'd fit. I'll bet Jeff's will run lots better than mine did. I took it out to the old 1/10 mile Q.M. track in Melbourne, FL on dad's new Wasp, and one of my old rivals was there with his brand new Wasp with a very early AH-58 PP and 13" rear tires. He cleaned my clock! Dad made some calls to McCulloch and came up with a prototype Mc6 crank, plug cover and thin ring piston. At least I whipped up on Mark Allen next time we met! TJ