Rebate

Holley 20-242BK BBC Mid-Mount Complete Accessory System, Black

Rebate

#42520-242BK

Holley 20-242BK BBC Mid-Mount Complete Accessory System, Black

Name: Holley 20-242BK BBC Mid-Mount Complete Accessory System, Black
Brand: Holley
SKU: 42520-242BK
Price: 1978.95 USD
Availability: InStock

Write a Review

Ask a Question

$1,978.95

/kit

Factory Shipped

$2,199.95

Save $221.00

Quantity

Need Help? Call to Order

Add to a list

Select an engine to verify Fitment

Select Engine

Product Summary

Universal Fit, Hardware Included

Rebates Available

See rebate details

See more details

Key Specs

MFG. Part #	20-242BK
Brand	Holley

See more specs

Need To Know

Need help?

855.313.9176

View the Help Center

Quick and Easy Returns

Return Policy

Holley 20-242BK Details

Holley's Mid-Mount accessory drives are now available for your big block Chevrolet engines! The revolutionary system does what no other accessory bracket system has done… GETS RID OF THE BRACKETS!

The Mid-Mount complete accessory system has all accessories pulled in tighter than other accessory drives. At the heart of the system is a "bracketless" design (Patent Pending), where the accessories bolt directly to the water pump for a clean, integrated form. The design offers superb engine visibility to show off your horsepower, not your accessories. The Holley designed alternator is just as innovative. This premium alternator utilizes 6-phase technology as found on the C7 Corvette. The water pump also shares its design efficiencies with that of the C7 Corvette. The compact and reliable SD7 A/C compressor and Type II P/S pump with baffled reservoir are also integrated.

The water pump design incorporates optional side or top heater ports. The top thermostat bypass and heater ports are recessed into the manifold. So if you don't need them, you don't see them!

When we say "complete", we mean complete. The Mid-mount system comes with everything you need. All accessories are included; the water pump, A/C compressor, Alternator, and P/S pump with reservoir. All pulleys and the belt are supplied. Even A/C line adapter, heater hose adapters, power steering to -6 AN hardline, and the alternator plug/harness are included. Easy assembly was a priority during the entire development of this accessory solution. Color graphical instructions walk you through every step of the ultra-easy installation.

Features:

The Mid-Mount complete accessory system has all accessories pulled in tighter than other accessory drives.
Bracketless accessory mounting with ultra-easy assembly
O-ring seal to engine
Hidden thermostat bypass and heater hose ports with NPT line adapters included
LT1 style premium alternator
LT1 style water pump design
Compact SD7 A/C compressor with line adapter included
Type II power steering pump with baffled reservoir
P/S adapter hardline to AN -6 adapter included
OE pulley ratios for optimal accessory performance
Available in natural and black finishes
Billet alternator, tensioner, and compressor pulley covers

Charts

Installation Instructions (PDF)

Rebates

Holley Heritage Sale 10% off Select Parts

Holley Heritage 10% Off Select Parts Sale, running from July 6, 2026, through July 31, 2026. For a limited time, customers can save 10% off on select parts, making it the perfect opportunity to upgrade your vehicle with high-quality components. Sale prices apply to purchases made during the sale period only. No rainchecks or exceptions will be provided. This sale cannot be combined with any other offers, discounts, or promotions.

Guides & Documents

Serpentine Conversion Kits Installation Instructions (42520-242BK)

Holley 20-242BK Specifications

KEY SPECS
MFG. Part #	20-242BK
Brand	Holley

GENERAL
Hardware Included	Yes
Sold in Quantity	Kit
GTIN Code	090127072813

Ratings & Reviews

Be the first to write a review.

Questions & Answers

Be the first to ask a question.

