McCulloch Chain Saws

[Im_a_Broom]

In order to determine the number of drive links in your chain you need to confirm the bar length and the pitch of the chain. Many of the McCulloch 10 Series saws used a somewhat unique .354" pitch chain which requires 61 DL on a 16" bar where 3/8 chain requires 60 DL. You also need to confirm the gauge of the drive links, as they used both 0.050 and 0.058" thick drive links. You also need to confirm the sprocket on the clutch matches the pitch of the chain as it was a common mistake to try and use a 3/8 sprocket with .354" chain and vise versa.

Thank you! I did get the chainsaw running, so now the last thing on my to-do list is to replace the chain. I counted the links in the chain yesterday and I counted 62. I counted twice to be sure I was correct. Short of taking the chainsaw to a repair shop or a dealer, is there a way for me to accurately measure the other things?

 

[Maintenance supervisor]

Great little tool fits in yoir wallet.

 

[Manic84]

Time for a bit of an odd question.
Heimannm, when you were looking for some teflon material a while back, did you ever find a good supplier or was it a bust?

 

[clint53]

View attachment 877254
Great little tool fits in yoir wallet.

Santa brought me one.

 

[heimannm]

I did find a source for the fuel pump material. Somewhat expensive but it is the correct material.

Carburetor Fuel Pump Diaphragm material (rt21trading.com)

I also found a source for nitrile covered nylon 0.006" thick for metering diaphragms or fuel pump diaphragms. I have several square feet of the nitrile.

Mark

 

[Maintenance supervisor]

Mark how much slop should there be in the big end of an 82cc mac ? There's a pretty audible thunk/thunk at tdc. Do the needles get changed oftentimes?

 

[heimannm]

I have not had one with excessive clearance on the big end. I know the wrist pin bearings sometimes fail and turn the needles loose...that's bad.

Mark

 

[Maintenance supervisor]

I have not had one with excessive clearance on the big end. I know the wrist pin bearings sometimes fail and turn the needles loose...that's bad.

Mark

I pressed old bearings into an aftermarket piston, from a used piston .
I haven't glued anything yet, just fitting everything together.

 

[Maintenance supervisor]

I don't have any play in the diameter of the crank just sea/saw from end to end .
Opinions welcome, but experience favorable.

 

[heimannm]

Having some axial movement is normal, even the rocking motion is not unusual, just make sure there is no radial play. The kart guys used to leave one or two needles out to give it a little extra clearance.

Mark

 

[vinnywv]

I don't have any play in the diameter of the crank just sea/saw from end to end .
Opinions welcome, but experience favorable.

Ive not had one apart yet that didnt do the same to some degree.

 

[vinnywv]

I do have a question also. So i finally got to my 40.00 7-10a yesterday. Got it all apart for cleaning. Its got good spark, good compression, id say itll be a runner before too long...my question comes from the clutch. The spider has threaded holes for the right hand start, which is not unusual. However it is a keyed clutch as is the crankshaft keyed and it had the key in it. So my question would be about age. Is this possibly an early 7-10? Most all of them are left hand start. I just found it interesting. It does have open transfers and a thick ring piston. The cylinder is not perfect but in good enough shape im not concerned. Any opinions are welcome. Thanks. Vinny

 

[heimannm]

The 1974 7-10 IPL shows the old style clutch cover and a keyed clutch. The 1976 7-10 IPL shows a later chain brake clutch cover and a non keyed clutch. The crankshaft with the keyway will have RH threads, the crankshaft without a keyway will have LH threads, Some of the guys will tell you the key is not needed provided you clean the shaft and lap the clutch a bit for a more perfect fit and torque the RH nut to spec's. I would be more comfortable with the key but I do understand the concern that if the nut comes loose the key will likely damage the keyway and possibly ruin the crankshaft. Keep the clutch torqued correctly to avoid any problems.

Mark

 

[vizette]

I need to do some welding repairs on the skids as well.

https://www.amazon.com/gp/product/B002MRM6KQ/

 

[Manic84]

I did find a source for the fuel pump material. Somewhat expensive but it is the correct material.

Carburetor Fuel Pump Diaphragm material (rt21trading.com)

I also found a source for nitrile covered nylon 0.006" thick for metering diaphragms or fuel pump diaphragms. I have several square feet of the nitrile.

Mark

Thank you Mark, you have helped me a great deal.

 

[vinnywv]

Thankyou mark. Appreciate that info. So its likely older than me by a bit...lol

 

[rarefish383]

Pulled the crank case in half on the 7-10. Came right apart, no gaskets, just thin layer of sealer. The bearings and crank are still tight in the block half. Should I gently tap on the crank to separate it. Is there something I'm missing. There is no play in the bearings. The engine was not painted. So, as Ira said, it may have been a replacement engine with low hours. I figured while it's this far apart I might as well replace all bearings and seals. Oh, I didn't pull the clutch off yet, unless the bearings are made of rubber, I guess I better go do that. Might as well slide the cylinder back on for extra support.

 

[Goinwheelin]

Pulled the crank case in half on the 7-10. Came right apart, no gaskets, just thin layer of sealer. The bearings and crank are still tight in the block half. Should I gently tap on the crank to separate it. Is there something I'm missing. There is no play in the bearings. The engine was not painted. So, as Ira said, it may have been a replacement engine with low hours. I figured while it's this far apart I might as well replace all bearings and seals. Oh, I didn't pull the clutch off yet, unless the bearings are made of rubber, I guess I better go do that. Might as well slide the cylinder back on for extra support.

Yeah I usually pull the clutch and flywheel before splitting the case. Gives you more to hang on to because sometimes they can be stubborn.

Rubber mallet to separate the crank and bearings from the case.

The guys here like Dirko for case sealant, but I’ve used Moto Seal and 100% silicone with equal success.

once you’ve done 1 Mac you’ll want to do another. WAY easier than the German and Swede saws when it comes to getting at the crank and bearings. At least in my experience.

 

[heimannm]

The PTO side bearings and seals for the 10 Series are standard supply, bearing is BH108 and the seal is SKF6119. The flywheel side varies, some bearings have a wide outer race and the seal presses into the bearing, others have a narrower bearing and the seal matched the O.D. of the bearing. The same narrower bearing and seal were used on the 600 Series saws and are usually available, the bearing has a groove for a snap ring that hold everything in the proper location in the engine.

Mark

 

[Maintenance supervisor]

As promised a short video of the pro mac 700 with 22" roller nose and skip tooth square chisel.
Upon cleaning the 700 up I discovered that I only had a 7 pin sprocket on it, I'll have to bump it up to an 8.