PDF engine manuals are available by clicking the images below.  Note these are large files -- allow for download times. 

There are two versions of the 4.107/8 manuals, a 1978 version which may be closer to what we have in our boats, and a later, 1983 version.  Also included is a general Perkins Engine Handbook, which has some interesting info as well.

Perkins 4.107/4.108 - 1978 (8.9 MB)    &  1983 Version (14.5 MB)
   

Perkins Marine Engine Handbook - 1973 (11.6 MB)

Borg-Warner Velvet Drive Transmission -
Installation Manual (1.0 MB)   &  Service Manual (4.7 MB)