Piston size

[Brendan1959]

I have picked up a spare motor the piston is stamped Q4Q, do you think that is 40" over?

 

[chrs1961815]

It may or may not be.

I know Hudsons in the 30s and 40s and other cars throughout the years had markings on the top of the pistons. Most of the times it is a manufacturing item, like a letter corresponds to piston size. I have only seen a single letter used, but I have not torn too many engines apart. If you could find out the manufacturer of the pistons, they could probably help you in some way. Btw, I checked google and could not find anything for a code like that.

 

[dave in australia]

It could also be 040, which would indicate .040" oversize. Plenty of engines I've pulled apart have had piston sizes stamped in the top. STD, 020, 040, 060 etc.

 

[kenparker]

I agree with Dave in Australia's comment.

 

[Bob Bidonde]

Measure the cylinder,s diameter about one inch below the deck. 3.875" + 0.040" = 3.92" is a ballpark estimate of the cylinder's diameter for an 0.040" oversize.

 

[JoeCB]

Someone had lost their "0" stamp and substituted the nearest thing "Q"

Joe B

 

[Brendan1959]

The bore measures about 3.913 so that must be 40 over

 

[shew01]

Someone had lost their "0" stamp and substituted the nearest thing "Q"

Joe B

Or, maybe eyesight was so bad the installer could not tell the difference between “O” and “Q”?


Sent from my iPhone using Tapatalk

 

[dansluck]

Standard bore is 3.875 plus .040 is 3.915