McCulloch Chain Saws

[fossil]

The carb is a Walbro 37. The fuel pump cover states Walbro in large font. Hindsight, I’m going to revisit the carb rebuild. Looking at the IPL for the carb, I made a couple mistakes. For one, the fuel pump side has 2 diaphragms and I used only one. On the metering side, the gasket looks thick. I used the thinner of the 2 supplied gaskets. I’m gonna address these things before I touch the Welch plugs. I must have been thinking I knew more about carbs than the designer. Lol.

The thick and thin gaskets supplied are for the pump side. Stick with the thin gasket on the SDC-37.

The metering side is the one with the diaphragm that has the metal disc riveted into it.

 

[Joe Crow]

Put carb together according to the IPL and I still get spit. Set metering arm position according to Walbro site, it was a little high. Pulled flywheel and filed points, set to .020. Runs better, but still spitting fuel. I’m gonna replace the Welch plugs next and try that. I have a used SDC3 carb I could try as well. Muffler and port is clean.

I had the same problem with a Stihl spitting fuel out of a Walbro carb. This was after rebuilding the carb. I bought a carb pressure tester on Amazon and it showed leaking through the needle valve as well as the gasket. I had to double up the gasket on the needle value side to keep the diaphragm from pushing the needle valve open when tightening the cover. Worked great without the cover with one gasket. Pressure tester told the story.

 

[edju1958]

I'll be outta action for a while,had thumb surgery yesterday.Definitely not a picnic! Does this look familiar Mark?

 

[rwoods]

Prayers for a quick recovery, Ed.

Ron

 

[McCullochfiremen47]

Hope it heals up ED!
Intake side is Motosealed up now the wait .

 

[Jeffrey F.]

I'll be outta action for a while,had thumb surgery yesterday.Definitely not a picnic! Does this look familiar Mark?

best wishes and a speedy recovery

 

[Jeffrey F.]

quick question on Flat Back Primer. Is below assembly right or do I have the part with the hole wrong way. I figured out an way to get this out with out buggering it up. And does "O" ring go there? Really questioning why its there as it floats.



I drilled and tapped a 10/32 hole in end and pressed the whole thing out with a long 10/32 bolt.



Now just to get the one part in right direction

 

[bob kern]

I'll be outta action for a while,had thumb surgery yesterday.Definitely not a picnic! Does this look familiar Mark?

Heal up quick!!!

 

[piglosi]

The thick and thin gaskets supplied are for the pump side. Stick with the thin gasket on the SDC-37.

The metering side is the one with the diaphragm that has the metal disc riveted into it.

Thank you fossil,
Understood, and yes I stuck with the thinner of the gaskets on the pump side. Metering side is fine. Still spitting. Both Welch plugs are damaged. I don’t know if these damaged plugs are causing a rich condition or fuel spit out.

 

[piglosi]

I had the same problem with a Stihl spitting fuel out of a Walbro carb. This was after rebuilding the carb. I bought a carb pressure tester on Amazon and it showed leaking through the needle valve as well as the gasket. I had to double up the gasket on the needle value side to keep the diaphragm from pushing the needle valve open when tightening the cover. Worked great without the cover with one gasket. Pressure tester told the story.

Interesting, thank you Joe. I have another metering side gasket to try.

 

[edju1958]

Thanks everyone for your well wishes & prayers! Doc told me today that it'll take 3-4 months before I'll be able to do things without having an excess of pain.I was hoping to get out cutting this fall,but it's not looking very promising.

 

[bob kern]

Thanks everyone for your well wishes & prayers! Doc told me today that it'll take 3-4 months before I'll be able to do things without having an excess of pain.I was hoping to get out cutting this fall,but it's not looking very promising.

You gonna have wood for heat?

 

[Rocker59]

Thank you fossil,
Understood, and yes I stuck with the thinner of the gaskets on the pump side. Metering side is fine. Still spitting. Both Welch plugs are damaged. I don’t know if these damaged plugs are causing a rich condition or fuel spit out.

Could be a check valve issue also. Half of the plugs I've seen have a round indentation (about half the size of the plug) in them. This is from the punch used to expand them. I've also seen them set with a chisel/screwdriver. If you remove the welch plugs, remember to take the Lo and Hi needles out first. You can damage the Hi needle very easily if you don't.

 

[Woodslasher]

Interesting, thank you Joe. I have another metering side gasket to try.

Stupid question, but have you checked and made sure your metering lever is set to the right height?

 

[piglosi]

Could be a check valve issue also. Half of the plugs I've seen have a round indentation (about half the size of the plug) in them. This is from the punch used to expand them. I've also seen them set with a chisel/screwdriver. If you remove the welch plugs, remember to take the Lo and Hi needles out first. You can damage the Hi needle very easily if you don't.

Thank you fossil for the info. However, I was just back in that carb and changed the metering needle. I didn’t initially change it when kitting the carb because the hold down screw was aweful tight. Well I got it out and the tip of the needle had a large groove worn in. New needle in, readjusted lever height and I will try saw again.

 

[piglosi]

Thank you fossil for the info. However, I was just back in that carb and changed the metering needle. I didn’t initially change it when kitting the carb because the hold down screw was aweful tight. Well I got it out and the tip of the needle had a large groove worn in. New needle in, readjusted lever height and I will try saw again.

Sorry, Rocker 59, thank you for the info!
I’m trying everything before I screw with those plugs! I read many old postings on here about the sdc37. Seems to have a pretty good reputation

 

[piglosi]

Could be a check valve issue also. Half of the plugs I've seen have a round indentation (about half the size of the plug) in them. This is from the punch used to expand them. I've also seen them set with a chisel/screwdriver. If you remove the welch plugs, remember to take the Lo and Hi needles out first. You can damage the Hi needle very easily if you don't.

Fingers crossed I got this carb problem licked. Grateful for the opportunity to work on these great saws.

 

[knightmax]

Remember just the other day when I said about the 10-10S...."It MAY be the cleanest unrestored saw I have ever seen in person that was not still NIB NOS."?

Well here gentlemen we have a contender for the title in this PM700...

 

[bob kern]

Remember just the other day when I said about the 10-10S...."It MAY be the cleanest unrestored saw I have ever seen in person that was not still NIB NOS."?

Well here gentlemen we have a contender for the title in this PM700...

View attachment 1106243View attachment 1106244View attachment 1106245View attachment 1106246

No way that's been used!!!!!?????
Awesome saw.

 

[edju1958]

You gonna have wood for heat?

I've got plenty of wood for heat.I just wanted to go out cutting this fall.I only got about 12 cord in this spring,plus what I had left from last yr. - about 25 cord.I like to keep 2 yrs.ahead.