MCCULLOCH The official McCulloch thread

[heimannm]

Some while back I stopped by fellow member Ike Holt in IN and got a load of parts, several saws, and his BP-1 to get going again. The BP-1 was finished and returned a few weeks ago and I have been working on the CP70L for a couple of weeks now. It was very clean and appeared to be very low hours, but it would hardly crank over and felt stiff and crusty. Following the good advice and example of Randy Evans a complete tear down was in order.

I did not take a lot of photos but when I pulled to cover off the oil tank, there was water inside... When I split the crank case it was badly corroded on the bottom half, evidently the crankcase bottom/oil tank is made from magnesium and the cylinder/block is made from aluminum. I cleaned it up as best I could but had to resort to sandblasting to get all of the corrosion out.









I used some Lock Tite two part epoxy to coat the inside of the crankcase bottom.



Mark

 

[Al Smith]

Just for general info in case nobody knew that screw adjusts the travel of the piston >more travel,more oil .Those oilers BTW if working properly will literally blow oil off a 32" bar .

 

[heimannm]

For anyone working on 10 Series McCulloch saws, here is some information that may be useful.

Flywheel side



PTO side



Steve gave the National/Timken numbers for the seals a page or two back, the double lip seal for the PTO side SKF number is 62119.

Mark

 

[heimannm]

I tried Ted's trick today on the stale gas/varnish accumulation in the tank, hot water and purple power followed by lots of hot water with Dawn dishwashing detergent. I put 25 8-32 nuts in the tank and shook a aggressively as possible, changing the water and detergent several times. Low and behold, in 30 minutes or so the inside of the tank was amazingly clean.

Finished putting the saw together and added one of the cool Sabre 20" roller nose bars from Fossil to finish it off. This one has never had a spike so for now I left the clutch cover as I found it.











I have the 2-10PS recently acquired via Tylerjeep from AS, and the Super 2-10 Automatic from Eccentric to get cleaned up and going, then hopefully the 1-81 and then back to the 101 powered saws.

Mark

 

[WOODS]

When you remove the automatic oil pump, you will see the pulse path straight into the crankcase.

View attachment 14147

With the automatic oil pump off, check to make sure it is pumping by operating the piston manually. Oil will be drawn into the green circled port and discharged out of the red circled port.

View attachment 14148

If the manual oiler works but the automatic does not, chances are the piston is stuck. I found a few that had broken out the center of the phenolic disc.

View attachment 14150

Did you try adjusting the flow by backing out the screw in the top of the automatic pump?

Mark

This pump I overhauled some time back when I rebuilt the saw. The problem then was the little o-ring that holds the piston on. I thought that was the only problem so I didn't tinker with the settings. As part oof the rebuilt I drilled it so I could screw down the pump which means I'll have to take the gas tank off to remove the pump. In hindsight I should have operated it manually and checked the pulse path as this saw never smoked like almost all of mine did before I started screwing the pumps down.

Just for general info in case nobody knew that screw adjusts the travel of the piston >more travel,more oil .Those oilers BTW if working properly will literally blow oil off a 32" bar .

My dad always ran used motor oil. His MACs would throw that stuff like mad - including the little PM6As.

Ron

 

[heimannm]

I solved my PM6 lack of oil by simply adjusting the screw. Amazing how much difference it makes. (old photo) The adjuster screw in in that angled protuberance at the front of the saw, the screw is supposed to be flush with the neck for a starting place.

Ron, try backing out the screw in the top of the pump to see if that gives you more automatic oiling.



Mark

 

[ft. churchill]

Hey folks, I picked up a clean Mac 550 to work on, I was told it needs oil seal on the crank. Does anybody know what the part number is for these or a crossover number for a national or Chicago rawhide seal is? May be evn have a set for this saw? Thanks.

 

[heimannm]

They are both standard sizes and I know I have them recorded somewhere but not with me right now.

Often it is the PTO side that has failed from grass, straw, string, etc. getting wrapped up on the crank shaft and wearing into the seal. The PTO side can be removed pretty easily once the clutch is off if you are willing to drill a small hole and use a slide hammer type puller.

I will try to remember and look at some notes tonight for the seal sizes/details.

While I enjoy running a 550 or Super 550 ever now and then, the SP105 really puts them to shame.

