McCulloch Chain Saws

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Why oh why will this saw not just start and run like all of my other saws??? Grrrrrrrr. I'm getting really good at pulling the carb out of it. Took out the carb and very carefully and deliberately tore it down. I currently have the hard parts soaking in acetone and am anxiously awaiting the Welch plug from Mark. Don't want to attempt removal without the new one on hand. I hope this is the last time. I really don't know where else to go from here. I'm usually really good with carbs but this thing is whooping me.

Is there a way to convert these old saws over to a modern style "cube" carb? And if so, which carb is best?
 
There is an adapter that will mount and SDC or similar carburetor, they were used on the Super 797 and a welder (I think). Part number is 83722. That is not a normal course to take...

Welch plugs will go out tomorrow.

Mark
 

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  • Mc Super 797 carburetor & adapter.pdf
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2broke2ride said:
I am getting really frustrated with this saw[emoji35]. This is the above mentioned 440. If you've been following along it was acting weird. Not responding to throttle idling strange, unable to rev. But if I played with it I could get it to rev out and it would run and cut well. So I pressure tested the crankcase and found a leak at the reed plate. Though I had it. So I just got it back together. Made all new gaskets for it, re pressure tested and all good. It still acting the same!!!!! It will idle forever although rough and doesn't sound right. But when you hit the throttle there is no change!!!! No bog, no rev, there maybe is a slight change in pitch at the carb throats but that is it. And to make matters worse, I can't even feather it to rev anymore. I got it to rev out once and when it did it sounded great, had a nice burble unloaded and cleaned up and pulled good in the wood. I don't know I'm stumped. Crank seals are new, been through the carb three times although still waiting on a kit from sugar creek. Resealed the reed plate.
It almost acts like the reeds are acting as sort of a throttle plate and not opening of that makes any sense. Sorry for the novel. Hoping someone can help.
Click to expand...
Out of curiosity have you checked the electrical portion out? I've seen saws act really whacky with a bad ground and or a condenser. I'd take the coil off and clean it good especially where the flywheel passes around the air gap space, check the wires, clean all areas where wires attach to get a good connection, check points, clean, set and also the air gap and see what that does if anything . Points at .018 I think and air gap .010.

If you've rebuilt the carb three times or so and also give it fuel squirting with the primer and no change maybe it isn't fuel at all. Sometimes it's good to just start from the beginning and Check it all out and make sure you have good connections.



Sent from my SM-T330NU using Tapatalk
 
Nickolas said:
Out of curiosity have you checked the electrical portion out? I've seen saws act really whacky with a bad ground and or a condenser. I'd take the coil off and clean it good especially where the flywheel passes around the air gap space, check the wires, clean all areas where wires attach to get a good connection, check points, clean, set and also the air gap and see what that does if anything . Points at .018 I think and air gap .010.

If you've rebuilt the carb three times or so and also give it fuel squirting with the primer and no change maybe it isn't fuel at all. Sometimes it's good to just start from the beginning and Check it all out and make sure you have good connections.



Sent from my SM-T330NU using Tapatalk
Click to expand...

I agree, and I've been through the ignition at least as many times as the carb. I've never experienced a bad condenser so I don't know how that would act. I could start swapping ignition parts with my 380 if this carb turns out to be a no go.
 
heimannm said:
There is an adapter that will mount and SDC or similar carburetor, they were used on the Super 797 and a welder (I think). Part number is 83722. That is not a normal course to take...

Welch plugs will go out tomorrow.

Mark
Click to expand...

Thanks mark.

Wasn't really intending to do that, was just curious if it could be done easily enough.
 
It does not sound electrical to me. It idles too smooth for that, but I could be wrong. It sounds like a air issue. You say that you open the throttle and also hit the primer and know that it is squirting fuel into the intake and no change in the RPMs. I know I keep harping on this but it sounds like air restriction of some sort.

Brian
 
2broke2ride said:
I agree, and I've been through the ignition at least as many times as the carb. I've never experienced a bad condenser so I don't know how that would act. I could start swapping ignition parts with my 380 if this carb turns out to be a no go.
Click to expand...
Re-reading your post it sounds possessed. I've rebuilt quite a few saws tearing them completely down and making new gaskets as you've said and replacing seals and everything else. I'd probably tear it all the way back down if it were me and start over. Usually it turns out being something simple. 99% of the time I rebuild a carb the saw runs great or if a complete tear down. I've never had one act like what your describing. Only issue I've had is from a bad ground. I know others with condensers gone bad where their saw acted really whacky...

It can be frustrating at times yet also be something simple overlooked. Hopefully soon you will get it going. I've got a low hour 440 and it's a great old saw i like running. I prefer the top tank saws myself over the front tanks although I do like running the super 250. I've got one other 440 with an experimental governor I believe on it I need to get going just to see if it works . Haven't seen any other 440 saws yet with this contraption on it only a couple 380 saws with one similar.

I also keep a spare test carb around for a quick check if I suspect the carb being the problem to quickly eliminate it. Comes in right handy. Anyway you will figure it out soon. You've given me inspiration to work on my other 440 now I forgot about it sitting up on the top shelf. I'm anxious to see that governor work if it does and just how it will run.. Good luck on your saw... Keep us posted... I don't post much anymore but drop in from time to time. Other hobbies take up a lot of time as well plus it motorcycle riding season...

Sent from my SM-T330NU using Tapatalk
 
I wished I had time to ride myself Nickolas. My bike thinks I have forgotten about it. I agree with you. Maybe tare it down and double check everything as you assemble it. I bet something will pop up and you will find your problem. I know you don't want to go threw all that but I think at this point it is the only thing left to do. If you want to send it to me I will see if I can get it running properly if you get to that point.

Brian

Good Luck and hope you find your problem soon.
 
I'm gonna give the whole story on this saw so it's out there. This is going to be long.

I bought the saw July last year as a non runner. I got it running by dressing the points and it ran pretty ok considering. I could take it out and cut with it but it ran kind or erratic, didn't really wanna idle etc. So I figured I should start with changing the crank seals. I tore it down and then ended up not doing anything with it till about a month ago. Finally put crank seals in it and went through the carb too at that time. Then I couldn't get it to run right. Would start hard and flood out to the point that fuel would be running out of the exhaust. Took the carb back apart and found the metering lever way too high. Set it to spec and put it back together then all of this wierd no acceleration stuff started. So thinking I had an air leak I started pressure testing. Found the reed plate gaskets leaking, fixed that and no change, pressure test again and found I had messed up a crankseal so replaced it again, no change. So I went back into carb, this time I put a kit in it from sugar creek. Now I can hardly get it pop so I'm back in the carb again. It's soaking as we speak waiting on the Welch plugs from Mark. It seems the more I mess with it the worse it gets.


Brian, I agree that it seems like an airflow issue to me too but how? And why? It all started when I messed with the metering lever in the carb.
 

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