N11 Off Road Muffler Stamping Location

[Scott S.]

Re: N11 Off Road Muffler Stamping Location

It looks like there were two different stencils used. Going by Alan's photo of a '65 in post 4, it was two lines of text:

OFF ROAD
......ASSY


Going by Gary's photo of a '67 in post 11, it was all on one line:

OFF ROAD ASSY

I thought maybe it was like Alan's for earlier midyears, and like Gary's for later, but there is another photo of an original N11 exhaust (documented on the tank sticker) of a '67 L71 over on the CF (link: post 23) with the same two-line stencil as the '65 in post #4 above.

[James W.]

Re: N11 Off Road Muffler Stamping Location

Pete Lindahl sent me photos of an NOS N11 exhaust system that has the de-bossed Arvin/Walker part numbers on the mufflers and the off-road stencil is of the two line style. Not sure what year the system was for.

I'm wanting to get this wrapped up over the weekend but still not sure which is correct. Since the 1965 TGJM says nothing about the N11 wording on the mufflers I would think that either would be acceptable???

Anyone concur with this decision?


Regards,

James West

[Jeff C.]

Re: N11 Off Road Muffler Stamping Location

James - did anyone provide you with a source on the stencil? I would be interested in purchasing for my '67... Appreciate any help. jeff Cornwell

[Scott S.]

Re: N11 Off Road Muffler Stamping Location

Pete Lindahl sent me photos of an NOS N11 exhaust system that has the de-bossed Arvin/Walker part numbers on the mufflers and the off-road stencil is of the two line style. Not sure what year the system was for.

I'm wanting to get this wrapped up over the weekend but still not sure which is correct. Since the 1965 TGJM says nothing about the N11 wording on the mufflers I would think that either would be acceptable???

Anyone concur with this decision?


Regards,

James West

James,

I concur that the '65JG doesn't say anything about the N11 wording, but as to whether different styles of wording would be acceptable to any given judge on any given day, there's no way to know. The most recently published midyear JG is the one for 1966. The N11 section says (in part) "The mufflers have a part number embossed on them. The left is 3845735 and the right is 3845736. Original cars have been observed with an 'off-road assembly' paint stamping." (p. 178-179)

So it appears that the 66JG is incorrect on this point (Service parts have the p/n embossed, not production parts), and it looks like they didn't want to be definitive and therefore took an intentional "pass" at the wording, by not even capitalizing the first letter of each word, much less all of the letters.

From the limited photo samples referenced in this Thread, it looks like the two-line stencil was used in 1965 and 1967. So far we only have a photo of the one-line stencil on a '67, not on a '65, so if I had to choose one or the other for a '65 Corvette based on this limited information, I'd go with the two-line stencil.

Does Pete's photo show "OFF - ROAD" over "ASSY", or does it have "OFF - ROAD" over the whole word "ASSEMBLY"? If it says "ASSEMBLY", then we now have three possible variations. As for the stencil, I have not found one yet at any of the usual vendors, so it may be a case where you have to make your own, in which case we need to know the height and width of the letters.

[Gary S.]

Re: N11 Off Road Muffler Stamping Location

To add to the confusion.....here are pictures I found in my files of a 66 bowtie car. I also have pictures of another 67 bowtie car with it's original N11 on but can't see the yellow stenciling because it is blacked out on the bottom on both mufflers...or if I had a closeup picture, maybe it would show through.

Long Island and Corvette Central each have an N11 off road stamp kit for about $20. Others probably have too.

66 Bowtie original N11
66BowtieN11Muffler.jpg

[Gary S.]

N11 Off Road StencilByCorvetteCentral.jpg
The N-11 option was not available in 1963, but we have elected to offer them without the stencil. They look and fit the same as the low performance mufflers, but the difference is in the sound and performance. There are some numbers and prints out there that may lead you to believe that a clamp on version of the off-road muffler was offered. A clamp on style is a great way to go when it is time for new mufflers. They maintain the stock appearance, produce the original sound and feature improved performance.

It appears the only year that the N-11 option was offered for the C3 generation was 1968. The original numbers were 3623603 and 3923604. The parts book shows the numbers 3931803 and 3931804, but seems to indicate that they are a clamp on type. The prints show them with dual mounting brackets, which mean they were useable on 1963-1972. The 1972 parts book has part # 3943385 and 3943386 listed as "off-road", but it does not include the pipes. Prints also indicate that this particular muffler was a dual bracket.

