428 Cobra Jet Accessory Drive Belts

This page contains application and service part or engineering number descriptions for the many accessory drive belts used on 428 CJ and SCJ Mustangs. Much of the information listed here has been gleaned from build/broadcast sheets, master parts catalogs, and ongoing discussions with people who work with these parts for a living. Sorry, I don't have any pictures of original belts, but I do have pictures of correct belt routing -- see below.

Most, if not all, of these belts are available in reproduction. Replacements are also usually available from the aftermarket at your favorite local parts store.

Key to abbreviations: "a/c" = air conditioning, "ps" = power steering, "w/" = "with", "w/o" = "without".

There are four basic belt configurations. All include use of an alternator, water pump, and Thermactor (smog) pump. The difference is in whether or not power steering and air conditioning are also present. So, these are the possible pulley combinations:

Alternator (two sheaves), water pump (three sheaves), smog (one sheave), and crankshaft (two sheaves): Two belts on the crankshaft pulley drive the water pump and alternator pulleys. A third belt drives the smog pump pulley from the outermost of the sheaves on the water pump pulley.
Alternator (two sheaves), water pump (three sheaves), smog (one sheave), crankshaft (three sheaves), and ps (one sheave): Two belts on the crankshaft pulley drive the water pump and alternator pulleys. A third belt drives the smog pump pulley from the outermost of the sheaves on the water pump pulley. A fourth belt drives the power steering pulley from the outermost of the sheaves on the crankshaft pulley.
Alternator (two sheaves), water pump (two sheaves), smog (one sheave), crankshaft (three sheaves), and a/c (one sheave and two idlers): Two belts on the crankshaft pulley drive the water pump and alternator pulleys. A third belt drives the smog pump and a/c pulleys from the outermost of the sheaves on the crankshaft pulley.
Alternator (one sheave), water pump (two sheaves), smog (one sheave), crankshaft (three sheaves), ps (one sheave), and a/c (one sheave and two idlers): The innermost belt on the crankshaft pulley drives the inner sheave on the water pump pulley and the alternator pulley. The middle belt on the crankshaft pulley drives the outer sheave on the water pump pulley and power steering pulley. The outer belt on the crankshaft pulley drives the a/c and smog pump pulleys.

Right now I only have one image showing correct belt routing. Others are welcome. I know there are drawings in the engine assembly manuals produced by Osborn Reproductions and pictures in some detailing articles that appeared in Mustang Monthly in July 1990, March 1994, and February 2003.

The tables below list what I've found by analyzing broadcast (build) sheets for CJ and SCJ Mustangs. Service part numbers are from the 1975 Master Parts Catalog. It's possible that your build sheet might list different belt numbers than what I have listed here. I've seen the occasional build sheet with different numbers (though I have no idea why they might be different), but these represent the majority of what I've seen. Note, too, that some Canadian service part numbers are different in the MPC and those part numbers aren't listed here.

Image 1: Belts with power steering and air conditioning

Here are some other images showing how the individual belts in the picture above are routed:

Alternator Belt Routing

Power Steering Belt Routing

Smog Pump-A/C Belt Routing

Air Conditioning Belts

Year	Ink-Stamped Engineering Part Number	Service Part Number
1968, 1969	C8ZE-8620-C	C9PZ-8620-GH
1970	D0ZE-8620-C	C9PZ-8620-GH

Smog Belts (no a/c)

Year	Ink-Stamped Engineering Part Number	Service Part Number
1968, 1969	C6OE-8620-B	C9PZ-8620-F
1968, 1969 (w/ ps)	C5TE-8620-B	C9PZ-8620-F
1970	C5DE-8620-D	C9PZ-8620-D

Power Steering Belts

Year	Ink-Stamped Engineering Part Number	Service Part Number
1968-1970 (w/ a/c)	C6OE-8620-B	C9PZ-8620-F
1968 (w/o a/c)	C8SE-8620-B	C9PZ-8620-GU
1969-1970 (w/o a/c)	C9OE-8620-D	C9PZ-8620-FN

Power steering notes: I've also seen a build sheet code of "6VE A" on a few 1969 cars without air conditioning.

Alternator Belts

Year	Ink-Stamped Engineering Part Number	Service Part Number
1968 (w/o a/c)	C6AE-8620-L	C9PZ-8620-GM
1969, 1970 (w/ a/c)	C6AE-8620-M	C9PZ-8620-T
1968, 1969 (w/o a/c) (before 2/17/69) 1970	C6AE-8620-L	C9PZ-8620-GM
1969 (w/o a/c) (from 2/17/69) 1969, 1970 SCJ	C4AE-8620-H	C9PZ-8620-GK

Alternator notes: The build sheets that I've seen tend to use different codes for alternator belts than those that I've seen listed in the MPC. On build sheets I've seen 4MEA, 6AEB, and 6AEM. 1969 in particular seems to lose some correspondence between the build sheet codes and the engineering part numbers.

Thanks to Bill Upham for the pictures used here.

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