McCulloch Chain Saws

[fossil]

Thats just it, im not sure how to set the metering lever on these so I just left it alone. It runs worse than before I touched it lol

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Some info in the attached on the flatback maintenance and settings.

 

[svk]

I believe there's photos in here where one of the gurus (probably Mark) showed it step by step.

 

[2broke2ride]

Old Chainsaws $65
http://albany.craigslist.org/grd/6040990134.html

via cPro for Craigslist
iOS: http://tinyurl.com/cPro-iDevice
Android: http://tinyurl.com/CL-Android
Thinking of buying these, mostly for the Mac as it would be my first six cube saw. What do you guys think? Are they worth a 3 hour drive? Or is someone local that could make the deal and ship to me?

 

[heimannm]

$65 for a 550 seems to be a good deal but you don't know what has been done to it. That red knob on the side of the AF cover is definitely not stock.



Mark

 

[brandonstc6]

I asked for help several weeks ago about vacuum testing a pro Mac 700. Work has been slow on the saw, because I have school during the week. I replaced the missing dsp cleanout screw and the saw was still leaking. I found out that the insulator was broke between the tank and the cylinder. I ordered a new one. When I took the tank off, the plastic insulator fell apart and the pieces went into the cylinder. So I took the saw completely apart and cleaned everything. I re-sealed the cylinder base with motoseal and applied a thin layer to the bearing pockets. After sitting overnight, I re-pressure tested and it failed. I sprayed soapy water all over and I couldn't find the leak. I used gasket material under the muffler and my block off plate. The only place in didn't really get much soapy water on was the muffler block off gasket because it was between two fins. I am going to try replacing the gasket material with rubber under the muffler. Is there anything else I should try?
Thanks


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[heimannm]

I made some plates to block off the intake and exhaust when testing saws, rubber blanking gaskets are pretty handy here.

Gorilla tape will also work for vacuum testing but you need something more for the pressure test.

Mark

 

[Brian Thacker]

Oil Pump. I have had those leak before.

Mark:
Nice find. I know what you mean about not knowing what has been done to it. I got a what was a nice looking Pro 10-10. I have gotten into a habit of just replacing the crank seals, rebuilding the carb and replacing the fuel line and vacuum lines on a saw before I even try to start it, most of the time. I tore this one down to find the oil tank had been broken and someone had tried to fix it and the carb to cylinder gasket had dried out to the point that it was almost dust when I took it apart, someone had made that gasket and done a poor job and who knows what they used but it was not good gasket material. The other day my brother bought an old Honda TL125. When I started it, it smoked like a train. I started to take it apart and some SOB had used what we used to call cat glue made by Caterpillar to put it together at one point and time. Liked to not got it apart and even worse was getting the gasket surfaces clean and ready to put back together. You never know until you start disassembly.

Brian

 

[heimannm]

Good point Brian - if the automatic oil pump is not properly installed and well sealed the port through the oil tank will leak.

Brandon - listen/bubble check the area around the base of the automatic oil pump.

Mark

 

[brandonstc6]

I made some plates to block off the intake and exhaust when testing saws, rubber blanking gaskets are pretty handy here.

Gorilla tape will also work for vacuum testing but you need something more for the pressure test.

Mark

I have some rubber from an old car tire inner tube. I will try that next time I re-test.
Also I have the oil tank top off and I sprayed soapy water around the oil pump.


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[brandonstc6]

Good point Brian - if the automatic oil pump is not properly installed and well sealed the port through the oil tank will leak.

Brandon - listen/bubble check the area around the base of the automatic oil pump.

Mark

Thanks, I will re-visit that area.


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[2broke2ride]

$65 for a 550 seems to be a good deal but you don't know what has been done to it. That red knob on the side of the AF cover is definitely not stock.

View attachment 566530

Mark

I also noticed the red knob and was wondering what it might be, I know it's not stock lol, actually looks like a wire but to me.

What did these saws have for a carb? I was thinking it may have been a flatback with inop primer and this was some farmers work-around lol.

 

[heimannm]

The 550's did come with the primer flat back. Hard to say what that knob is for.

2broke - for you pig rich saw, the correct position of the metering needle is level with the body of the carburetor.



Older flat back carburetors had a sintered metal plug they called a capillary seal under the large welch plug, but most later ones had a plastic ball check valve. If the check valve is somehow damaged it would allow too much fuel to pass at low speeds. Fi the ball was missing altogether it might explain too rich at higher speeds as well as the ball does obstruct the flow somewhat.

