sc case compression and compression ratio

[rfdmn]

Checked the compression on an 1950 sc I recently acquired. readings varied from 130 to 140 which I thought was even enough however seemed higher than what I would have considered normal. I expected normal numbers to be around 110 to 115. Checked IT manual and didn't find any specs for the sc. Can anyone provide me with any numbers?

 

[oldproudvet]

There really aren't any set numbers, only guidelines, maybe. Way to many variables. The old rule of thumb is with 10% of ea
other. Engine temp makes a difference, cranking speed: hand crank, 6 volt, 12 volt? Are the plugs all out and the throttle wide
open so it can get plenty of air. And of course a high houred engine may exhibit blow by and give 4 lower readings but it still
runs out fine. My gut says your good and carboned up. It probably needs a day pulling an 8' tandom disc, buried to axles. Wear
a cap it'll look like a steamer that's had the fire box open for a while to refuel. The carbs are so basic on those things any
partial throttle is way to rich. The updraft carbs lack a good transition circuit and also a functioning power circuit to do a
good job of metering. They weren't built to idle at shows, parades and tractor rides. Belt work and field work was great, but
pulling a rack around can foul plugs in a hurry on an older engine with just a titch of blowby. My thoughts. It used to be an
annual winter chore to pull heads and decarbon them. My 1914 4 cyl Buick's (carb very similar to the SC) owner's manual has a
neat section about pulling the engine down every winter, reshimming bearings and cleaning carbon. The illustrations show a farm
kitchen, an aproned wife in the background, kids looking on, while dad scrapes the carbon from the head (overhead valve head) on
the kitchen table........

 

[rfdmn]

thanks for the info!!