The unofficial Mac 10-10 thread

[heimannm]

What piston/cylinders (larger) fit onto the 10-10 frame? Just wondering, if I where needing to replace the p/c on mine. Stroke difference?

Any of the 4-10, 5-10, 6-10, or 7-10 engines will drop in a 10-10 chassis, all are 70 cc. The PM700 will fit as well, also 70 cc. All of the 82cc models have a much better anti-vibe mount set up and will not fit the 10-10 frame easily.

Mark

 

[2broke2ride]

How's everyone doing? New guy here, my father just gave me his Mac. 10-10 that he's owned since new right around 1970 or so. It's a left hand start model with no chain brake and a black top if that narrows it down at all. Anyway, it has a problem, when it gets hot if you shut it off you have to let it sit for about an hour or it will not restart. I don't care what you do, clean the plug, change the plug, choke it, hold it wide open, whatever it will not even try to start. It starts second pull every time cold and runs like a scalded dog. Dad said it's had this problem as long as he can remember which is a long time. He said he would just fuel up with it running or take a lunch brake when he ran out. The saw has cut literally thousands of cords of firewood and board feet of logs and I would like to keep putting it through it's paces, any help is appreciated.


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[heimannm]

Sounds like a vapor lock problem, make sure the fuel tank vent is sound and will hold pressure. If not, the fuel boils and you can't move vapor through the fuel pump.

Mark

 

[dynodave]

Just curious if this saw is points/flywheel magneto? My pro mac 10-10 is electronic ignition....However on most of my old saws are points/flywheel mag. I can say in my old british bikes with mags, that a bad cap can strand you when you shut it off after a hard hot run. Kick kick kick no run......Then the next day( after cooling off) all is forgiven and it fires up first kick. New (good) capacitors immediately stop this.

In checking my Homelites, I found the capacitors severly compromised. In fact NONE of them had a good cap. Yet they would start and run. This is typical of a slow condenser (capacitor) death. They should stand up to at least 400volts DC with NO leakage current. I have the equipment to test them.

 

[2broke2ride]

Sounds like a vapor lock problem, make sure the fuel tank vent is sound and will hold pressure. If not, the fuel boils and you can't move vapor through the fuel pump.

Mark

This sounds like we could be on to something, so you're saying the vent in the cap should be a one way valve? It should let air in but also allow pressure to build in the tank.... Is this correct?


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[2broke2ride]

Just curious if this saw is points/flywheel magneto? My pro mac 10-10 is electronic ignition....However on most of my old saws are points/flywheel mag. I can say in my old british bikes with mags, that a bad cap can strand you when you shut it off after a hard hot run. Kick kick kick no run......Then the next day( after cooling off) all is forgiven and it fires up first kick. New (good) capacitors immediately stop this.

In checking my Homelites, I found the capacitors severly compromised. In fact NONE of them had a good cap. Yet they would start and run. This is typical of a slow condenser (capacitor) death. They should stand up to at least 400volts DC with NO leakage current. I have the equipment to test them.

My father always thought it was something to do with the points and or condensor, my only hung up with that is that it will run and run and run as long as you don't shut it off.


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[dynodave]

My father always thought it was something to do with the points and or condensor, my only hung up with that is that it will run and run and run as long as you don't shut it off.


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IF a mag gets started it's spark voltage is up there and keeps going, even if the cap gets hot and performance decreases.
Now you shut it off with a HOT cap which is now even more...under performing! Do you realize how fast you have to pull the string to get enough voltage to spark? Of course it won't restart though it just ran (at 3000 RPM idle). The higher the speed the more voltage it makes.
Close the spark plug gap closer to .010 or .008 and see what happens.
Been there... done that. If it starts then changing the cap is worth trying. Worked on my 61 BSA and 63 Norton...

 

[2broke2ride]

Anybody have the chain specs for these saws? Dads saw has a 16" mcculloch bar but the chain is MIA. Wondering what I need, is it 3/8"pitch? Is there an off the shelf "big box store" chain that will fit? Thanks.


