Hey Guys
I know this is an old thread but thought I would add some info, could be useful.
With the Hitachi D4R Dizzy, the number after the R is just the build year. ie D4R85-16 = 1985. D4R83 = 1983. This number has nothing to do with if it is fitted to a manual or auto. The last number is the vac advance spec but it is not in degrees. for D4R85-16 the 16 is vac advance graph number 16.
The mechanical advance was changed through the years so an 83 may have a different advance graph/map to an 85.
I am running a D4R85-16 in my SC12 supercharged 1966 1275 (with MSD boost retard). Mech advance is as per prev mentioned in this thread. I am at the moment setting up a D4R80-11 (JDM spec i think) in a 1968 1275 and it has factory mech advance figures of:
start @ 700rpm (dizzy rpm)
all in @ 2700rpm (dizzy rpm)
max advance 12.5deg.
I will be leaving the max as is but obviously removing a spring or springs to get all in earlier.
From the looks of it, most of these D4Rs have a very gradual advance curve, most of them are not all in until at least 2,500 dizzy rpm (5,000 engine rpm)
http://newprotest.org/projects/510/dizzy_specs.htmEdit. It appears as though judging by the above link. The final two numbers may also represent a model number that has unique mechanical and vacuum advance. For example a D4R82 seems to come with 3 different mach advance profiles
cheers
Rick