Posted by David Sherman [172.71.151.121] on Sunday, December 31, 2023 at 20:11:39 :
We finally got a break in the weather and I got back into that Snow-Cat to totally 100% verify the mechanical timing before I try other things to figure out why it won't start. The question, of course, is how to be sure #1 is at TDC. I didn't trust the one tick mark with paint on the timing pulley, which proved to in fact be nowhere near TDC. Probably just an accidental ding that somebody put a dab of paint on.
But how to tell if #1 is at TDC, when the 1/8 pipe plug over #6 will not come out? I thought maybe I could bend a wire and stick it down the spark plug hole to feel when #1 came up, but I couldn't. But then I remembered I had this dandy little endoscope I bought a few months ago off AliExpress for like $30. It worked like a champ. Not only could I easily see the piston but I could see the condition of at least the top inch or two of the cylinder. With that I could correctly mark the timing pulley, verify that the distributor was pointed at #1 wire when #1 piston was at TDC, and verify that the valves on #1 were closed on the compression stroke at the same time.
That still doesn't tell me why it barely attempts to fire, and why it doesn't feel like it has much compression, but seeing that the tappets are non-rusty, the valves are all going up and down, and the timing is approximately correct, I'll now dig into other stuff before I try to start it again. Compression may just feel weak because the rings are dry, and once it fires up, they'll get oily again and it will be good.
I'm usually old-school, but for $30, this endoscope is a piece of tech I will end up using a lot. Sure beats pulling the head.
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