MSD's standard tach drive for its Tach Drive Distributors is a 3/16" tang drive cable, which works in most applications. For installations requiring the 0.104" square drive (Corvette style), this adapter converts the tang drive to fit all MSD Tach Drive Distributor assemblies. It's included with every MSD Tach Drive Distributor.
Specifications:
- Converts: 3/16in Tang Drive to 0.104in Square Drive
- Compatibility: All MSD Tach Drive Distributor Assemblies
- Category: Tachometer Adapter
- Warranty: Manufacturer's Limited 1 Year Warranty
- Part Number: 8491
FAQ
What does the MSD 8491 adapter do?
It converts a standard 3/16" tang drive to a 0.104" square drive (Corvette style) for tach cable compatibility.
Is this adapter included with MSD distributors?
Yes, it's included with each MSD Tach Drive Distributor.
What distributors does this adapter fit?
All MSD Tach Drive Distributor assemblies.

