McCulloch Chain Saws

[jon lambert]

You probably have a exposed wire from the coil look for a spark when it's running

 

[heimannm]

Most of the Tillotson HL carburetors used on McCulloch saws had the same throttle bore and venturi size (.812/.687), the exception was the HL291 used on some 895 saws and the PM105 (1.00..875). The only other larger bore Tillotsons McCulloch used were the HL272 and HL288 on the 940 two man saws and some 170 welders, same throttle bore and venturi size as the 291.

You should try to find a carburetor from another top tank saw, preferably from a saw that did not have an air vane governor so the 291 would be ideal, except that they are very rare...

All of the MAC/Walbro carburetors used on saws had the same .812/.687 throttle bore and venturi size and the HL's used on most of the saws.

There are plenty of kits available for the MAC/Walbro carburetors these days, you might consider a rebuild of the original. The primers can be rebuilt as well, I posted some information here on AS (see the link in my signature) and Parker Jameson put together a YouTube video.

Parker's primer video



There is also a MacGyver using a purge bulb but I think that might move too much fuel and could result in flooding issues.



Mark

 

[fossil]

Most of the Tillotson HL carburetors used on McCulloch saws had the same throttle bore and venturi size (.812/.687), the exception was the HL291 used on some 895 saws and the PM105 (1.00..875). The only other larger bore Tillotsons McCulloch used were the HL272 and HL288 on the 940 two man saws and some 170 welders, same throttle bore and venturi size as the 291.

You should try to find a carburetor from another top tank saw, preferably from a saw that did not have an air vane governor so the 291 would be ideal, except that they are very rare...

All of the MAC/Walbro carburetors used on saws had the same .812/.687 throttle bore and venturi size and the HL's used on most of the saws.

There are plenty of kits available for the MAC/Walbro carburetors these days, you might consider a rebuild of the original. The primers can be rebuilt as well, I posted some information here on AS (see the link in my signature) and Parker Jameson put together a YouTube video.

Parker's primer video



There is also a MacGyver using a purge bulb but I think that might move too much fuel and could result in flooding issues.



Mark

I put one on an old 1969 77cc Pioneer .

All you need to figure the number of shots on the bulb.
Doesn't look great but it does the job well.

 

[Howsitgoineh]

Posting just for fun.. got my Mac 300 finally going like it should, put a 30" Windsor bar and chain on it. Can't wait to bury this thing

 

[heimannm]

This is the last Mini Mac I will work on (this week...)





Ed - when you assemble the tank to the saw, make sure the oiler fitting slips into the hole in the tank.







The only hiccups today were incorrect order of assembly on the fuel pump diaphragm & gasket (guess I should have stopped for lunch a bit sooner) and my attempt to use blue LocTite on the idle speed/throttle lock screw. I failed to take into account the fact that is a through hole in the carburetor directly over the throttle shaft...as a result I had to disassemble the saw one last time to free up the throttle.

Mark

 

[Howsitgoineh]

This is the last Mini Mac I will work on (this week...)

View attachment 1144871

View attachment 1144872

Ed - when you assemble the tank to the saw, make sure the oiler fitting slips into the hole in the tank.

View attachment 1144873

View attachment 1144874

View attachment 1144876

The only hiccups today were incorrect order of assembly on the fuel pump diaphragm & gasket (guess I should have stopped for lunch a bit sooner) and my attempt to use blue LocTite on the idle speed/throttle lock screw. I failed to take into account the fact that is a through hole in the carburetor directly over the throttle shaft...as a result I had to disassemble the saw one last time to free up the throttle.

Mark

Nice job Mark, looks almost brand new!
I have a few too handles, but I definitely gotta get myself some mini macs

 

[mattscof]

I know heimannm has a lot of McCulloch Chain Saws, as well as myself, I was wondering if anybody else has a few McCullochs in their collection of Chain Saws, and are they for work, or for display. Thanks for your input. Bruce.

I currently am in the process of doing a light rebuild and attempting to do a full restoration on a McCullough 550 that I bought off of Facebook marketplace for $25

 

[xl130]

Most of the Tillotson HL carburetors used on McCulloch saws had the same throttle bore and venturi size (.812/.687), the exception was the HL291 used on some 895 saws and the PM105 (1.00..875). The only other larger bore Tillotsons McCulloch used were the HL272 and HL288 on the 940 two man saws and some 170 welders, same throttle bore and venturi size as the 291.

You should try to find a carburetor from another top tank saw, preferably from a saw that did not have an air vane governor so the 291 would be ideal, except that they are very rare...

All of the MAC/Walbro carburetors used on saws had the same .812/.687 throttle bore and venturi size and the HL's used on most of the saws.

