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Old 04/22/2006, 07:02 AM   #1
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Location: Ridgecrest, Ca
Joined: Mar 03
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428 Cobra Jet Exhaust

I put some information on original exhaust in a different post, and have copied it here with some pictures for anyone interested in reading it. I became motivated to write something here after seeing Bob Teets 428 HCS at Knott Berry Farm a couple of weeks ago and was surprised when I saw that it still retained ALL the original exhaust components. How COOL is that.

The exhaust for Cobra Jet cars is specific to 428 CJs and was not used on any other 1968 Mustang except for GT500KRs. The entire system for a CJ car uses 2.25-inch pipes for the H-pipe, resonators, and tail-pipes. The muffler and tail pipe construction are also different than other dual-exhaust cars that use the 2-inch pipes. Below describes the differences and similarities of the two systems (Cobra Jet and non-Cobra Jet such as 302 GT, 390 GT, GT350 Shelbys, and GT500 Shelbys).

H-Pipe: Similar for both systems. Cobra Jet pipe is 2.25-inch and non-Cobra Jet is 2-inch.

Resonator Pipes: Similar for both systems. Cobra Jet pipe is 2.25-inch and non-Cobra Jet is 2-inch. Both have double-hump resonators. The 1969 2.25-inch resonators are triple-hump and are not correct for 1968. Arvin was the original subcontractor to Ford for the exhaust systems and made a run of replacement resonator pipes that sometimes show up, but they are triple-hump. Because the pipes tended to rust and the resonators did not, you can sometimes take the resonators from a rusted system and splice them into replacement (repro) pipes and have them turn out pretty good.

Muffler: The 2-inch muffler is a C8ZA-5230-C. It has a FoMoCo in a rectangle stamped into the muffler casing along with the part number and date. The 2.25-inch muffler is an ED-C8ZA-5230-E. . It has a Ford in an oval stamped into the muffler casing along with the part number and date. Both of these mufflers are very hard to find and getting a good date is even harder. You can enlarge the 2-inch muffler to 2.25-inch with some creative welding, but you still have the wrong part number.

Tail Pipes: The 2-inch tail pipes and tips are two separate items. The chrome quad-tips slide onto the 2-inch pipe and is held in place by a clamp. The 2.25-inch tail pipe and quad tip are one welded assembly and have no clamp to hold it together. Two inch pipes and tips are not too hard to find. 2.25-inch is nearly impossible, but you can do a reasonable job of welding it up.

Hangers: All of the hanging hardware for 2-inch and 2.25-inch is the same.

Clamps: Three types of clamps are used. Saddle, band, and horseshoe. The horseshoe clamp is only used on the 2-inch system to hold the tail pipe and tip together. The saddle clamps are used on the h-pipe to resonator pipes (2), resonator pipes to muffler (2), and tail pipes to muffler (2). The band clamps (2) are used to hold the tail pipes to the J-hook hanger. 2-inch systems used 2-inch saddle clamps, but 2.25-inch systems used 2.125-inch and 2.25-inch saddle clamps. The orientation of the clamps is remarkably consistent from car to car on cars built at the Metuchen plant. I canít comment on San Jose CJs though.

Misc: All the exhaust systems had a tab and notch design for assembling the systems. I believe the systems were assembled on the ground and swung up into the cars as entire assemblies before the rear ends were installed.

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