If you want to pop that 1" welch plug out and check, I can send you a replacement welch plug.

How confident are you that the H and L jets are in fact the originals and of the correct length?

Mark

 

[2broke2ride]

The 550's did come with the primer flat back. Hard to say what that knob is for.

2broke - for you pig rich saw, the correct position of the metering needle is level with the body of the carburetor.

View attachment 566545

Older flat back carburetors had a sintered metal plug they called a capillary seal under the large welch plug, but most later ones had a plastic ball check valve. If the check valve is somehow damaged it would allow too much fuel to pass at low speeds. Fi the ball was missing altogether it might explain too rich at higher speeds as well as the ball does obstruct the flow somewhat.

If you want to pop that 1" welch plug out and check, I can send you a replacement welch plug.

How confident are you that the H and L jets are in fact the originals and of the correct length?

Mark

Mark, thank you for your help. I did remove the needles and compared them to another flatback that I have here that came out of my 380 and they where the same. The strange thing is that I took the carb apart because I felt it was running too lean before and I figured something was partially plugged in there. Didn't really find anything amiss in the carb and now it's running worse than before. Would a stiff metering diaphragm cause the lever to hang the needle open?
Btw I also put new crank seals in this saw as a first step to bringing it back to life.

 

[fossil]

That red knob is indeed a wire nut. Looking forward to see what it's doing so far back on the cover.

The guy could have at least used a yellow on.

 

[fossil]

I have some rubber from an old car tire inner tube. I will try that next time I re-test.
Also I have the oil tank top off and I sprayed soapy water around the oil pump.


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I've found the exhaust port hard to seal off unless you cut the rubber so it fits into the same machined slot as the gasket.

 

[2broke2ride]

So worked on the 440 for a couple of hours again tonight...... the metering lever was indeed set too high. Set it proper and put the car back together. I also swapped the mixture screws from my other flatback because they seemed to hold and adjustment better. I got it running and took it out to tune it in wood.
Got the high side tuned in good for a nice smooth cut and a little fourstroke unloaded. Then was messing with the idle speed and the lower mixture to try to get it to idle a little better and it just shut off like I hit kill switch. Now I seem to have lost spark. I took it back apart and cleaned and regapped the points twice now and still no joy. It will dimly light my spark tester but won't jump the gap on the plug with the plug held against the head.
So after a second time taking it apart and cleaning the points I got frustrated and came inside.

Does anyone think my cool just gave out? This is my third "big" Mac and haven't had an ignition problem that couldn't be fixed by dressing the points. Oh btw I also unhooked the kill switch and visually inspected the wire from the points to the coil.

 

[brandonstc6]

I've found the exhaust port hard to seal off unless you cut the rubber so it fits into the same machined slot as the gasket.

I didn't think about that, it very well could be my problem. I didn't have the gasket in the machined slot either when testing. I will try that.
Thanks for the help.


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[fossil]

A little goofy, but next time you are checking seals under vacuum I've found they whistle (sometimes) when you spray oil lie WD 40 on the rubber part of the seals if they are leaking. It can help to pinpoint the problem.

I would leave the gasket out and just use a piece of inner tube or two if the thickness requires it. That will eliminate the gasket as an issue when testing.

 

[svk]

So worked on the 440 for a couple of hours again tonight...... the metering lever was indeed set too high. Set it proper and put the car back together. I also swapped the mixture screws from my other flatback because they seemed to hold and adjustment better. I got it running and took it out to tune it in wood.
Got the high side tuned in good for a nice smooth cut and a little fourstroke unloaded. Then was messing with the idle speed and the lower mixture to try to get it to idle a little better and it just shut off like I hit kill switch. Now I seem to have lost spark. I took it back apart and cleaned and regapped the points twice now and still no joy. It will dimly light my spark tester but won't jump the gap on the plug with the plug held against the head.
So after a second time taking it apart and cleaning the points I got frustrated and came inside.

Does anyone think my cool just gave out? This is my third "big" Mac and haven't had an ignition problem that couldn't be fixed by dressing the points. Oh btw I also unhooked the kill switch and visually inspected the wire from the points to the coil.

A failing coil can cut out when it gets hot? Just a stab in the dark.

 

[fossil]

Anyone know anything about a PM 375? Mini Mac with a rear handle or?