Chambered Exhaust

[uscrichter]

Thanks Guy's! I am a purist , however this one I have had since a my high school Sr. year and always wanted to put the NOS crossram on it which of course takes it out of contention for originality along with the other GM over the counter parts i.e.;  transistor ignition, fiberglass hood, headers, etc.. but still want as much originality without sacrificing performance and safety, Then there are those parts that went missing like the oil sending line which I have just seen sell on eBay for $190.00! vs. $14.00 for a repop , that no one would notice unless being concourse judged, hard for me to justify! from a performance standpoint it doesn't sound like the original configuration would make much of a difference to warrant not using the resonators.

[crossboss]

This old thread mentions a horse power decrease with the chambered exhaust system between 7-15 HP, does anyone know if the later style exhaust with resonators vs. the earlier style without resonators have a difference in HP? I am ordering parts for my late August '69 Z which would have had resonators and would like to maximize the engine output since I don't plan on having my car judged for total originality I am wondering which system would maximize the HP output.   

John Z told me once that the chambered exhaust cost 7 hp over the non-resonator single muffler (dual in dual out) system.   I'm sure the resonator is more 'lossy' than without the resonators.

That said, I'm in the same boat as you.. mid Sept '69 car, so my will get the resonators when I get it back together.

A 7HP loss wont even be noticeable in my opinion.

[x66 714]

The chambered exhaust was discontinued before your car was even ordered. The nice thing about your car, like mine, is they came with chrome tail pipes. Whatever you do, I would leave that feature. Both my cars came without resonators & the sound sweet. I'm a purist & i would put it back to how it left the factory..Joe

[uscrichter]

Joe, If one of your cars is close to the production date of my car wouldn't it have come with the resonators and the chrome exhaust tips? I know mine came with the exhaust tips, but replaced my exhaust system with glass packs in the early eighties and cannot remember  which exhaust system was on the car  and according to the info. here it should have the resonators unless I,m missing something? and do agree that the slight amount of performance isn't worth not keeping it stock. Curt

[x66 714]

Curt. It doesn't appear the big block cars followed that practice of resornators. I still have my original system on the car. I know of a May 375hp car that's the same as mine..Joe

[firstgenaddict]

Regarding chrome exhaust pipes -
The exhaust pipes on Dave Beems 05A L78 conv N643495 were not chrome - the ones on his 05D L78 conv  N648797 are chrome - do we know the the exact change over range? 

Joe - When did 68 Z28's get resonators? I had an original day two take off 68 Z exhaust system which had resonators, I know the car was BRG so I assume it was built in the 2nd half of production - Jan-July 

[william]

The changeover date for chrome tail pipes was May 19.

ZL1 #3 was built with resonators [production N10 system] per the recall.

[x66 714]

James. I didn't realize 1968 Z/28s had resonators. That contradicts what Jerry MacNeish says in his books. He says the 67/68 Z/28 never had resonators, only the ss350 & 325hp 396. I thought that was a 1969 thing. Thanks for the information. Something I will need to consider once I get all the pieces to put it back to factory. Thank you, Joe

[firstgenaddict]

I don't know what to say about ALL 68 Z's not having resonators. The system I had was definitely off a 68 Z - my dad was really good friends with the owner Ossie Delaney, (whom I met many times and would still talk about street racing his 68 Z into the 1980's) who bought the car new in Greenville SC, immediately took it to Nalley Chev in ATL and had the engine gone through heads ported, off road cam installed, rotating assembly balanced, & then everything equalized - blue printed, 4.88's installed, along with 67 vette side pipes - he worked for my grandfather from 66-75 and along side my father 71-75 which is how my dad and then I came about the system.
When I sold my 68 RS SS 396 project in the early 1990's the system was stacked in the car -  Tinkerr a member and participant in discussions here - bought the car from me, however he moved in the mean time and cannot find the system.


William - I thought that some of the BB's got the resonators but not 100% - I remembered the photo you posted - one thing about that photo - the pipes coming into the resonators look HUGE.

[x66 714]

There's lots we don't know & may never know....Joe

[william]

Yes, there have been a few original exhaust cars over the years w/o them. They are an exception; there is no mention of that in service docs or the AIM. NF2 is in the '68 AIM, not '69.

Some did, some didn't.

[firstgenaddict]

NF2 was with resonators?

[x66 714]

NF2 was with resonators?

NF2 was without resonators & was the standard feature of 1968 Z/28s. N10 was with resonators & was standard on SS models. I wonder if the Z/28 that system came off of was ordered with the N10 option but I really don't see on the option sheet how to do that...Joe

[firstgenaddict]

I always thought it was odd because I was like why two mufflers? and one directly under the rear seat floor pans, but I understand now they are resonators.
The car was special ordered by Ossie, If not mistaken it was a cowl plenum 4.10 with Hounds tooth car -his father owned the first, at that time only Mercury Marine dealership in Greenville.
Man a BRG 68 RS Z would look wicked with 67 vette side pipes and cragar big and littles gabriel hi jackers in the back.