Question for Joe Lucia - 1972 LT1 Alternator Pulley

[Greg Y.]

Hi Joe, I am trying to find the correct alternator pulley for a 1972 LT1, could you please let me know what is the correct part number for this pulley? Thank you! Greg

[Joe L.]

Re: Question for Joe Lucia - 1972 LT1 Alternator Pulley

Hi Joe, I am trying to find the correct alternator pulley for a 1972 LT1, could you please let me know what is the correct part number for this pulley? Thank you! Greg

Greg------


Assuming the car doesn't have C-60, the original pulley was GM #1970831 but it's long-since discontinued. GM #3844100 replaced it and will work but it's discontinued too.

[Greg Y.]

Re: Question for Joe Lucia - 1972 LT1 Alternator Pulley

Thanks Joe! I have a C60 LT1 as well, I was not aware that they are different pulley's. Could you provide the correct pulley number for that application? Thanks! Greg

[Joe L.]

Re: Question for Joe Lucia - 1972 LT1 Alternator Pulley

Thanks Joe! I have a C60 LT1 as well, I was not aware that they are different pulley's. Could you provide the correct pulley number for that application? Thanks! Greg

Greg------


With C-60 it was either 1949356 or 1949357. I can't say, for sure, which one as I have conflicting application information. These were nearly identical configuration pulleys except for OD. The 1949356 is 2.62" OD; the 1949357 is 2.91" OD.

The two are pictured below. Note the identifying stamped "6" and "7":



DSCN2944.jpgDSCN2945.jpgDSCN2946.jpgDSCN2947.jpg


Of the two pulleys, my opinion would be that it was the 1949357 that was originally used but it's also possible it was the 1949356. The 1949347 was actually discontinued from SERVICE in November, 1966. However, it was used in PRODUCTION long after that time. In fact, my 1969 was originally equipped with one.

[Greg Y.]

Re: Question for Joe Lucia - 1972 LT1 Alternator Pulley

Wow Joe, thanks for your excellent answer and the great pictures! This is very helpful, now I know that both of my cars have the wrong alternator pulley on them. Do you have the OD of the 1970831/3844100?

[Joe L.]

Re: Question for Joe Lucia - 1972 LT1 Alternator Pulley

Wow Joe, thanks for your excellent answer and the great pictures! This is very helpful, now I know that both of my cars have the wrong alternator pulley on them. Do you have the OD of the 1970831/384100?

Greg------


The GM #1970831 was 3-3/16" OD. It was a zinc plated, machined steel pulley and not a stamped steel type like the above-described.

I have heard that some LT-1 with C-60 have been found with machined steel pulleys. If so, my opinion would be that either these were a factory mistake (but, still an original configuration for the so-involved cars) or a replacement that occurred somewhere along the way. Rebuilders often supply new machined steel pulleys with some of the better quality rebuilds.

[David L.]

Re: Question for Joe Lucia - 1972 LT1 Alternator Pulley

The 1970831 pulley has an O.D. of 3 3/16" and an I.D. (around the attaching nut) of 1 13/32".
The 3844100 pulley has an O.D. of 3 3 16" and an I.D. (around the attaching nut) of 1 5/8" .

The 1970 Corvette AIM lists alternator pulley # 1949356 for models with 350 engine and C60 option. I do not have a 1972 Corvette AIM.

Dave

[Greg Y.]

Re: Question for Joe Lucia - 1972 LT1 Alternator Pulley

Thanks Dave!

[Joe L.]

Re: Question for Joe Lucia - 1972 LT1 Alternator Pulley

Wow Joe, thanks for your excellent answer and the great pictures! This is very helpful, now I know that both of my cars have the wrong alternator pulley on them. Do you have the OD of the 1970831/3844100?

Greg------


By the way, can you tell me the part numbers stamped on your waterpump pulley and crankshaft pulley? This may figure into this, too.