Fitment

1965 Chevy Bel Air

396 Chevy Big Block V8

1966-1969 Chevy Bel Air

396 Chevy Big Block V8
427 Chevy Big Block V8

1970-1972 Chevy Bel Air

402 Chevy Big Block V8
454 Chevy Big Block V8

1973-1975 Chevy Bel Air

454 Chevy Big Block V8

1965 Chevy Biscayne

396 Chevy Big Block V8

1966-1969 Chevy Biscayne

396 Chevy Big Block V8
427 Chevy Big Block V8

1970-1972 Chevy Biscayne

402 Chevy Big Block V8
454 Chevy Big Block V8

1969 Chevy Brookwood

396 Chevy Big Block V8
427 Chevy Big Block V8

1970-1972 Chevy Brookwood

402 Chevy Big Block V8
454 Chevy Big Block V8

1969 Chevy C10

396 Chevy Big Block V8

1970-1972 Chevy C10

402 Chevy Big Block V8

1973-1979 Chevy C10

454 Chevy Big Block V8

1968-1969 Chevy C10 Suburban

396 Chevy Big Block V8

1970-1972 Chevy C10 Suburban

402 Chevy Big Block V8

1973-1979 Chevy C10 Suburban

454 Chevy Big Block V8

1988 Chevy C15

454 Chevy Big Block V8

1990 Chevy C1500

454 Chevy Big Block V8

1991 Chevy C1500

Chevy Big Block V8 Gen 5 454 L19
Chevy Big Block V8 Mark IV 454 LS5

1992-1993 Chevy C1500

454 Chevy Big Block V8

1968-1969 Chevy C20

396 Chevy Big Block V8

1970-1972 Chevy C20

402 Chevy Big Block V8

1973-1987 Chevy C20

454 Chevy Big Block V8

1968-1969 Chevy C20 Suburban

396 Chevy Big Block V8

1970-1972 Chevy C20 Suburban

402 Chevy Big Block V8

1973-1986 Chevy C20 Suburban

454 Chevy Big Block V8

1991 Chevy C2500

Chevy Big Block V8 Mark IV 454 L19
Chevy Big Block V8 Gen 5 454 L19

1992-1995 Chevy C2500

454 Chevy Big Block V8

1996-1997 Chevy C2500

Chevy Big Block V8 Gen 5 454 L19
Chevy Big Block V8 Gen 6 ZZ454 454

1992-1995 Chevy C2500 Suburban

454 Chevy Big Block V8

1996-1997 Chevy C2500 Suburban

Chevy Big Block V8 Gen 5 454 L19
Chevy Big Block V8 Gen 6 ZZ454 454

1968-1969 Chevy C30

396 Chevy Big Block V8

1970-1972 Chevy C30

402 Chevy Big Block V8

1973-1986 Chevy C30

454 Chevy Big Block V8

1988-1990 Chevy C3500

454 Chevy Big Block V8

1991 Chevy C3500

Chevy Big Block V8 Mark IV 454 L19
Chevy Big Block V8 Gen 5 454 L19

1992-1995 Chevy C3500

454 Chevy Big Block V8

1996-1997 Chevy C3500

Chevy Big Block V8 Gen 5 454 L19
Chevy Big Block V8 Gen 6 ZZ454 454

1967 Chevy Camaro

Chevy Big Block V8 Mark IV 396 L35
Chevy Big Block V8 Mark IV 396 L78

1968-1969 Chevy Camaro

Chevy Big Block V8 Mark IV 396 L34
Chevy Big Block V8 Mark IV 396 L35
Chevy Big Block V8 Mark IV 396 L78
427 Chevy Big Block V8

