McCulloch Chain Saws

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edju1958

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I think I might've addressed this once before here.I have 2 PM55 cylinders (short blocks actually),one has a wallowed out plug hole that I doubt a Time Sert would even work in,the other has a wallowed out boss for 2 of the muffler bolts.One of the bosses can be helicoiled,the other one is beyond a helicoil.Has anyone tried using "blue demon" aluminum/zinc brazing rods for such a repair.The rods need a hotter gas than propane,usually map gas can be used.Obviously the engine would have to have the cylinder taken off for such a repair.Once the boss is filled with the new alloy it could be drilled out & either re-tapped,or a helicoil put in.
 

matt_lamb_160

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Just for anyone who cannot see what Syncop8r is missing (you can probably all see it, but...). It is a screw in the main body which without you have a big hole in the carb body and no idle adjustment. Many SDCs don't have this and adjust off of the throttle arm/lever only (and trigger as mentioned)


 
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Use your thumb to pull up on the protrusion at the front with the throttle held open and it will latch the throttle open. The fast idle speed can be adjusted with the screw in the bottom of the throttle trigger or in some cases (like the 10-10S) in the bottom of the throttle release (Item 11).


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Mark
 
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I think I might've addressed this once before here.I have 2 PM55 cylinders (short blocks actually),one has a wallowed out plug hole that I doubt a Time Sert would even work in,the other has a wallowed out boss for 2 of the muffler bolts.One of the bosses can be helicoiled,the other one is beyond a helicoil.Has anyone tried using "blue demon" aluminum/zinc brazing rods for such a repair.The rods need a hotter gas than propane,usually map gas can be used.Obviously the engine would have to have the cylinder taken off for such a repair.Once the boss is filled with the new alloy it could be drilled out & either re-tapped,or a helicoil put in.
Well ed id say whats it gonna hurt. Especially if they arent being used now due the damages. Give it a shot.
 

Syncop8r

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Just for anyone who cannot see what Syncop8r is missing (you can probably all see it, but...). It is a screw in the main body which without you have a big hole in the carb body and no idle adjustment. Many SDCs don't have this and adjust off of the throttle arm/lever only (and trigger as mentioned)



Yep no idle screw and spring, just a big hole.

It might be easier to find a whole new carb (although this carb otherwise functions well) - can I steal one off a 610? 🤔

I note the SDC 44 from my PM60 didsn't come with that idle screw.
 
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I have posted this information before, sorry about the formatting. Idle adjust is noted as internal (screw in the carburetor) or external (screw in the air box).

McCulloch Carburetor Usage – SDC & Zama C2 Carburetors

Carburetor Venturi Throttle Idle Hi


SDC 2 .625 .750 Ext Adj

SDC3 .625 .750 Int Adj

SDC4 .625 .750 Int Adj 10-10

SDC7 .625 .750 Int Adj Mac 15 (no FP)

SDC16 .625 .750 Ext Adj

SDC18 .750 .812 Ext Adj

SDC19 . .750 .812 Int Adj

SDC20 .750 .812 Int Adj

SDC22 .750 .812 Ext Adj

SDC37 .750 .812 Int Adj

SDC38 . .750 .812 Ext Adj

SDC38A .750 .812 Ext Adj

SDC43 .750 .812 Int Fixed

SDC44 . .750 .812 Ext Adj

SDC49 .750 .812 Int Fixed

SDC50 . .750 .812 Int Fixed

SDC51 .750 .812 Ext Fixed

SDC65 .750 .812 Int Adj

Mark



Zama C2 .750 .812 Ext Adj PM850, 800, 805
 

edju1958

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Yep no idle screw and spring, just a big hole.

It might be easier to find a whole new carb (although this carb otherwise functions well) - can I steal one off a 610? 🤔

I note the SDC 44 from my PM60 didsn't come with that idle screw.
The carbs used on a PM610 are a totally different animal.The adjuster needles are probably too long,the linkages won't line up (especially the unique choke assembly),& I doubt the carb will even mount up properly.
You may indeed be better off trying to find another entire carb,if only for parts.
 

knightmax

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I'll be. It has the in-handle trigger safety that is depressed with your palm when you grip the rear handle, but I didn't know it was also a trigger lock/fast idle switch, if that's what you mean. I had that all apart for painting and didn't catch that. :rolleyes: I'll look at it again tomorrow.
View attachment 1036477
depress the trigger pull the little black tab back thats below the kill switch back..release throttle it should lock back. Vroom Vroom!
 

knightmax

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So as most here know, for months now I have been focused on getting the building ready for Bob Johnsons parts. well yesterday I decided to see if I remembered how to fix saws. My neighbor and my Dad's high school class mate gave me a 10-10A a while back. he said the small engine shop he took it to years ago said the compression was to low for the saw to run correct. So yesterday I checked it out...compression good, spark good. I pulled carb and threw it in the ultra sonic. I put in a kit today and Vroom! runs fine. I cant believe some of the small engines shops and the apparent lack of knowledge. Sad really. I am going to offer the saw back to the original owner as he is a friend and neighbor and stated he loved the saw.

On a side note I talked to Joan (Bob Johnsons live in partner) she said they disconnected the phone to Bobs shop last week. Its officially over. I was hoping he would get back in the shop and tinker with the parts he still has (which are a lot). Joan said Bob is developing memory loss issues. It's sad, ending of an era. So much knowledge leaving us.

Max
 

Jethro 2t sniffer

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SDC44 with no idle screw?
View attachment 1036801

Yeah some of them use a idle screw in the airbox that pushes on that flat area on the throttle outside of the carb. Others like the sdc 65 are like your carb. The thing is the 44 doesn't have a big hole in the side of the carb which may or may not affect it at all.

Try Mark's trick n bend the rod
 

Syncop8r

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Yeah some of them use a idle screw in the airbox that pushes on that flat area on the throttle outside of the carb. Others like the sdc 65 are like your carb. The thing is the 44 doesn't have a big hole in the side of the carb which may or may not affect it at all.

Try Mark's trick n bend the rod
Cheers.
It wasn't a reference to my carb that is missing the screw though. 😬
 
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