[Mgs] Generator pulley size?

Barney Gaylord barneymg at mgaguru.com
Fri Jul 16 10:36:55 MDT 2010


At 08:37 PM 7/15/2010 -0700, Simon Matthews wrote:
>Can anyone tell me the correct diameter for the generator pulley on a '57 MGA?
>....

Yup.  See here: http://mgaguru.com/mgtech/electric/et123.htm

There were four different sizes of generator pulleys for MGA, two in 
sheet metal for the pushrod cars and two in cast iron for the Twin Cam cars.

For pushrod cars, pulley size was reduced (and belt shortened) to 
increase dynamo speed at engine number 17061 (February 1957).
http://mgaguru.com/mgtech/care/csm/mg205.pdf
Early pulley was 3-5/8" diameter.  Later pulley was about 3" diameter.

For Twin Cam, pulley size was reduced (and belt shortened) to 
increase dynamo speed at engine number 272 (September 1958).
http://mgaguru.com/mgtech/care/csm/mg237a.pdf
Early pulley was 4-3/4" diameter.  Later pulley was 4" diameter.

For concours show some of the earlier cars may want to have the 
larger pulley and longer belt.  Otherwise it is a good idea to 
convert the earlier cars to the smaller pulley and shorter belt for 
better charging.


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