72LT1 lower crank pulley

[Kathy Morris]

Hi all -
Does anyone know the part number for the correct lower crank pulley for a 72 LT1? Is it cast? Is it a double pulley? Diameter of center hole? Any help would be appreciated ASAP.
Thanks in advance!
Kathy

[Joe L.]

Re: 72LT1 lower crank pulley

Kathy------

The 70-72 LT-1 crank pulley was a stamped steel pulley of GM #3858533. It is a 2 groove pulley of 6-5/8" OD. This piece is still available from GM to this very day.

ZR-1's, which were a very limited production performance package which included the LT-1 engine, may have used a cast pulley. There is some disagreement about this. GM says such a pulley was used for these applications but actual empirical evidence seems to indicate the contrary.

[Kathy Morris]

Re: 72LT1 lower crank pulley

Thanks, Joe! Do you have a listing for a lower crank pulley GM #3929697 as far as what application and year?

[Joe L.]

Re: 72LT1 lower crank pulley

Kathy-----

Oh, yes! The GM #3929697 is the cast pulley which GM says was used for the LT-1 engine used as part of 70-72 ZR-1 applications. This is the pulley which some dispute was ever actually used for these applications. Since there were so few of these cars ever built, it's hard to "document" it one way or the other.

I have several NOS examples of the 3929697 pulley in my collection [none for sale] and I've examined them carefully. This pulley would fit an LT-1 engine perfectly and could be used in place of the 3858533. So, it's use in the application that GM says that it was used for is NOT precluded by an inherently incompatible configuration.