Products to Compare (max of 3)
Compare These Parts
Talk to the Experts. Call 800.979.0122, 7am-10pm, everyday.
Customer Service
Since 1952
  • Expert Tech Support
  • Huge Inventory
  • Fast Shipping
Add to Cart
Holley 20-131 R4 Compressor LS Accessory Drive AC, PS, Alt Bracket Kit
Holley 20-131 R4 Compressor LS Accessory Drive AC, PS, Alt Bracket Kit

Holley 20-131 R4 Compressor LS Accessory Drive AC, PS, Alt Bracket Kit

0 Reviews | 0 Answered Questions
In Stock
Ships FREE
Holley 20-131 R4 Compressor LS Accessory Drive AC, PS, Alt Bracket Kit
Holley 20-131 R4 Compressor LS Accessory Drive AC, PS, Alt Bracket Kit
Zoomed In Image
Part # 42520131
Add to Cart
Call to Order
Add to Buildlist

Videos & Articles

Important Messages:

  • Get FREE shipping when your order includes this item and exceeds $99! Ground shipping only in the contiguous US.


GTIN Code:
MFG. Part #:
Sold in Quantity:
Hardware Included:


These accessory drive brackets from Holley are great when swapping a GM LS engine into a muscle car, truck, hot rod or other vehicle. These brackets were designed to deliver a factory style appearance, correct belt alignment, and factory stability.  Holleys kits supply the required brackets and hardware needed for installation.

To determine correct application, these three easy steps will help get you going:

  • Step one is to determine your belt alignment based on your crank Pulley position on the engine you have.
  • Step two is to choose the Holley accessory drive brackets that you need (A/C, Alt & P/S or both).
  • Step three is to see which Holley installation kit your set–up requires to line up your accessories with your crank Pulley position. An application specific installation kit (part # 425-211, 425-212, or 425-213) is REQUIRED for most applications.

Note: When referring to guide links below, keep in mind that part numbers shown are MFG numbers without "425" prefix.

Fitment and Required Components Guide for 20-131 Bracket Kit (PDF)  

Assembly Instructions for Holley 20-131 Accessory Drive Kit (PDF)   

Item Details

This bracket kit REQUIRES an additional installation kit for assembly
(Part 425-211, 425-212, OR 425-213, see Fitment Guide for the
correct installation kit for your application).


Holley's kits supply the required brackets and hardware needed for installation, but allow you to choose the source for supplemental accessories and components that are often already on the donor engine or host vehicle. Whether sourcing from the salvage yard, the local auto parts store, your GM parts dealer, or Holley, you pick the accessories that match your needs and budget!

Installation Notes:
Works with R4 A/C compressor; Requires application specific installation kit

Key Features:

  • The most cost effective LS bracket solution on the market!
  • Universal brackets fit virtually all common LS engines regardless of water pump and harmonic balancer offsets reducing cost and complexity compared to competitive products
  • Simple, dedicated installation kits allow easy fitment to Corvette, F–Body or Truck drive offsets
  • Utilizes commonly available and affordable GM alternators, power steering pumps and A/C compressors
  • A/C brackets position the compressor high above the cross–member but below the hood line for easy installation and great looks
  • A/C brackets are also a bolt on solution to relocate A/C compressor on engines using a GM Corvette accessory drive system
  • A/C bracket accepts GM R4 compressor
  • OEM quality natural finish die castings for clean looks and durability. Can be polished, coated, painted or plated.
  • OEM spec flanged head hardware included to match your factory LS engine hardware
  • Complete accessory drive kits include all components and accessories
  • Ideal for crate engines, take out motors and engine builders!


Some parts are not legal for use in California or other states with similar laws/regulations

Related Products

More Like This


Q & A

Videos & Articles
  • Visit the Toolbox

    The Toolbox is Speedway Motors' hub for professionally written articles.

  • Pat talks about our red solid core spark plug wire and rajah ends.
  • Looking for an easy performance upgrade to your ignition system? MSD's line of Ignition Control Boxes offer extreme improvements to drivability and high rpm applications. Here's a look at the differences between the 6 series line-up.
  • Get the best out of your ignition system! Here we take a look at some of the differences between factory plug wires and the improvements you'll receive with a quality set of aftermarket performance wires.
  • Speedway Motors employee Tim M. Decided to take us along as he revives his 241 "Baby Hemi". In this installment, Tim walks us through updating the old wire covers with a nice set of Offenhauser Finned Wire Covers.
    Learn More

You May Also Like