what is the correct dia. for 837 alt deep pulley

[deuce-less]

trying to match up the correct deep groove pulley for a 69 L-78 nova 837 alternator....

i have two, one is approx. 3 3/16 dia the other is 3 9/16 dia. inches, which one, if either is correct for the application?

thx, alan http://www.yenko.net/ubbthreads/images/graemlins/smile.gif

[Mr70]

I have two original 837's here,and they both have the 3-3/16" OD pulley.

[deuce-less]

thx for the quick and accurate response http://www.yenko.net/ubbthreads/images/graemlins/smile.gif

[3macs1]

[ QUOTE ]
trying to match up the correct deep groove pulley for a 69 L-78 nova 837 alternator....

i have two, one is approx. 3 3/16 dia the other is 3 9/16 dia. inches, which one, if either is correct for the application?

thx, alan http://www.yenko.net/ubbthreads/images/graemlins/smile.gif

[/ QUOTE ]

I am glad you asked this question. I have some Nos 3 9/16 ones but have no idea what they fit. No part number on them like I have seen on some and the strange part is they have a 9/16" bore not 5/8"
Any ideas?? I thought I bought them for 66 l-72 about 27-28 years ago but am not sure
http://i65.photobucket.com/albums/h215/JoesCars/100_3229.jpg

[Keith Tedford]

Try 3770245 Group 1.062 '67-'68 Z/28. May also be the same pulley on early solid lifter Chevies.

[3macs1]

Hi Keith:
Do you mean that alt pulley was used with the 2 groove water pump pulley you quoted the part number for??
Let me know
Thanks Joe

[Keith Tedford]

I was relaying information given to me. No guarantee that it is correct. I shouldn't be assuming anything. You know what that does. http://www.yenko.net/ubbthreads/images/graemlins/frown.gif Other than the OD, it seems to be the same as the later small diameter pulley. They should interchange if you wanted to reduce alternator speed.

[3macs1]

Understand Keith. It is the 9/16 bore throwing me.I thought the GM alts were 5/8 bore but have not checked one in many years.