Topic: 38A or 42A Alternator

[jwc66k]

Comment on the HiPo alternators. They had larger diameter pulleys, I reckon that may have something to do with them being a higher output?
I don't understand electronics, but worth mentioning.

The larger diameter pulley on the standard alternator used on 63 thru 67 Ford cars with the 289 High Performance engines was to lower the RPM at the alternator because the 289 HP engines were capable of sustained revolutions well over 6,000 RPM. It was a method to increase alternator bearing life too.
Jim

[J_Speegle]

Went through my copies of buildsheets for 65 and offer the following you'll notice that I included the DSO and extension (if printed) to respond to sglbbs' focus on those

Hopefully the following is usable in the study and discussion

Plant -Eng-Alt-----Battery---DSO----Ext-   BS Date
5R-----A---Blank --Blank-----?-------Blank   16M
5T-----C---Blank   --Blank-----95 -----Blank   07R
5T-----K---Blank   --Blank-----13 -----Blank   12R
5T-----C---Blank   --Blank-----95 -----Blank   21R
5T-----C---Blank   --D----------26 -----Blank   07S
5T-----K---Blank  ---A--------- 11 -----Blank   13S
5T-----C---Blank  ---D---------15 -----Blank   18S
5T-----C---Blank   --D--------- 12 -----Blank   21S
5T-----C---Blank   --Blank -----95 -----Blank   08U
5T-----C---Blank   --Blank -----24 -----Blank   26U
5T-----C---Blank   --Blank -----24 -----Blank   26U
5T-----T---Blank   --Blank -----21 -----Blank   28U
5T-----C---Blank   --D ---------22   ---Blank    11V
5?-----C---Blank   --A ---------? ---------?         ? (Carried a 174042 VIN)

[J_Speegle]

And for 66 from buildsheets. Convertibles are noted this time just in case that might have made a difference which it appears not have had.

Plant -Eng---Alt-----Battery-   DSO-   Ext-   BS Date
6T-----A-----Blank-----1----------18   Blank   27J
6T-----K-----8---------1----------75   Blank   07K
6T08   K-----8---------1   ----------?   ?        22K
6T-----A-----Blank-----1----------21   Blank   25K
6T-----A-----Blank-----1----------21   Blank   25K
6T-----A-----Blank-----1----------21   Blank   25K
6T08   T-----Blank   ---1----------15   Blank   05L
6T-----K-----8----------1----------14   Blank   10L
6T-----A-----Blank-----1----------22   Blank   02M
6T-----T-----Blank-----1----------15   Blank   04M
6R-----K-----8---------1----------71   2611   18M   
6T-----A-----Blank-----1----------11   1514   29A
6T-----C-----Blank-----1----------22   Blank   02B
6T-----C-----Blank-----1----------37   Blank   03B
6T-----A-----Blank-----1----------21   Blank   01D
6T08   C-----Blank-----1--------- 24   Blank   04D
6T-----C-----Blank-----1----------21   Blank   15D
6F-----K-----8----------2----------35   Blank   26D
6T08   T-----Blank   ---1----------13   Blank   10E
6T-----C-----Blank-----1----------17   Blank   13E

[T_Kaminski]

The larger diameter pulley on the standard alternator used on 63 thru 67 Ford cars with the 289 High Performance engines was to lower the RPM at the alternator because the 289 HP engines were capable of sustained revolutions well over 6,000 RPM. It was a method to increase alternator bearing life too.
Jim

From a technical standpoint, use of the 42A alternator in Hi-Po applications would make sense.  The 38A may have proved inadequate to charge the battery at idle or normal driving, due to the lower RPM ratio.