Mc5 & 6 ?????

Rick Chapman · Post by **Rick Chapman** » Wed Oct 08, 2008 9:05 pm

I just bought an engine that is suppose to be a Mc6, but on the back it is stamped "Mc5&6".
Does anyone else have a block like this or know anything about this. It looks like the factory paint is covering the stamped letters and numbers.
Thanks
Rick Chapman
Rixkart@aol.com

Tom Smith · Post by **Tom Smith** » Wed Oct 08, 2008 11:53 pm

Mc-6.JPG: (391.55 KiB) Downloaded 103 times

Tom Smith · Post by **Tom Smith** » Thu Oct 09, 2008 5:23 am

Early Mc-6s were assembled from left over Mc-5 parts. Without paint you can see the small x stamped on top of the 5. Basically the 6 is a revised 5 with some different parts. Mcculloch made a slight blunder with the Mc-6 because it out performed their more expensive super class Mc-10. Then they had to make stroker kits for the Mc-10s to keep them selling. One of the detail changes they had to make to the Mc-10 stroker rod was move the rod bolts closer together to clear the block. Those bolt centers have been used for every mac kart motor and big saw rod built since the stroker Mc-10.

Rick Chapman · Post by **Rick Chapman** » Thu Oct 09, 2008 7:50 pm

So Tom,
If the Mc5-6 would be an early Mc6, which carb came on it?? Tillotson or flat back?? And when did McCulloch go to the flat back carb. This question came up a couple of months ago and now I am not sure which carb to use on this Mc6 or the other 6 I have already restored..
Thanks
Rick
Rixkart@aol.com

Tom Smith · Post by **Tom Smith** » Thu Oct 09, 2008 10:17 pm

Mcculloch Tillotson table only shows that the first 6000 Mc-5s came with HL63BX carbs and Mc5&6s 6001 and up (early Mc-6s) came with HL93A carbs. As to when Mc-6s switched to flat backs my guess is that it was early. I have some 9 ported Mc-6s with flat backs in boxes somewhere but I don't know what their serial #s are without digging them out.

Rick Chapman · Post by **Rick Chapman** » Fri Oct 10, 2008 6:17 pm

Thanks for the info. I guiess I will have to channge my 2 Mc6's carbs around..
All the information was really appreciated....
Rick

Tom Smith · Post by **Tom Smith** » Fri Oct 10, 2008 11:08 pm

I took a look at another Mc-6 block that has Mc-5 stamped out with an x. Mc-6 is stamped on the oiler boss. Serial # 6918. Hope this ads to the early Mc-5&6 confusion some more. This one was a 9 ported Mc-6 that was on a mini-bike my buddies had in high-school and they found it in their mothers attic.

Dominic Salvato · Post by **Dominic Salvato** » Mon Oct 13, 2008 6:49 pm

Ronald Cubel · Post by **Ronald Cubel** » Mon Oct 13, 2008 8:05 pm

No Mc10 , racers would switch to Mc10 Carb to increase preformance...ron

Dominic Salvato · Post by **Dominic Salvato** » Mon Oct 13, 2008 8:13 pm

Your right......

Mc5 & 6 ?????

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