Craftsman model 921.166400 air compressor

SOURCE: converting from 220 to 110 volts

Most brands of air comperssors are built to work on either 220 or 110 v. I believe that 220 v compressors are more efficient and draw less current and run cooler.
The more expensive compressors have a switch allowing for voltage selection. Still others will have a wiring diagram printed on the motor allowing voltage change by changing jumpers. Most all of the sears compressors that I have repaired were of single voltage with no other way to change except change motor. Do not worry however, you have the better motor. It is easier to convert the outlet plug to 220 by isolating the circuit and installing a 220 v breaker. enjoy

SOURCE: owners manual ruined. what type of oil do i fill w before use

you should be able to find the manual online if it's available if not Sears would I'm sure be able to tell you.

SOURCE: Craftsman 3.5 hp portable air compressor keeps blowin head gasket

I would say the head or block is warped. Use Majic Marker to cover the mating surfaces , the head can be rubbed on a flat surface like a cast iron table saw to find the high spots, or the head can be rubbed on the block.
Careful work with a good flat file will remove the high spots.
The torque value sounds low even for an aluminum block, you could check with a small engine shop to get their opinion.

SOURCE: Oil capacity for craftsman air compressor circa 1978 model #106..

I have a 2hp craftsman air compessor with a two cylinder pump, Here is the info from my manual as far as oil capacitity:

Remove oil fill plug and slowly add
a compressor oil until it is even with the
top of the oil fill hole. NOTE: Do not
allow oil to be lower than 3/8"
from the top at any time. When filling
the crankcase, the oil flows very slowly
into the pump. If the oil is added too
quickly, it will overflow and appear to
be full. NOTE: Crankcase oil capacity is
approximately 16 fluid ounces.

I buy my compessor oil from Lowes in the tool department. It comes in 16oz and sells for about $3. I wouldnt worry about how many ounces it holds but rather that the oil level is to top of filler hole. Lowes also sells a synthetic oil for about $7 and is recommended for severe conditions (hot / cold / used all day). Good Luck!

SOURCE: I have 12 gal.1hp craftsman mod.921-166400 won,t

I would have to say if you are blowing oil out the crankcase that you have a piston or rings problem