1970-1972 Chevy Camaro

402 Chevy Big Block V8

1966-1969 Chevy Caprice

396 Chevy Big Block V8
427 Chevy Big Block V8

1970-1972 Chevy Caprice

402 Chevy Big Block V8
454 Chevy Big Block V8

1973-1976 Chevy Caprice

454 Chevy Big Block V8

1965-1969 Chevy Chevelle

396 Chevy Big Block V8

1970-1972 Chevy Chevelle

402 Chevy Big Block V8
454 Chevy Big Block V8

1973 Chevy Chevelle

454 Chevy Big Block V8

1968 Chevy Chevy II

396 Chevy Big Block V8

1965 Chevy Corvette

396 Chevy Big Block V8

1966-1969 Chevy Corvette

427 Chevy Big Block V8

1970-1974 Chevy Corvette

454 Chevy Big Block V8

1966-1969 Chevy El Camino

396 Chevy Big Block V8

1970-1972 Chevy El Camino

402 Chevy Big Block V8
454 Chevy Big Block V8

1973-1975 Chevy El Camino

454 Chevy Big Block V8

1969 Chevy Estate

396 Chevy Big Block V8
427 Chevy Big Block V8

1970 Chevy Estate

402 Chevy Big Block V8
454 Chevy Big Block V8

1996-2000 Chevy Express 2500

Chevy Big Block V8 Gen 5 454 L19
Chevy Big Block V8 Gen 6 ZZ454 454

1996-2000 Chevy Express 3500

Chevy Big Block V8 Gen 5 454 L19
Chevy Big Block V8 Gen 6 ZZ454 454

1988-1990 Chevy G30

454 Chevy Big Block V8

1991 Chevy G30

Chevy Big Block V8 Mark IV 454 L19
Chevy Big Block V8 Gen 5 454 L19

1992-1995 Chevy G30

454 Chevy Big Block V8

1996 Chevy G30

Chevy Big Block V8 Gen 5 454 L19
Chevy Big Block V8 Gen 6 ZZ454 454

1965 Chevy Impala

396 Chevy Big Block V8

1966-1969 Chevy Impala

396 Chevy Big Block V8
427 Chevy Big Block V8

1970-1972 Chevy Impala

402 Chevy Big Block V8
454 Chevy Big Block V8

1973-1976 Chevy Impala

454 Chevy Big Block V8

1969 Chevy K10

396 Chevy Big Block V8

1970-1972 Chevy K10

402 Chevy Big Block V8

1973-1974 Chevy K10

454 Chevy Big Block V8

1968-1969 Chevy K10 Suburban

396 Chevy Big Block V8

1970-1972 Chevy K10 Suburban

402 Chevy Big Block V8

1973-1974 Chevy K10 Suburban

454 Chevy Big Block V8

1968-1969 Chevy K20

396 Chevy Big Block V8

1970-1972 Chevy K20

402 Chevy Big Block V8

1973-1974 Chevy K20

454 Chevy Big Block V8

1968-1969 Chevy K20 Suburban

396 Chevy Big Block V8

1970-1972 Chevy K20 Suburban

402 Chevy Big Block V8

1973-1974 Chevy K20 Suburban

454 Chevy Big Block V8

1985 Chevy K20 Suburban

454 Chevy Big Block V8

1991 Chevy K2500

Chevy Big Block V8 Mark IV 454 L19
Chevy Big Block V8 Gen 5 454 L19

1992-1995 Chevy K2500

454 Chevy Big Block V8

1996-1997 Chevy K2500

Chevy Big Block V8 Gen 5 454 L19
Chevy Big Block V8 Gen 6 ZZ454 454

1992-1995 Chevy K2500 Suburban

454 Chevy Big Block V8

1996-1997 Chevy K2500 Suburban

Chevy Big Block V8 Gen 5 454 L19
Chevy Big Block V8 Gen 6 ZZ454 454

1968-1969 Chevy K30

396 Chevy Big Block V8

