NC8 - Chambered Exhaust

[YENKO DEUCE REGISTRY]

When did the NC8 option get cancelled? I thought it was 12/68, but I have a copy of an invoice for a '69 Chevelle dated 7/69 that has the following; L78, M21, G80, F40, 001 - special paint, and NC8 chambered exhaust system, plus a host of other options. Interesting invoice.
M

[L72COPO]

Marlin, I have always been under the impression that chambered exhaust was standard on certain cars (Z-28 and 375 HP) until cancelled in December due to noise complaints from owners (read tickets). However it remained an option that could be ordered.
Yesterday I talked with a gentelman that ordered a 375HP Chevelle and took delivery in Sept. 69, it have chambered exhaust and he definatley did not order it.

[Mr70]

I have a Chevrolet Technical Service Bulletin #69-T-8 issued Dec.1968.
It states that on November 25 1968 the NC8 Chambered Exhaust system was no longer Standard equipment on Camaro SS & Z-28 and Chevelle SS,but was now optional,due to the excessive noise levels deemed by some local police depts.
It goes on to say the RPO NC8 will still be available as optional equipmentin those areas where the system is permissible.
So I believe this to mean it was possible to get it optionally,depending on where in the country you lived.
But when I open up my 1970 Assembly Manual,it says that RPO#NC8 is cancelled for good for the Chevelle as of May 19, 1969.
This adds confusion as to why the 2 later Chevelles stated early recieved it so late in production.

[YENKO DEUCE REGISTRY]

Thanks for the info! I thought that the option was completely cancelled in 12/68, but now I see that it just became an option.

I'm trying to do some digging on this '69 Chevelle, only because it has some neat options - like special paint.
Thanks,
M

[JoeC]

I have seen the NC8 on more then one build sheet on Chevelles built in June/July.

[Keith Tedford]

I also have GM of Canada info on a June or July COPO Chevelle with the NC8 chambered exhaust.

[Alan Colvin]

Would anyone be interested in purchasing the same stainless chambered exhaust that was produced back in 1985-86 under the C & C Automotive business name? I still have the original tooling and fixtures and would consider producing it again if the demand is there. Maybe some of you guys still have the systems I sold you back then from the late 1980's. Let me know..

Alan Colvin
Chevrolet by the Numbers
[email protected]

[Alan Colvin]

All my original systems are easily ID'd, as all of them have a small C inside of a C logo stamping (C & C Automotive) on each component of the system. The stampings were usually at the end of each pipe. The hangers were also stamped with the logo as well.

[Alan Colvin]

Oh yeah..they were manufactureed from 409 stanless with a 304 internal tube. The hangers were also zinc plated and used original spiral rivets.

[Unreal]

thanks,
Now that you say it, I think they did say 409. I'll look for the mfg stamp.

[Unreal]

Alan,
I think I got one of your systems from D&R in Chicago. Was it 410 stainless, and supposedly made from the original tooling?
I'm happy with the system, just trying to confirm the story I was told.

[Jeff H]

Hey alan, is that chambered system 2", 2-1/4" or 2-1/2"? I want to put the chambered system on my JL8 crossram car when it's finished but I'll be running headers and would prefer 2-1/2" tubing to help it breath. I realize it won't be 100% stock original, but it will look period correct.

Jeff H. - 69 Z28 JL8, crossram and GM fiberglass hood, TI, radio delete, heater delete, 93 Z28 Indy 500 Pace Car - supercharged and for sale!

[Chevy454]

Well, I think the original were 2" (I think), so that is probably what Alan's are also. The chamber diameters are 3", but the inlet/outlets are only 2" (again, I think that's what they are...I am too lazy to measure ours and see!). The worst part is where it flattens under the cross member and right before and right after the last chambers.

I am kind of undecided if we should keep our chambered, or get the "correct" dual into transverse muffler type exhuast. I'm not sure which one would yeild better performance http://www.yenko.net/ubb/smilies/images/icons/crazy.gif.

[Jeff H]

I know that there is one place making a 2-1/4" chambered system but I'd like to get a 2-1/2". I have plenty of time until my car gets to that point. I thought I remember reading that the stock chambered system cost the ZL1 80 hp.

[Chris396]

I had the transverse muffler type system with the resonator on my car before I switched to the chambered. I didn't notice any difference between the two other than the noise http://www.yenko.net/ubb/smilies/images/icons/smile.gif

[Belair62]

I actually though I picked up a bit of power...at least it SOUNDS faster !!!!

[YENKO DEUCE REGISTRY]

Chris396;
Before you installed the chambered system, did you happen to try removing the over the axle pipes, tranverse and tailpipes and just running through the resonators?? I am considering doing this with my car to see if it wakes it up any. I don't think my car car would make it into the 13's right now, but I have to learn how to tune it correctly. Last night I barely got a chirp out of second gear, and I had it floored shifting at 5500 rpm!! Timing, jetting and valve lash?? It was a very depressing drive, my only consolation was that Pete's COPO and Neal's Yenko Nova's have run mid 13's - that's my goal.
M

[Edited by YENKO DEUCE REGISTRY (10-19-2001 at 08:10 AM).]

[Chris396]

No Marlin I didn't but that is a good idea.

[Chevy454]

OK, I got to looking at my notes inquiring about the chambered vs. transverse exhuast systems, and it looks like the in/out diameter of the chambered is 2". So, if Alan's exhuast is copied after the originals, it should probably be 2" as well.

Now, you mentioned looking for a 2.5" chambered system. The only chambered exhuast that I know of that big in/out is for the late model '93-'99 F-bodys, offered by Braxton (http://www.firstgen.com/Braxxton.htm) .

The biggest problems with the original type exhuast is the usual bends and crimps in the head pipes and tail pipes, in both systems. So, I'm not sure how much difference their would be performance-wise between the two. Now, if you could swap out the crimped head/tail pipes with something with a mandrel bend in it, then that should yield a gain.

[JoeC]

I see some guys using an "X" pipe instead of a cross over pipe. It is supposed to have better scavenging effect and a little more HP then crossover pipe.

[Chevy454]

Check out these 2 articles (they are the same test, just different charts):

http://www.wauknet.com/douthitt/exhaust.htm

http://www.atlantabuick.com/Mufflers.htm

See, the proof is in the pudding! Er, uh, I mean ETs http://www.yenko.net/ubb/smilies/images/icons/wink.gif!

[NOTE: those links appear to be dead, so I am digging through my "favorites" trying to find some good links. Sit tight.]


[Edited by Chevy454 (10-19-2001 at 11:45 AM).]

A buddy of mine has a '70 LS6 Chevelle, that is an original car, but is not a numbers matching car. He had put a set of repro chambered pipes on the car, because he liked the sound. Another friend has the same car, but with 2 chamber Flowmasters, and his car was 3 tenths faster. I would go with a nice set of Flowmasters with and a cross over pipe if I was looking at 1/4 times. IMHO.

[Chevy454]

Greg:

Those 2 comparisons don't surprise me. If you look at the original chambered exhuast (or even the original dual exhuast) from a performance stand point, it will make you sick. But, I am a true blue purist, and I would like to keep our Camaro as stock as possible. BUT, now that I'm in the 12s on the stock exhaust...a few tenths would be nice... http://www.yenko.net/ubb/smilies/images/icons/wink.gif!