Johnson Motor

[vtflatlander]

What does RDSL stand for on a 1963 Johnson 40 HP motor. I know it is the model number but what does it stand for.

 

[DaleH]

Up to about 1970, Johnson OB model numbers were two or three letters and a two digit number coding. Motors after 1960 of the 'RD' series were based on a 43.9 cu-in. block. The 'S' may be a production run code, useful for ordering parts. Guessing that the 'L' may be for long shaft, but this is all I can find.

Looks like we need Pappy to chime in here for the absolute answer ...

 

[Pappy]

Good job, Dale! Right on the money.
The "S" meant that it had the newly modified lower crank seal in it. Prior to the "S" models there was a high rate of failure although most were repaired one way or another.