1970-1972 Chevy K30

402 Chevy Big Block V8

1977-1986 Chevy K30

454 Chevy Big Block V8

1988-1990 Chevy K3500

454 Chevy Big Block V8

1991 Chevy K3500

Chevy Big Block V8 Mark IV 454 L19
Chevy Big Block V8 Gen 5 454 L19

1992-1995 Chevy K3500

454 Chevy Big Block V8

1996-1997 Chevy K3500

Chevy Big Block V8 Gen 5 454 L19
Chevy Big Block V8 Gen 6 ZZ454 454

1969 Chevy Kingswood

396 Chevy Big Block V8
427 Chevy Big Block V8

1970-1972 Chevy Kingswood

402 Chevy Big Block V8
454 Chevy Big Block V8

1973-1975 Chevy Laguna

454 Chevy Big Block V8

1965-1967 Chevy Malibu

396 Chevy Big Block V8

1973-1975 Chevy Malibu

454 Chevy Big Block V8

1970-1972 Chevy Monte Carlo

402 Chevy Big Block V8
454 Chevy Big Block V8

1973-1975 Chevy Monte Carlo

454 Chevy Big Block V8

1969 Chevy Nova

396 Chevy Big Block V8

1970 Chevy Nova

402 Chevy Big Block V8

1975-1990 Chevy P30

454 Chevy Big Block V8

1991 Chevy P30

Chevy Big Block V8 Gen 5 454 L19
Chevy Big Block V8 Mark IV 454 LS5

1992-1995 Chevy P30

454 Chevy Big Block V8

1996-1997 Chevy P30

Chevy Big Block V8 Gen 5 454 L19
Chevy Big Block V8 Gen 6 ZZ454 454

1972 Chevy P30 Van

402 Chevy Big Block V8

1973-1974 Chevy P30 Van

454 Chevy Big Block V8

1987-1988 Chevy R20

454 Chevy Big Block V8

1987-1988 Chevy R20 Suburban

454 Chevy Big Block V8

1989 Chevy R2500

454 Chevy Big Block V8

1989-1990 Chevy R2500 Suburban

454 Chevy Big Block V8

1991 Chevy R2500 Suburban

Chevy Big Block V8 Mark IV 454 L19
Chevy Big Block V8 Gen 5 454 L19

1987-1988 Chevy R30

454 Chevy Big Block V8

1989-1990 Chevy R3500

454 Chevy Big Block V8

1991 Chevy R3500

Chevy Big Block V8 Mark IV 454 L19
Chevy Big Block V8 Gen 5 454 L19

1969 Chevy Townsman

396 Chevy Big Block V8
427 Chevy Big Block V8

1970-1972 Chevy Townsman

402 Chevy Big Block V8
454 Chevy Big Block V8

1987-1988 Chevy V20 Suburban

454 Chevy Big Block V8

1990 Chevy V2500 Suburban

454 Chevy Big Block V8

1987-1988 Chevy V30

454 Chevy Big Block V8

1989-1990 Chevy V3500

454 Chevy Big Block V8

1991 Chevy V3500

Chevy Big Block V8 Mark IV 454 L19
Chevy Big Block V8 Gen 5 454 L19

1975-1978 GMC C15

454 Chevy Big Block V8

1975-1978 GMC C15 Suburban

454 Chevy Big Block V8

1973-1974 GMC C15/C1500 Pickup

454 Chevy Big Block V8

1973-1974 GMC C15/C1500 Suburban

454 Chevy Big Block V8

1979 GMC C1500

454 Chevy Big Block V8

1979 GMC C1500 Suburban

454 Chevy Big Block V8

1975-1978 GMC C25

454 Chevy Big Block V8

1975-1978 GMC C25 Suburban

454 Chevy Big Block V8

1967-1970 GMC C25/C2500 Pickup

396 Chevy Big Block V8

1971-1972 GMC C25/C2500 Pickup

402 Chevy Big Block V8

1973-1974 GMC C25/C2500 Pickup

