PerTronix 6656S User Manual

Installation Instructions

and Warranty Information

For ’67-’70 390/427/428 Mustang

Part# Application Notes

6656S 67-70 Mustang 390 GT 41, 42
6655S 67-70 Mustang 390/427/428/428CJ C6/C4 39, 41, 42
6654S 67-70 Mustang 390/427/428/428CJ 5spd 39, 41, 48, 49, 50

39 Will not fit standard 390 cylinder head.Head flange is designed for 14 bolt 390 GT cylinder head only.
41 Fits most rack and pinion conversions.
42 Requires JBA power steering ram drop down bracket for use with factory power steering.
43 Not designed for 5 spd trans applications
48 Fits 5 spd w/aftermarket cross member
49 Will not fit factory power ste ring.Fits manual steering. e
50 Fits aluminum Shelby block

Read all instructions carefully before attempting installation.

Rev. 11/05

Installation instructions for P/N 6650 JBA Cat4ward® Headers

1967-1970 Mustang 390/427/428/428CJ

NOTE: Installation of this product requires an adequate workspace, general mechanic’s tools,

general mechanical “know-how” and a reasonable degree of experience. Most auto enthusiasts
with these resources will have little difficulty installing these headers. However, you should
carefully read these instructions before attempting to install these headers. If in doubt, consult a
professional mechanic. (Better to do it now than to get stuck halfway through the installation.)
This part is certified for use on Emission Controlled Vehicles.

By installing your JBA Performance Exhaust product, you indicate that you have read this
document and agree with the following terms.

The Purchaser is responsible for following all installation instructions and safety guidelines
supplied with JBA Performance Exhaust products.

JBA Performance Exhaust assumes no responsibility for damages resulting from improper
operation, misuse, abuse, or lack of responsible care, or any problems resulting from
incompatibility with other manufacturer's products.

Included with your installation instructions is a copy of the product warranty. Please read it
carefully before you begin any work on your vehicle. Should you have any questions about the
warranty policy or installation, please give JBA a call at [phone].

JBA uses sealing beads on all its headers. We have found that when installed correctly the
raised bead around each port increases the pressure exerted on the gasket directly adjacent to
the port and effectively prevents leaking gaskets. It is important when installing the header, to
install all bolts loosely, then tighten evenly to ensure the flat installation of the flange. It is normal
for the flange to be raised off the cylinder head the thickness of the sealing bead.

CAUTION: If you dent the headers during the installation process they are no longer resalable,

ruined and non-returnable. If you have trouble during the installation there is something wrong
with your application or the JBA Header. Call 619.229.7797 x.105 for technical support. These
are very critical fitment headers designed for Mustangs with original spec. chassis.

Things you will need:

• Floor jack

•Jack stands with large bases

•WD40 or equivalent penetrating oil

•Set of wrenches

•Socket set, ratchet and extensions

•Hack saw

•Screw drivers

•Two wood blocks 2x2x3 (2x4 cut)

NOTE: Typically the exhaust pipes in these early vehicles are long gone. These instructions

contemplate the removal of old components and the installation of a new exhaust system by a
competent exhaust shop. Thus if you are replacing conventional headers (which typically exit
under the belly near the transmission) with the JBA Tri-Y’s, and your exhaust pipes are in good
shape, the modifications to be performed by an exhaust shop will be relatively minor. These
instructions cover only the installation of the JBA headers. JBA offers a matching 2 1/2”H-pipe
and 2 1/2” exhaust system for the headers.

H-pipe Part No. 6654H
Exhaust System Part No. 50-2650

1. Place vehicle in a location where the floor is solid and flat, with adequate lighting. Do not
attempt to work on a hot engine. Heat causes metal to expand and makes removal of
fasteners difficult at best. Disconnect the battery cables from the battery. Raise the front
of the vehicle up on to the jack stands to obtain adequate access to the bottom exhaust
flanges. Use large-base jack stands to support the vehicle. Do not rely on the jack!
Block the tires to prevent the vehicle from rolling off the jack stands.

2. Disconnect the spark plug wires by grasping and gently twisting the spark plug wire
boots. Do not pull on the wires! Brush or blow any debris, which may have collected
around the manifolds or spark plugs. This will help prevent foreign matter from entering
the combustion chamber when the manifolds are removed. Spray WD-40 or some type of
penetrating oil on all accessible fasteners and fittings before attempting to remove them.

3. From under the vehicle, unbolt the head pipes from the exhaust manifold and the exhaust
system. Then remove the head pipe.