Compression
 

Dave,

I got a 120 in a trade and, as my Granny used to say, I am trying to make a silk purse out of a sows ear.

I disassembled the engine completely for inspection and found nothing badly worn except the piston ring which had .014" end gap at TDC and BDC. The piston looked recent and exhibited no rock and had minimal scuffing. Valve face and seats, 100% OK. Unfortunately there is little to no compression.

The test stand run left me in question. I can't seem to get the needle valve mixture the way I like it but the idle is the first problem to contend with.

Idle is way way rich , and not adjustable.(old carburetor design) Pinch test confirmed the mix.

I bypassed the regulator, removed checkvalve - still rich. As a matter of fact, it stalls when my glow driver cuts off. This is with 3 OSF plugs. I substituted the carburetor and housings from another engine and had the same results .

The only cause that I can think of is blow-by.

What do you think?

Thanks for your time,
Al

RE: Compression
 

Not enough compression to keep the plug hot, and making the regulator inop because of blow-by. Might need a new ring, liner and piston, but try a ring first.

RE: Compression
 

Have a ring ordered. will post results.

Thanks

RE: Compression
 

Thank You!