454 Chevy Big Block V8

1967-1970 GMC C25/C2500 Suburban

396 Chevy Big Block V8

1971-1972 GMC C25/C2500 Suburban

402 Chevy Big Block V8

1973-1974 GMC C25/C2500 Suburban

454 Chevy Big Block V8

1979-1986 GMC C2500

454 Chevy Big Block V8

1988-1990 GMC C2500

454 Chevy Big Block V8

1991 GMC C2500

Chevy Big Block V8 Mark IV 454 L19
Chevy Big Block V8 Gen 5 454 L19

1992-1995 GMC C2500

454 Chevy Big Block V8

1996-2000 GMC C2500

Chevy Big Block V8 Gen 5 454 L19
Chevy Big Block V8 Gen 6 ZZ454 454

1979-1986 GMC C2500 Suburban

454 Chevy Big Block V8

1992-1995 GMC C2500 Suburban

454 Chevy Big Block V8

1996-1999 GMC C2500 Suburban

Chevy Big Block V8 Gen 5 454 L19
Chevy Big Block V8 Gen 6 ZZ454 454

1975-1978 GMC C35

454 Chevy Big Block V8

1967-1970 GMC C35/C3500 Pickup

396 Chevy Big Block V8

1971-1972 GMC C35/C3500 Pickup

402 Chevy Big Block V8

1979-1986 GMC C3500

454 Chevy Big Block V8

1988-1990 GMC C3500

454 Chevy Big Block V8

1991 GMC C3500

Chevy Big Block V8 Mark IV 454 L19
Chevy Big Block V8 Gen 5 454 L19

1992-1995 GMC C3500

454 Chevy Big Block V8

1996-2000 GMC C3500

Chevy Big Block V8 Gen 5 454 L19
Chevy Big Block V8 Gen 6 ZZ454 454

1967-1970 GMC K25/K2500 Pickup

396 Chevy Big Block V8

1971-1972 GMC K25/K2500 Pickup

402 Chevy Big Block V8

1967-1970 GMC K25/K2500 Suburban

396 Chevy Big Block V8

1971-1972 GMC K25/K2500 Suburban

402 Chevy Big Block V8

1994-1999 GMC K2500 Suburban

Chevy Big Block V8 Gen 5 454 L19
Chevy Big Block V8 Gen 6 ZZ454 454

1977-1978 GMC K35

454 Chevy Big Block V8

1967-1970 GMC K35/K3500 Pickup

396 Chevy Big Block V8

1971-1972 GMC K35/K3500 Pickup

402 Chevy Big Block V8

1979-1986 GMC K3500

454 Chevy Big Block V8

1988-1990 GMC K3500

454 Chevy Big Block V8

1991 GMC K3500

Chevy Big Block V8 Mark IV 454 L19
Chevy Big Block V8 Gen 5 454 L19

1992-1995 GMC K3500

454 Chevy Big Block V8

1996-2000 GMC K3500

Chevy Big Block V8 Gen 5 454 L19
Chevy Big Block V8 Gen 6 ZZ454 454

1987-1989 GMC R2500

454 Chevy Big Block V8

1987-1990 GMC R2500 Suburban

454 Chevy Big Block V8

1991 GMC R2500 Suburban

Chevy Big Block V8 Mark IV 454 L19
Chevy Big Block V8 Gen 5 454 L19

1987-1990 GMC R3500

454 Chevy Big Block V8

1991 GMC R3500

Chevy Big Block V8 Mark IV 454 L19
Chevy Big Block V8 Gen 5 454 L19

1996-2000 GMC Savana 2500

Chevy Big Block V8 Gen 5 454 L19
Chevy Big Block V8 Gen 6 ZZ454 454

1996-2000 GMC Savana 3500

Chevy Big Block V8 Gen 5 454 L19
Chevy Big Block V8 Gen 6 ZZ454 454

1971-1972 GMC Sprint

402 Chevy Big Block V8
454 Chevy Big Block V8

1973-1977 GMC Sprint

454 Chevy Big Block V8

1967 GMC Suburban

396 Chevy Big Block V8
402 Chevy Big Block V8