69 Z28 EXHAUST SYSTEM

[ALLZS]

DID ALL NORWOOD & LA CARS BUILT AFTER APRIL GET THE RESONATORS OR WAS IT JUST LA CARS ? THANKS

[al8apex]

I have the Chevy Service Bulletin covering that, I don't think it specifies plant ...

Will dig and post pic of page(s)

EDIT: I have the Service Bulletin on the chambered exhaust fiasco (all part numbers too, pretty cool except does not address the OP question, sorry)

EDIT 2: Looked in a 2nd book and it has an update addressing the date of the resonators, pics coming

[al8apex]

In order:

[ALLZS]

GREAT, NOW WHO MAKES THE BEST FITTING SYSTEM

[X66 714]

Although the question is about Z/28s. I doesn't appear that the SS cars followed the same resonator program. Is that correct?
...Joe

[William]

SS cars regardless of engine were not involved in the resonator recall.

The 1st recall applied to Z/28 L34 & L78 built with chambered as standard equipment. SS 350 & L35 SS were built with the N10 muffler/resonator system as standard equipment and were not part of it. L34 & L78 then reverted to the standard N10 system; Z/28 received the interim muffler only system.

The 2nd recall involved the interim Z/28 system; they now also received the standard N10 system.

One of the car mags back in the day had undercarriage photos of the #3 ZL1 [02D] when new; standard N10 system. There is no reason to assume any BB was built with the interim Z/28 system but I see many incorrectly restored that way.

[firstgenaddict]

Here is an actual recall letter sent to an owner of a 69 Z28 built in LA on the 3rd week of December. It states Dec 4th last day of Chambered and May 2nd last day without resonators.



As an aside... THE dates listed above are the dates that should be used as this letter was sent after the bulletins, thus Chevrolet would have known EXACTLY when the changeover happened after it had occurred.

[watk69]

what I'd like to know is the last date Chambered exhaust could be ordered as an OPTION. I have been told that date was May 19th no more chambered exhausts could be ordered--- period. If so my 5A Norwood car is getting them. I don't have resonators and would rather not put them on. I like noise

[William]

It's not when it was ordered that matters it is when the car was built. Chambered could have been ordered as late as May. The letter, effective May 19, states "...all orders specifying this option [NC8] will be produced with regular dual exhausts."

The last cars built with NC8 as an option were likely in the N645xxx-N646xxx range, last date of production May 16, 1969. The last 05A cars are in the low N644xxx range so chambered was possible.

The May 19 date is mentioned twice in the letter as it was the date chrome tailpipes became standard with dual exhausts. So the weekend prior, all the now-obsolete parts were likely removed from the assembly plants. Chrome tailpipes included a cost increase and that had to be coordinated with production.

[Stefano]

It is my belief, that maybe a few more Chambered exhaust cars snuck out the door after the above drop dead dates.