McCulloch Chain Saws

[rwoods]

I keep my saws preserved with a coating of mix, sawdust and bar oil. Amazing how nice the paint looks under a 1/4" of oily sawdust. Ron

 

[svk]

I'm trying to figure out why there are such differences in paint condition on older Mac saws. Occasionally you see a saw like fossil's PM700, which happens to be what my dad's old 10-10S looks like (which I have now). I know that 10-10S got lots & lots of use, but was relatively well cared for. i.e. It didn't roll around in the back of a pickup truck or anything. But more often I find them looking like mopar's 5-10E, which is with lots of random paint flaking off all over. I've picked up a PM700, 10-10A, and a 805 that all look tough. I can't believe THAT many saws were thrown around or left to roll around the back of a truck all their life that they would end up like that. Besides, the paint flaking is all over, not just on the edges that would hit when rolling around. Is it just from some difference in paint quality over the years or something? The old 10-10S is from 1982, and the PM700 above looks to be from about the same time period based on its style. Did Mac improve their paint quality in the 80's compared to what it used to be before that?

Rob

I would say where it's stored makes a big difference.

On the floor will invite rust and corrosion. Up on a shelf will keep a saw in much better shape.

 

[happysaws]

I've got a Mac SP125, and the decompression valve leaks while the saw is running. Does anybody know where to get a replacement, or if a Stihl or Husky decompression valve will fit?
Thanks much!

 

[heimannm]

Check closely to see exactly where it is leaking. There is supposed to be a copper gasket to help it seal where the base contacts the head. The other possibility is that the poppet and seat are loaded with carbon; there is a post in this thread somewhere demonstrating a way to polish up the poppet and seat if you can find it. I have had success with some fine valve lapping compound or even toothpaste and lapping the parts until they seal again.'

Part number is 85148, try Bob Johnson (Bob's Lawnmower, Maryland, NY).

The threads are 3/8-24 so the Stihl and Husqvarna parts won't interchange but there were a lot of saws with the imperial thread so you should have little trouble finding one if needed.

Mark

 

[brandonstc6]

@heimannm I need some over in my mcculloch pro Mac 700 build thread. I would really appreciate your expertise on my crankshaft problem.
Thanks
Brandon


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[happysaws]

Check closely to see exactly where it is leaking. There is supposed to be a copper gasket to help it seal where the base contacts the head. The other possibility is that the poppet and seat are loaded with carbon; there is a post in this thread somewhere demonstrating a way to polish up the poppet and seat if you can find it. I have had success with some fine valve lapping compound or even toothpaste and lapping the parts until they seal again.'

Part number is 85148, try Bob Johnson (Bob's Lawnmower, Maryland, NY).

The threads are 3/8-24 so the Stihl and Husqvarna parts won't interchange but there were a lot of saws with the imperial thread so you should have little trouble finding one if needed.

Mark

I removed the valve and cleaned the carbon; it still leaks. When pulling the saw over slowly, The decompression valve closes while the piston is moving towards TDC, and then the valve opens when the piston makes its backstroke.

The valve seems very sloppy, and it opens and closes very easily...

 

[heimannm]

That sounds like the springs on the valve are shot and won't hold it closed, better look for another.

Mark

 

[happysaws]

Will a compression release valve off of a PM700, PM850 or similar saw work on the SP125?

 

[heimannm]

Yes but, they lack the longer knob or handle so they are hard to reach down in the shroud. I believe there were some on the 600 Series saws that also had a longer knob but I don't know if the reach is the same.

Mark

 

[brandonstc6]

I've got a Mac SP125, and the decompression valve leaks while the saw is running. Does anybody know where to get a replacement, or if a Stihl or Husky decompression valve will fit?
Thanks much!

You have a sp125. I still hope to find one some day. The biggest Mac I have is a super 250. Congrats on finding a sp125.


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[happysaws]

Yes but, they lack the longer knob or handle so they are hard to reach down in the shroud. I believe there were some on the 600 Series saws that also had a longer knob but I don't know if the reach is the same.

Mark

I just found a compression release valve on eBay that's for a Stihl TS420 cutoff saw. Has 3/8" threads, but the threads are a lot shorter than the threads on the McCulloch valve. It also has the longer 'knob'. Do you think this will work?

Thanks for all of your help!

 

[PogoInTheWoods]

I just found a compression release valve on eBay that's for a Stihl TS420 cutoff saw.....
Do you think this will work?

If you want to be struck by lightning.

 

[happysaws]

If you want to be struck by lightning.

Ya, I guess I'll just hunt out the original McCulloch part and not take my chances... was only trying to save some time...

 

[ML12]

Finished off my Mac 55, new rings, and seals, the bearings were all like brand new. The motor had zero build up and still had the cross hatching in the bore. Pulls 160psi, still needs quite a bit of run time to break in the rings. Repaired the cracked flywheel cover, and repainted the fuel tank, rear cylinder shroud and the flywheel cover with sunburst yellow and fuel proof clear. I re-installed the governor and adjusted it but still need to tune it in wood. The governor seems to seriously hamper the saws performance though.

 

[svk]

Finished off my Mac 55, new rings, and seals, the bearings were all like brand new. The motor had zero build up and still had the cross hatching in the bore. Pulls 160psi, still needs quite a bit of run time to break in the rings. Repaired the cracked flywheel cover, and repainted the fuel tank, rear cylinder shroud and the flywheel cover with sunburst yellow and fuel proof clear. I re-installed the governor and adjusted it but still need to tune it in wood. The governor seems to seriously hamper the saws performance though.

View attachment 543023


View attachment 543024

That looks great. Nice work!

Mark will have an idea of how to figure out the governor. I was at his place last spring and IIRC he had just fixed a saw that was having problems with one. I don't recall what he did.

What brand of clear coat did you use?

 

[PogoInTheWoods]

Ya, I guess I'll just hunt out the original McCulloch part and not take my chances...

It'll be a much happier saw that way.

 

[ML12]

Mark will have an idea of how to figure out the governor. I was at his place last spring and IIRC he had just fixed a saw that was having problems with one. I don't recall what he did.

What brand of clear coat did you use

Its just not adjusted right I think. should be easy to set with a bar/chain in wood. I had it completely bypassed before and it screamed.

The clear coat is Plastikote Engine Enamel. it says its fuel resistant, but I find the trick is to let it dry for a long long time (like a month or two or just bake it) before using the saw. If you pour fuel on it when its fresh it comes right off like any other paint.

 

[Dennis Gauge]

If you had room for two saws, which of the three would you choose?

1. PM610
2. 10-10 Automatic
3. ProMac 10-10

I'm forcing myself through CAD detox. Already sold 8 saws this fall. Trying to cut it down to one utility/truck saw and a backup. Then I'm going to take some of the proceeds from the sell-off and buy a modern 60-70cc saw for firewood.

 

[PogoInTheWoods]

The 10-10's.

 

[sawfun]

Yeah, what he said, 10-10's all the way.