MCCULLOCH The official McCulloch thread

[Steve]

Silly question for you. Having never owned a saw this old what ratio mix should I put in it? I know we used to run the old dirt bikes pretty rich. Just don't want to do anything stupid and junk this old beast

Some of the real early mac saws did jot have wrist pin bearings. You need to run a rich mixture in those. Also the early macs that used crankcase scavenging for the chain oiler have to run real rich like 12:1 30wt non detergent engine oil if i remember correctly.

But your 55 is neither of those so 40:1 modern oil is just fine.

 

[Gizzard]

The 1-40 I have has the bushing instead of wrist pin bearing and used the scavenging system to send oil to bar pad as Steve mentioned. I got the accessory front oil tank added so it had manual oiler then and plugged the crankcase scavenging to bar pad and have been running 40:1 mix in engine. Run 7 pin .404 65dl on mac hardnose bar that measures out to about 18.5-19 inches. I like to use the saw, but don't use it hard so think all is good...at least it has been to date.

 

[Gizzard]

Note... enjoy running the 1-40, but having the manual oiler button on front of saw makes me think ahead when cutting as to when I'm going to reach around to front and depress it. Usually just oil bar/chain after a cut or stop in middle of cut. Don't like reaching up front there with chain chomping away.

 

[heimannm]

41 - here is a muffler modification you may want to try.



Mark

 

[heimannm]

You fellows have been slacking a bit...

I have a McCulloch trimmer that is giving me fits, any advice would be appreciated. New piston and cylinder, compression is around 125 PSI, crankcase holds pressure and vacuum. Spark seems to be O.K. I have been through the carburetor several times and it always passes the pressure test. I have checked and adjusted the metering lever to make sure it is just flush with the floor of the carburetor.

Unit will start easily, often without choking it at all. Runs fine for a minute or two then starts bogging down, threated to die if I open the throttle, and then dies and won't restart. You can hear what sounds like fuel boiling in the cylinder after it dies. Frequently when it is just setting there hot or cold it drips fuel out of the carburetor. How can that be if the metering needle is seating properly as evidenced by the pressure test? Has anyone had a bad experience with the check valves in the primer/purge bulb section of the carburetor?

Mark

 

[Steve]

You fellows have been slacking a bit...

I have a McCulloch trimmer that is giving me fits, any advice would be appreciated. New piston and cylinder, compression is around 125 PSI, crankcase holds pressure and vacuum. Spark seems to be O.K. I have been through the carburetor several times and it always passes the pressure test. I have checked and adjusted the metering lever to make sure it is just flush with the floor of the carburetor.

Unit will start easily, often without choking it at all. Runs fine for a minute or two then starts bogging down, threated to die if I open the throttle, and then dies and won't restart. You can hear what sounds like fuel boiling in the cylinder after it dies. Frequently when it is just setting there hot or cold it drips fuel out of the carburetor. How can that be if the metering needle is seating properly as evidenced by the pressure test? Has anyone had a bad experience with the check valves in the primer/purge bulb section of the carburetor?

Mark

I have had a few carbs that passed every test but still are just junk.

 

[heimannm]

Thanks Steve - I brought over a couple of carburetors from blowers with the same engine. I will try swapping them around tomorrow.

Mark

 

[Gizzard]

@heimann , I just had a carb pass tests but getting gas out air filter and fill crankcase. The main issue ended up being tank vent in gas cap was stuck solid and when that fixed stopped crankcase from filling up. The Zama carb still had issues though and complete rebuild kit w/ metering spring and cleaning and it would still act strange. This was a Husqvarna blower though. I have had duckbills go bad in primers too, but engine just not start then.

I can't remember model of McCulloch trimmer, but they were straight shaft, bike handle and no plastic to speak of around powerhead probably made '78-82 or abouts. They were nice cutting machines, but dealership had several new units for sale with new OEM ignition modules that were bad. Most would not even start if this was problem though.

Another thought is with Tanaka TBC-2501 trimmer I have that on hot days it makes that boiling gas sound in cylinder after shut down and refuel and try to start it. It has the rotary style carb and when push primer ...just here the boiling sound. Sometimes primer not get it going and would let it sit awhile or pour gas in cylinder to get restarted. I always thought about modifying plastic on that Tanaka to get better cooling....just thought about is all though. It still runs well and pulls near 150psi, but splines have wore off steel driveshaft and some other put it into retirement this week. Got 20 yrs hard hillside mowing out of that unit.

