McCulloch Chain Saws

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I keep thinking about using a Mini Mac or string trimmer engine as an impulse pump so I can test the fuel pump section in a carburetor before putting it back in a saw. Of course that will mean creating a few flanges for saws that get the impulse signal from the mounting flange but that should not be too difficult. I needed to test this one today (Tillotson HT carburetor off a Stihl 880...forgive me McPeople) so I connected a veterinary type syringe to the impulse and pumped back and forth like a madman...it worked and I could demonstrate to myself that the fuel pump was working. Ultimately it worked...off the saw...for the life of me I could not figure out why it would not move fuel on the saw so I pulled the spark plug to make cranking it easier...now it was moving fuel. Replace the spark plug, starts and runs for a few seconds then stops moving fuel again. After several attempts I hear something rattling, it should not do that, so I start to take the muffler off and discover the cylinder was loose. Two screws were gone completely, the other two were loose. At least I finally figured out why it was not generating the impulse signal to run the fuel pump.

I am filing this mostly non-McCulloch report here since more people will see it and I will eventually make my impulse generator out of some piece of McCulloch kit.

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I suppose I am breaking some Federal law by not discarding the syringe after using it but I'll risk it. I use that red oil can filled with mix to prime saws when needed, seemed suitable as a reservoir for this test.

Mark
 
I needed to test this one today (Tillotson HT carburetor off a Stihl 880...forgive me McPeople) so I connected a veterinary type syringe to the impulse and pumped back and forth like a madman...it worked and I could demonstrate to myself that the fuel pump was working.
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I use syringes like these to suck up a thick oil that I use in my wood shop. For your purpose you could even have the spring inside the syringe tube. I think this would work for your purpose. I plan on trying on the next carb. Thanks for the idea. However, I do like the idea of having a dedicated engine mounted to the bench just for this. Anytime I see someone over complicate something by making it gas powered it gives me a warm feeling. At the last Steam engine tractor show a few weeks ago here in Oregon a guy had a 6hp single cylinder hit/miss engine with a four inch belt driving a gearbox that had a pencil sharpener on it and a bunch of pencils for people to sharpen. Bless this guy.
 
Coming up next month,Sept.9,10,11,& 12 will be the 54th annual W.N.Y.Gas & Steam Association Rally in Alexander,N.Y.This is one huge gala consisting of old time steam engines,farm tractors,hit & miss engines,threshing & saw mill demonstrations,daily tractor pulls,etc.I remember going to the very 1st one when I was 9 back in 1967.There were only a few hit & miss engines & I think there was one steam engine running a thresher.This thing has grown to the point that they purchased a 200+ acre farm (one of the buildings I helped construct when I was 23 for the farmers who owned it back in 1981,it was a 50ft.x150 ft pole barn).People come from all over the U.S.The last time I was there I saw one of the tractors we had on our farm & also one of my grandpa's tractors that he bought brand new in 1940,an Allis Chalmers model B.
 
Rpm to high or just right?
Sounds right about at the top edge of perfect to me. A sharp chain in a nice log would tell the tale. I'd say any adjustments either side of where you are will likely just be small ones to accommodate different b/c setups and/or cutting conditions.

Nice job.
 
This followed me home today. It's in pretty fair shape! Spent all it's life over on the Oregon coast then made it over to North Idaho where it's been sitting for many years. Decomp switch is busted and of course the check valve in the fuel cap is mush. There's a little bit of oxidation in the fuel tank but not terrible. It turns over and has compression so I'm hopeful. The things I find cool are the intact muffler guard, the sdc carb and intact front bracket. Will yank yank muffler off tomorrow and have a good look inside. Looking forward to bringing this back to life. Been very busy with fire season hitting hard and early here in north Idaho in July. Haven't been able to touch a single saw until the last day.
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