Mark

 

[Mastermind]

This thread is chock full of great info. I'm glad you guys are here.

 

[ft. churchill]

Thank you Mark, I'll look for your post. I was hoping to find the sizes before I tore it apart.

 

[Al Smith]

Flywheel side McCulloch 50663 /Cr 6763 .Clutch side McCulloch 104432 /Cr 6816 --I have the Cr master interchange book among other things

 

[ft. churchill]

Thank you Al, you made my day.

It is wonderful to have a site like this where we can get info.

 

[WOODS]

This thread is chock full of great info. I'm glad you guys are here.

How's your PM850 project coming?

I need some secret tips so I can get my PM800s up to the 850 performance I keep hearing about from the wise MAC heads. I don't like being the quieter younger step-child.

Ron

 

[heimannm]

I can't help with the 800/850 problem except to say Mimosi has a NOS 850 cylinder, crankcase, and piston w/rings up right now for $20o right now on eBay.

My information agrees with Al on the standard series large frame saws.

I don't have the manufacturers numbers for the super series (top tank) but my notes say 35x17x7 PTO side and 30x17x7 on the flywheel side. Certain models had a second seal as well only available as 57897 and 30x17x6 mm thick. I have seen the thin seals installed both ways, lips in and lips out, inside seal is lips in.

Mark

 

[Mastermind]

How's your PM850 project coming?

I need some secret tips so I can get my PM800s up to the 850 performance I keep hearing about from the wise MAC heads. I don't like being the quieter younger step-child.

Ron

It's running nicely. I don't have any performance tips either. I'm too pressed for time to play with them much.

 

[WOODS]

I can't help with the 800/850 problem except to say Mimosi has a NOS 850 cylinder, crankcase, and piston w/rings up right now for $20o right now on eBay.

And to think I sold my NOS 850 c&c for $20.00 plus postage just a few years ago to an AS member who had a project in mind. I never did hear what he did with it.

It's running nicely. I don't have any performance tips either. I'm too pressed for time to play with them much.

You didn't shave a 1/16th" off the piston on the intake side? I had heard a rumor that that tip was from you so I did it on a coated piston that I used on an "A" cylinder. Unfortunately, mine seized before I could test it. Someone who will remain nameless didn't get all the transfer off the cylinder - blamed it on lack of shop lighting. I hope to resurrect it as soon as I get my, I mean his, lighting issues resolved. I don't think the coating was the reason but the extra thickness didn't help.

Ron

 

[Al Smith]

A tip on that 800,get rid of that screen muffler .Those things aren't worth a pinch of coon chit .You are dumping that exhaust like right into a brick wall .Way to much resistance for performance .
The best ones are like on the SP 81 or the early style 850 .If it's the reed cover ditch that thing,they never did work right .They could have several baffle plates within ,maybe a screen ,remove same and just use the plane cover .They'll be a tad loud but they'll run a lot better .Wear muffs,solved that problem of loud .

As a side note I have a 6-10,right hand start 70 cc with a gutted muffler .It will make dogs howl.It will also crank on at over 15 thou .So much for the theory that all McCullochs are slow.

 

[Mastermind]

I did cut a piston on one for Joey. He said it helped.

I didn't really see any sure gains aside from that though.

 

[WOODS]

Thanks for the replies, guys.

Of possible interest to Randy, MAC claimed the 800 had more ponies than the previous 850 (last one of the DSP in the head design and last one without the Q-port exhaust). The new design included with the Q-port a revised intake port. I will try to find and post pictures tonight. I don't know enough two cycle principles and theories to hazard a guess as to whether the two port changes are related much less their effect on performance. The only other apparent performance change was the muffler.

Ron

 

[Ikeholt]

I wonder if any current saws use a Q-port? Maybe the idea died. Seems to take some of the of the zip out of them.

Mark, on that water in the CP 70. Makes perfect sense now, the guy I got it from mumbled something about it being a boat anchor...

I finally have my SP125 restored and running good. I couldn't find a coil for it, so I made one out of a Husky 55 coil. It was a fast and cheap mod. Husky 55 coils are solid state and only cost 10 bucks. I just swapped the laminates and bolted it on. Not sure this pic will load.