Difference between 1967 and 1973 alternator on Small block?

[wawarnick]

I have a 1973 340. I got the 70 and later water pump and crank pulleys. I have the 1970 and later alternator bracket with 1967 318 alternator. The alternator and crank pulleys line up, but the alternator not so much. Is there a difference in the alternator mount or pulley on a post 70 small block as opposed to the 69 and below? It looks like if I had a double pulley the outside pulley would probably line up. Thank you.

 

[cudamark]

Pulleys and brackets changed from the '69 and older version to the '70 and up version.....both A/C and non-A/C setups. The alternator pulleys came in a few different diameters and in a single (non-A/C) and double (A/C) version. Usually, the double pulley will work on a single pulley application.

 

[66Valiant528]

If you go to Bouchilons web site you can see that the single groove pulley and double groove pulleys have different centers. The double groove doesn't actually line up with a single groove wp and crank.

 

[Dana67Dart]

Another difference is the older alternator needs a grounded field mechanical voltage regulator, vs the more modern isolated field electronic VR.

Dimentionally the mount locations are the same. The brackets are unique 69 older and 70 newer.

If you have 70 newer and aluminum 70 newer water pump all should line up correctly ( 2 pulley vs 1 pulley there seems to be a slight difference in CL)

post some photos

 

[67Dart273]

So called round back alternators were made from the first ones in ?61? to 69, and then 70 when the same round back design CHANGED to isolated field (3 brush connections)--from 70 to about 72, when it was changed to the modern "square back" design that had the rectangular diode/ heat sink. These, generally, are a better design, and can be used on the older grounded field designs (pre 70) by simply grounding one brush and connect your green wire from the regulator to the remaining brush.

all of these will fit the same engine brackets

No sure about the pulleys, I don't remember a problem.