 

[Gizzard]

Definitely need to track down a muffler.View attachment 242307

If you had a 3.0-3.5 Tecumseh motor laying around you might check the round muffler on them and if could make it work (they would have round hole inlet in back of muffler though). I get to thinking on it one day will check this myself as have wondered about that. I think the hole spacing on the Mac may be a little wider though. I had sold last round Mac muffler I had, but you could watch for one of the stacks instead of round muffler that 80cc macs used. I have a 1-46 that had the round muffler, but sold it and put the stack in its place on the 1-46.

 

[Steve]

@heimann , I just had a carb pass tests but getting gas out air filter and fill crankcase. The main issue ended up being tank vent in gas cap was stuck solid and when that fixed stopped crankcase from filling up. The Zama carb still had issues though and complete rebuild kit w/ metering spring and cleaning and it would still act strange. This was a Husqvarna blower though. I have had duckbills go bad in primers too, but engine just not start then.

I can't remember model of McCulloch trimmer, but they were straight shaft, bike handle and no plastic to speak of around powerhead probably made '78-82 or abouts. They were nice cutting machines, but dealership had several new units for sale with new OEM ignition modules that were bad. Most would not even start if this was problem though.

Another thought is with Tanaka TBC-2501 trimmer I have that on hot days it makes that boiling gas sound in cylinder after shut down and refuel and try to start it. It has the rotary style carb and when push primer ...just here the boiling sound. Sometimes primer not get it going and would let it sit awhile or pour gas in cylinder to get restarted. I always thought about modifying plastic on that Tanaka to get better cooling....just thought about is all though. It still runs well and pulls near 150psi, but splines have wore off steel driveshaft and some other put it into retirement this week. Got 20 yrs hard hillside mowing out of that unit.

I always forget about the tank vent system Kevin.

 

[Gizzard]

I always forget about the tank vent system Kevin.

I missed one a week back and you reminded me of that on that rear tine tiller, "the butt kickr machine".

 

[Al Smith]

If you really wanted a McCulloch round muffler they pop up on flea bay all the time as do the little stub spark arresters .The prices are all over the place,typical E-Bay .That said I don't think they would be difficult to copy if a person had some basic sheet metal and welding skills .Use something like a short piece of 2"thin wall conduit for the barrel and a hole saw in a drill press to cut out the back and cover and gas weld it together .the thicker tubing material would last forever .You could do it in around 2 hours I'd think .

 

[Steve]

If you really wanted a McCulloch round muffler they pop up on flea bay all the time as do the little stub spark arresters .The prices are all over the place,typical E-Bay .That said I don't think they would be difficult to copy if a person had some basic sheet metal and welding skills .Use something like a short piece of 2"thin wall conduit for the barrel and a hole saw in a drill press to cut out the back and cover and gas weld it together .the thicker tubing material would last forever .You could do it in around 2 hours I'd think .

I charge 50 an hour in my home shop. Much cheaper to buy a decent used one. Plus cost of supplies. Nothing free.

Totally do-able like you said Al. Just dont think it would be worthwhile.

 

[Al Smith]

True but how many orders have you had for a duplicated McCulloch round muffler ?

 

[Steve]

True but how many orders have you had for a duplicated McCulloch round muffler ?

Not enough yet!

 

[Al Smith]

It's unlikely you ever will .

 

[Bigmac]

I wish someone would repop the directiononal round muffler! The gem box muffler is $50 new and won’t rot, but is overkill for most builds, but the outlet could be reduced too, and spark screen added

 

[Al Smith]

If I wasn't in the swamp ,azz deep in alligators I'd build one .The rusty old muffler I have on a 650 Gear drive is just about like having nothing .It's just a rusty old shell ,saw runs okay but blows black smoke before it clears it's throat and hits that power under load .In other words it's a main liner,open exhaust .Loud enough to make dogs howl .No wonder I have a ringa ding in my right ear .That or open exhausts on the old Cat D4's --or 50 years of industrial noise .

 

[Bigmac]

There are swamps in Ohio?

 

[Al Smith]

Of course there are .Actually I live about 3 miles south of an area once called the great black swamp which of course has been drained .Goes clear to lake Erie .Some of the most productive farm land in the USA .Flat as Kansas .https://en.wikipedia.org/wiki/Great_Black_Swamp ----The area on the other side of the county bordered on the great Scioto marsh where I grew up .Once the onion growing capitol of the world that until bad tillage practices caused about 6 feet of top soil eroded by the wind .There's about 12" of it left now .All that said there are no alligators .