There are plenty of kits available for the MAC/Walbro carburetors these days, you might consider a rebuild of the original. The primers can be rebuilt as well, I posted some information here on AS (see the link in my signature) and Parker Jameson put together a YouTube video.

Parker's primer video



There is also a MacGyver using a purge bulb but I think that might move too much fuel and could result in flooding issues.



Mark

Thanks for the great advice and videos. That’s going to be a big help. The old Mcculloch carb is functional now but I was contemplating swapping it out. If rebuilding the system is easy enough and parts are still available then I will probably just keep the carb original for as long as possible. “ if it ain’t broke, don’t fix it”. I do have a HL63D that may do the trick but would likely require some tinkering to get the choke to operate properly.

How did you find all the specs for the HL carbs? Personal knowledge or is there a spec sheet to reference??

 

[heimannm]

Most of the information comes from the McCulloch Carburetor Guide publications. As many have discovered, McCulloch documentation was not always totally reliable...

Mark

 

[Howsitgoineh]

I currently am in the process of doing a light rebuild and attempting to do a full restoration on a McCullough 550 that I bought off of Facebook marketplace for $25

Looking good great deal especially if she doesn't take much to get going.
Love these old large frame McCullochs. Mine came with a stock 16" bar.. for an 89cc saw

 

[bob kern]

I have a 200 that's on the " I'll get to it eventually " list. I know it's impractical for daily cutting but sure would be good to hear it roar back to life!

 

[matt_lamb_160]

Hello Mac people! I’m looking for some advice on known HL carburetors that can easily replace the flat back for a 795. I tried searching this forum but could not really find what I was looking for. Would the smaller cc 250 or 1-72 Tillotson work or is the bore on the 795 flat back larger on the 100cc saws?

Any advice or suggestions are very much appreciated!

I personally prefer the Flatback over the Tillotson and following Mark's advice thry can be repaired as needed. I find they are less sensitive to ageing than the Tillotson, idle better and are perhaps more responsive.

If you want to put a Tillotson on it, many HL series are not too bad to adapt. A few people have put HL 324a carburetors on their McCullochs. I did a clone version when I was short on carbs to put on my 550, it worked (poorly on transition), but I don't recommend them.

 

[heimannm]

Mark

 

[Jethro 2t sniffer]

That's a really nice 10-10 Mark

Little update on the bars. I have two good tips out of the three. The machine shop guys want to make bearings for the 3rd just cos they like a challenge
But anyway a 20 for the sp70 and 24 on the 81. Guess I better hurry up n get on to those air leaks.

Not much time though berries berries berries

 

[edju1958]

That's a really nice 10-10 Mark

Little update on the bars. I have two good tips out of the three. The machine shop guys want to make bearings for the 3rd just cos they like a challenge View attachment 1145257View attachment 1145258View attachment 1145259
But anyway a 20 for the sp70 and 24 on the 81. Guess I better hurry up n get on to those air leaks.

Not much time though berries berries berriesView attachment 1145260View attachment 1145261View attachment 1145262

I had strawberries for many yrs.,then they just kinda died out.I also had wild blackberies that seeded themselves & they died out too.I still have my raspberries though that I've had for 35 yrs.now.I also planted 2 mulberry trees over 30 yrs.ago,the birds love 'em.The mulberry wood is some of the hardest wood I've ever come across,harder than oak IMO.

 

[Jethro 2t sniffer]

I had strawberries for many yrs.,then they just kinda died out.I also had wild blackberies that seeded themselves & they died out too.I still have my raspberries though that I've had for 35 yrs.now.I also planted 2 mulberry trees over 30 yrs.ago,the birds love 'em.The mulberry wood is some of the hardest wood I've ever come across,harder than oak IMO.

Dang birds always ruining the party.

 

[edju1958]

Dang birds always ruining the party.

I planted the mulberry trees to attract the birds.Now it seems the birds can't tell the difference between the mulberries & sour cherries,they both get ripe at the same time - right around Independence Day. (that's July 4th for you non- U.S.residents,Lol)

 

[heimannm]

The 6-10 (like a few other -10 saws) does not have a full "channel" for the fuel tank gasket so I had to use a cork gasket and Pliobond to achieve a tight seal.



I thought I'd let the Pliobond set up overnight before adding fuel, but it did fire off on a prime directly down the carburetor.

Mark

 

[heimannm]

Backwards on the 6-10 today, fuel tank still leaked, oil tank was leaking at the seam, and the carburetor shaft was so sloppy the tune kept changing.

I gave the fuel tank a Red Kote treatment, flattened the front of the oil tank to eliminate the ridge due to long term wear, and I found another carburetor I'll try once the Red Kote fully cures.

Mark

 

[matt_lamb_160]

I really like those 6-10s. I have a soft-spot for the RH start saws and the 70cc with no anti-vibe makes for a strong performer in such a light, neat and compact unit.