when did the Motorcraft starter "style" change?

billd wrote: Thanks - looks like we're getting it narrowed down nicely! You can't go by those vehicles with starters that have been changed for rebuilts as the rebuilt may be either style and still fit..........

Yes, and I wonder if the newer style has any advantages?

I know this thread is way old, but I thought I'd add this nevertheless. While reading up on the defective starter of my 1978 AMX I found an article [1] of Hemmings Motor News from January 2010 where it says:

"In 1977, Ford made two small physical changes in the starter, which did not affect the interchangeability of the earlier units. First, they moved the battery connection from a copper post on the side of the starter case to a two-part female eyelet terminal on the rear plate of the starter. This was done to make room in the case for more windings, which results in a slightly higher torque value on late model units. [...]"

[1] https://www.hemmings.com/magazine/hmn/2010/01/Ford-AMC-Motorcraft-Starters/2602681. - https://www.hemmings.com/magazine/hmn/2010/01/Ford-AMC-Motorcraft-Starters/2602681.html


Edited by Tobias - Apr/23/2017 at 10:51am

I read up on this in the 1978 AMC Technical Service Manual.

Chapter 1F: Starting System
"[...] During the 1977 model year, a revised starter motor was put into production. This revised motor is carry-over for the 1978 model year. Briefly, the revisions included a simplified brush guide and spring assembly, revised drive yoke clamp and relocation of the input terminal onto the end plate at the brush end.
Three different starter motors are listed in the Specifications chart at the end of this chapter. The small-diameter motor is used on four-cylinder engines. The standard performance large-diameter motor is used on all six-cylinder engines and on 304 CID eight-cylinder engines. The high-performance motor is used on 360 CID eight-cylinder engines. The performance level of the two large-diameter motors is determined by the cross-sectional area of the field coils."

Identification
"At the time of manufacture, the starter motor identification code is stamped on the frame adjacent to the American Motors Part Number. The date is decoded as follows:

• Year (7—1977, 8—1978)
• Month (A—Jan., B—Feb.)
• Week (A—first week in month, B—second week)"

From the Starter Motor Specifications chart:
Small-diameter motor: 4 inches frame diameter; No Load Test: 69 amps, 6709-10843 rpm
Standard performance large-diameter motor: 4.5 inches frame diameter; No Load Test: 67 amps, 7380-9356 rpm
High-performance large-diameter motor: 4.5 inches frame diameter; No Load Test: 77 amps, 8900-9600 rpm