Mini Mac 30

[How570]

I’m Working on a mini Mac 30 and the clutch drum seems to have more Play than I think it should,The bearing seems ok but is it possible that it is just worn down ,Are The Drum bearings replaceable,It’s A Mculloch 90150 drum,I’m Learning As I Go

 

[MacAttack]

I think the bearing does come out, but I have a few where the drum feels pretty sloppy and it doesn't seem to affect anything.
Unless it's to the point that the bearing needles aren't moving and it's grinding on the crankshaft, I'd just keep it greased and run it. Those clutch bearings don't feel tight unless they're virtually new, in my experience.
You could probably find a bearing or a complete new drum on eBay pretty easily.

 

[How570]

Thanks, I’ll Just Grease It Up And Run It And See

 

[heimannm]

90150 is the cloverleaf style sprocket, that drum should be fit with 91222 drawn cup needle bearing. They to feel sloppy even when everything is new.

215252 is a spur drum and if I remember correctly they use an open needle bearing (67650??) and they do seem to have a little less slop.

Mark

 

[How570]

Thank You For The Information,I’m not Going To Run The saw A lot So I Think I’ll Just Keep The Original Drum On It

 

[How570]

Could any one tell me the carb kit I need for this also ,It Says MDC 9 And 1 so I’m Not Sure Which Kit I Need ,Thanks

 

[heimannm]

You will want to remove the welch plugs and replace the check valve in the MDC, they are notorious for failing on older carburetors.

There are many options for the gaskets & diaphragms, for example:
https://www.ebay.com/itm/1555985846...GTd64lf316hVIKHUp-MFv3v8xLS4PXoMaAnRGEALw_wcB
Kits with the check valve are much harder to find. The check valve kit for the SDC carburetor will work (86-523) but you need to find a 7/16" welch plug as the SDC one only comes with a 5/16" welch plug.

Mark

 

[MacAttack]

Could any one tell me the carb kit I need for this also ,It Says MDC 9 And 1 so I’m Not Sure Which Kit I Need ,Thanks

I'm much less refined when it comes to fixing these saws than Mark haha... I've only replaced one check valve, the other ones I've personally had excellent luck testing the check valve before replacing it.
What I do, with the carb apart but welch plugs still installed, is I remove the high speed carb needle and put a piece of fuel line over the opening, and blow air in and out with my mouth on the fuel line (do NOT use compressed air. If it's working you can blow air into the throttle body but when you try to suck air into the hi speee circuit you should feel the check valve (which is literally just a TINY rubberized fiber disc) snap shut. I have 2 mini macs made in 1972 and 1973 that I tested and both work and run perfectly!
If you want to be thorough definitely follow Mark's directions, if you're a little more risk taking you can try to test it.
However.... the diaphragms and gaskets always need replacing.

 

[How570]

Thanks A lot I Really Appreciate Your Help And Knowledge

 

[MacAttack]

Glad to help, I've revived about 5 of these types of small McCullochs over the past few years, and have gotten to know em pretty well.