N11 Off Road Muffler Stamping Location

[James W.]

I've searched this topic on the TDB and found a few threads that reference the N11 off-road mufflers with some pictures specific to a 1967 Corvette. I am looking for information on the location of the N11 off-road assembly stencil or stamping specific to a 1965 Corvette if there is a difference based on how the muffler was blacked out. What I've seen in the pictures is that the stamping is relatively centered on the road side of the muffler and runs parallel to the long axis of the muffler.

Was the stamp applied so that the words "Off-Road Assembly" can be read from back to front on the passenger's side muffler and from front to back on the driver's side muffler? I'm getting ready to apply these marking on my '65 mufflers.

Thanks,

James West
Omaha, NE.

[Michael H.]

Re: N11 Off Road Muffler Stamping Location

I've searched this topic on the TDB and found a few threads that reference the N11 off-road mufflers with some pictures specific to a 1967 Corvette. I am looking for information on the location of the N11 off-road assembly stencil or stamping specific to a 1965 Corvette if there is a difference based on how the muffler was blacked out. What I've seen in the pictures is that the stamping is relatively centered on the road side of the muffler and runs parallel to the long axis of the muffler.

Was the stamp applied so that the words "Off-Road Assembly" can be read from back to front on the passenger's side muffler and from front to back on the driver's side muffler? I'm getting ready to apply these marking on my '65 mufflers.

Thanks,

James West
Omaha, NE.

James,

I'm not sure about this but I don't think assembly line off road mufflers had a stencil of any kind.

I know that those sold in service in the very early 70's didn't have it but those sold starting at some time in the mid to late 70's did.

Either way, if it was included on the outer side of an assembly line muffler, it would have been covered during the blackout process.

[Mike E.]

Re: N11 Off Road Muffler Stamping Location

I don't know that these are correct...Perhaps someone else could say...They were on a '65 at Bloomington this summer.

[Alan D.]

Re: N11 Off Road Muffler Stamping Location

And another 65 which purports to be original.
The later service replacements seem to have embossed numbers (purchase around 1972, do have receipt) as shown in second picture.

[James W.]

Re: N11 Off Road Muffler Stamping Location

Mike,

Thanks for the pictures. Those paint runs sure do look a lot like they were applied with a black magic marker?! I've been told that the tops only of the 1965 mufflers were blacked out so that's what has been done to mine against my better judgment since the judges are now starting to look for the muffler black out. Personally I think it makes no sense that GM would black out the top surfaces only and I think it looks like hell. I'm actually thinking about taking some lacquer thinner on a rag and removing it. I definitely will after the car goes through judging.

Regards,

James West

[John H.]

Re: N11 Off Road Muffler Stamping Location

I don't know for sure, but I'm thinking that the stencil may have been on the production-line N-11 muffler assemblies, if for no other reason than it was the only way for the assemblers in the plant to tell the difference between the "regular" pipe/muffler assembly and the N-11 pipe/muffler assembly; they were otherwise identical externally. Not an issue with Service parts, as the N-11 muffler was the only one that was furnished as a welded assembly with the intermediate pipe; the regular Service replacement mufflers only came with the bent inlet pipe that was to be clamped to the cut-off end of the original intermediate pipe.

The embossed coding on the Service N-11 in the second photo indicates that it was made in November of 1970; according to the drawing, the original production-line N-11 mufflers had no embossed date coding.

[John D.]

Re: N11 Off Road Muffler Stamping Location

Noland's book has a pic of an N11 muffler in the 1966 section that has the off road stencil...

[Michael H.]

Re: N11 Off Road Muffler Stamping Location

I think it would be unusual for GM, or one of the vendors that supply parts to GM to use a stencil to ID a part that was to be used on the assembly line. I would think any ID would be in the form of a color paint stripe, or at most, the option code N11.

I can't think of any other assembly line part from that era that had anything similar.

[James W.]

Re: N11 Off Road Muffler Stamping Location

Does anyone have a vendor source that sells the off road assembly stencil, not the stamp kit.


Thanks,

James West

[Peter L.]

Re: N11 Off Road Muffler Stamping Location

James - I expect the stencil might vary but I can agree that color was yellow. The set I have reads as follows in all capital letters on 2 lines:

OFF ROAD
ASSEMBLY

and you have to have some imagination to read all the letters and the application wasn't very neat or pretty.
Pete

[Gary S.]

Re: N11 Off Road Muffler Stamping Location

I think these have been posted before......George Weaver's 67 435 before he bought it and obviously before it was cleaned up. This showed 14K miles and was taken off the road in 1969 as I remember.

Also, specific to 1965, you might want to contact Elmer Schuster in New Mexico. He told me years ago he had an original 65 with its original N11 exhaust system on it. As I remember his description was like this 67....no embossing and the yellow stencil. Not sure about blackout.
OffRoadN11MufflerPixByPageCampbell.jpg

[John D.]

Re: N11 Off Road Muffler Stamping Location

I don't know for sure, but I'm thinking that the stencil may have been on the production-line N-11 muffler assemblies, if for no other reason than it was the only way for the assemblers in the plant to tell the difference between the "regular" pipe/muffler assembly and the N-11 pipe/muffler assembly; they were otherwise identical externally. Not an issue with Service parts, as the N-11 muffler was the only one that was furnished as a welded assembly with the intermediate pipe; the regular Service replacement mufflers only came with the bent inlet pipe that was to be clamped to the cut-off end of the original intermediate pipe.

The embossed coding on the Service N-11 in the second photo indicates that it was made in November of 1970; according to the drawing, the original production-line N-11 mufflers had no embossed date coding.

John

The drawing doesn't seem to call out the "off road assembly" stencil either. Could it have been done in St. Louis or an informal agrrement with the supplier perhaps ?

thanks

john

[John H.]

Re: N11 Off Road Muffler Stamping Location

John

The drawing doesn't seem to call out the "off road assembly" stencil either. Could it have been done in St. Louis or an informal agrrement with the supplier perhaps ?

thanks

john

John -

Most likely it was an agreement of some sort between Engineering, St. Louis, Purchasing, and Arvin to provide the stencil identification at Arvin, and it never got to the stage of requiring an ECR, thus never showed up on the drawing as a change.

[Mike E.]

Re: N11 Off Road Muffler Stamping Location

John -

Most likely it was an agreement of some sort between Engineering, St. Louis, Purchasing, and Arvin to provide the stencil identification at Arvin, and it never got to the stage of requiring an ECR, thus never showed up on the drawing as a change.

Looking at the production numbers, N11's were only installed on 10% or less of cars produced....So this seems like it would be pretty likely.

[Tony S.]

Re: N11 Off Road Muffler Stamping Location

James, I recently posted photos of Dave Sindelar's 9000 original mile 396 car's original exhaust system. The mufflers still have the original black out paint on both mufflers. The black out paint was applied equally on the upper and lower OUTBOARD side of each muffler. There were runs that run inboard on the upper and lower sections. Email me if you'd like for me to send you the photos.

Tony