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[2broke2ride]

IF a mag gets started it's spark voltage is up there and keeps going, even if the cap gets hot and performance decreases.
Now you shut it off with a HOT cap which is now even more...under performing! Do you realize how fast you have to pull the string to get enough voltage to spark? Of course it won't restart though it just ran (at 3000 RPM idle). The higher the speed the more voltage it makes.
Close the spark plug gap closer to .010 or .008 and see what happens.
Been there... done that. If it starts then changing the cap is worth trying. Worked on my 61 BSA and 63 Norton...

Thanks, I'll definitely be checking into that.


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[heimannm]

The tank vent should indeed allow air in, then hold pressure up to 5 PSI.

Regarding 10-10 chain, you have to be very careful as a number of saws were built with a McCulloch unique .354 chain rather than standard 3/8". If your saw has a 16" bar, the standard count for 3/8" chain would be 60 drive links, but the .354 would be 61; very difficult to tell the two apart unless you lay them out one on top of the other. Check the drive sprocket to see if it gives you any indication of the chain pitch. If it is replaceable just put on a new 3/8" sprocket and 60 DL chain assuming the sprocket in the nose matches. I do have a couple of .354 sprocket nose bar tips so they were out there.

Mark

 

[2broke2ride]

Little update on the hot start problem........ I ran her hard yesterday for about an hour, **** it off to move some brush, and no start. I hooked up my spark tester that I had in my pocket for just this reason and found good spark. I tried choking it, holding it wide open, everything, no pop, sputter, fart, or any attempt at starting. Took off the air filter and dribbled a little gas down the carb and three pulls later she was back in business so I know it's a fuel problem. The tank vent is MIA in fact it dribbles gas when you lay her on her side to cut a tree. I'm just having trouble swallowing a $26 dollar nos gas cap especially when I don't really understand how that could be causing it, what do you guys think?


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[2broke2ride]

I got the chain, it was standard 3/8 .050 with 60 drivers.


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[heimannm]

If you can't hold pressure in the tank the fuel is more likely to boil leading to vapor lock.

You can replace the duck bill valve in the fuel cap for less than $5, no time to post it all here right now but search a bit and you should find some posts on 10 Series fuel cap repairs, may be in the McCulloch thread.

Mark

 

[2broke2ride]

I went ahead and ordered the cap, dad said he'd foot the bill if it has a chance of fixing this damn hot start problem. If this doesn't fix it what would be the next logical step? Carb rebuild?


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[Tom Hoffman]

I have an older mac 10-10 with the pull start on the right side. all black bae cover, no brake, manual oiler only i think

Can anyone help me with a question I have on this.
Some models have right hand pull start. Why is that? Is it a commercial or homeowner feature? I just picked one up, runs great and cuts fast. Solid saw. I just can't figure that out.

 

[workshop]

McCulloch did a TON of things different and sometimes I think they did it JUST to be different. Nothing wrong with that.

 

[Tom Hoffman]

McCulloch did a TON of things different and sometimes I think they did it JUST to be different. Nothing wrong with that.

Thank you.
My first saw 25 years ago was a mini Mac 14. So I started collecting macs. Trying to find out every little detail about them.

Here's the newest one.

 

[SteveinUT]

What kind of RPMs do you guys recommend for a properly tuned 10-10A? I have pretty bad hearing (20 years in the military) and I am having a tough time fine tuning my 13-prefix 10-10A by ear.

 

[Mac 6-10]

I don't have a tach. The McCulloch manual states to adjust the high needle for best cutting performance.

 

[SteveinUT]

Thanks Mac- I think I have it pretty close. My hearing is so bad that my left ear is pretty much gone, and with the tinnitus in the mix as well, I'm just paranoid about burning it up. If anything, I think I have it a little rich on the H setting, which is better than too lean. I ran it WO and then backed it off til it started 4-stroking, and it seems to be performing pretty good in wood. I was just hoping there'd be a specific RPM that it should run at so I could fine tune it, if needed. I don't cut much with it, but it's a loaner for when we manage to sucker family into helping cut firewood.