have i id'd these engines correctly?

[Tom Smith]

more Mc-10 dodo if you guys are that interested about them. Fan housing, cylinder head, and cylinder head shrouds are D-44 saw powerhead componets. Mc-10 coil is also from the D-44 saw powerhead. It does not have a bullet connector terminal directly on the coil assm. the conection split is in the wire coming from the point box, inside the Belden plastic sheath that protects this wire which is sodered to the coil. The spark plug lead is also longer which is needed to reach the plug because the plug is not canted towards the coil on these engines.
Early Mc-10s had thick piston rings, not pinned.
Later Mc-10s came with thin ring pistons.
They have about a 1/4" smaller stuffer opening in the base of the crankcase than the later kart motors have and the casting at the base is thinner and weaker since all it had to do on a saw was hold the chain oil tank, not hold itself onto something crashing over curbs, other karts, legs, etc. The intake area is also smaller than the later kart motors have and requires the smaller intake manifold gasket.
Mc-10s also came with two styles of carbs with non interchangeable needles between the two carbs, The needles had different lengths and one had a 16 degree taper and the other one has an 18 degree taper. Hard to see a 2 degree difference on a hi speed needle I'd bet.
One thing they have in common with the other kart motors are the same damn 24 needle rollers that seem to drop into a bottom transfer port or under the wrist pin almost everytime you drop one. By the way the plugs for the bottom transfer ports are the flat style not the cupped style like later kart motors use.
They had two sizes of woodruff keys, larger one is the flywheel key, later Macs used two of the same size keys.
Head gaskets were soft aluminum, rods and rod bolts were about worthless and are the main reason there are not too many strong running Mc-10s left.

[John Tzortzoudakis]

Tom,

We need more dodo on mc10 blocks. What block can be used as a replacement?
I've heard the 1-70 block is the one to use. Is that true?
What other blocks will fit with D44 Shrouds; How about a 1-72 , or a 1-76 or 1-86 to give you 6.04 CI while still looking like an MC10. In my case I am not looking for an official MC10 block as they are too rare and expensive.
Will using a block other than a 1-70 work or will the d44 shrouds not fit considerng using the D44 center plug head?
Another question; Did all mc10s come with a nameplate on the head shroud? I have owned several 10s but don't recall ever seeing a name plate on the cover; maybe the previous owners removed them or they were replacement head covers or the some production runs didn't come with them.

Also were did the MC5 flywheel cover come from if you happen to know. There are several saws with the side cover without the plug cover but how about the flywheel cover? Seems that all of the ones without a plug cutout have a hump for a top mounted starter recoil.

[Tom Smith]

John, the correct block for the MC-10 is a1-70/1-80 powerhead. 1-70s are direct drive and 1-80s are gear drive.
The 1-70/80 was the last model produced that used pushrod operated points.
The other two most similar powerheads are the Super 44A and the Super 55A.
According to Jim Yamane his first dual engine rig was powered by Super 55As. Later he used Mc-10s when he became the first World Champion Karter at Nassau.
As for the later blocks, 1-71 1-72 etc. they have the larger od PTO bearing ala Mc-20, 30, 40, etc. but will work. Remember also that those powerheads did not have the pushrod operated points so the crankshafts are different.
The D-44/M55 fan housing and shroud interchange with a number of saws such as the Super44, Super 44A, Super 55A and some others.
All the Mc-10s I've seen came with the tag riveted to the head shroud originally. Many of the Mc-10 shrouds were cut for header clearence which elimanted the tag. I just had to cut up 3 of them myself a while back.
Mcculloch called the flywheel cover a "fan housing" and the Mc-5 fan housing appears to have been used on a 1-40, 1-50, and 1-60 saw.
There are other items unique to the Mc-10 kart motors, one is the number of different styles of point pushrods they used. Maverick spark was common on Mc-10s. Tom