We will be offering a 1968 off-road welded pipe and muffler assembly which can be used on 1970-1972 cars."


Note: The N11 option is listed in the 1963 options listing, but there is no number for how many were installed. It appears CC thinks there were none. Any comments?

[Scott S.]

Re: N11 Off Road Muffler Stamping Location

To add to the confusion.....here are pictures I found in my files of a 66 bowtie car. I also have pictures of another 67 bowtie car with it's original N11 on but can't see the yellow stenciling because it is blacked out on the bottom on both mufflers...or if I had a closeup picture, maybe it would show through.

Long Island and Corvette Central each have an N11 off road stamp kit for about $20. Others probably have too.

66 Bowtie original N11
[ATTACH=CONFIG]42395[/ATTACH]

Gary,

That looks like the same car as shown in post #4 above.

Thank you for pointing out the stamp is available at LIC. I searched there before, but couldn't find it. I searched under the terms "decals", "stencils", "Off-Road", "N11" and others, but you will only find it if you specifically type "off road" without a hyphen. Nothing tricky about that search engine

The LIC product is an ink-stamp, not a stencil. It is modeled after the photo in Adams, p. 366, which it references by page number. That photo shows the whole word "ASSEMBLY" under "OFF ROAD", along with "GM" and the part number embossed in the muffler, so it is a photo of a Service muffler, not a production muffler — which means their ink-stamp may be representative of a production-line stencil/stamp... or it may not.

[Gary S.]

Re: N11 Off Road Muffler Stamping Location

[QUOTE=Scott Smith (50839);634785]Gary,

That looks like the same car as shown in post #4 above.

Ha....that is what happens when these posts drag out over days and you don't go back and review everyone before making your own response. You are right, except in my file I have it labeled as a 66. Maybe the owner will recognize his car and respond!

[Scott S.]

Re: N11 Off Road Muffler Stamping Location

I found the rubber-stamp at CC, it's p/n 322020 and the LIC product is #02-15E. Both are rubber ink-stamps, both appear to be modeled after the Service N11 muffler photo in Adams p. 366. Both are formatted the same:

OFF ROAD
ASSEMBLY

Curiously, Corvette Central gives the explanation and shows the stenciling that Gary posted above (post 21), but their ink-stamp looks nothing like it.


At least a few questions come to mind:

1. Are original production N11 mufflers ink-stamped or painted yellow with a stencil? Photos of originals look like stencils, with stencil-type gaps at the top and bottom of each letter. The reproduction ink-stamps (and the Service muffler shown on Adams p. 366) do not exhibit these stencil-type gaps.

2. Do any original production N11 mufflers use the complete word "ASSEMBLY", or did production examples use only the abbreviation "ASSY" as all of the examples of originals referenced in this Thread?

3. Is there a hyphen between "OFF" and "ROAD" (like the photo in post #3) on any original production OR Service replacement N11 mufflers?

4. Are the letters (whether painted with a stencil or ink-stamped) the same size in the two-line text style and the one-line text style, or does one style use larger text than the other? It appears that the one-line text examples use smaller lettering.

[James W.]

Re: N11 Off Road Muffler Stamping Location

James,

I concur that the '65JG doesn't say anything about the N11 wording, but as to whether different styles of wording would be acceptable to any given judge on any given day, there's no way to know. The most recently published midyear JG is the one for 1966. The N11 section says (in part) "The mufflers have a part number embossed on them. The left is 3845735 and the right is 3845736. Original cars have been observed with an 'off-road assembly' paint stamping." (p. 178-179)

So it appears that the 66JG is incorrect on this point (Service parts have the p/n embossed, not production parts), and it looks like they didn't want to be definitive and therefore took an intentional "pass" at the wording, by not even capitalizing the first letter of each word, much less all of the letters.

From the limited photo samples referenced in this Thread, it looks like the two-line stencil was used in 1965 and 1967. So far we only have a photo of the one-line stencil on a '67, not on a '65, so if I had to choose one or the other for a '65 Corvette based on this limited information, I'd go with the two-line stencil.

Does Pete's photo show "OFF - ROAD" over "ASSY", or does it have "OFF - ROAD" over the whole word "ASSEMBLY"? If it says "ASSEMBLY", then we now have three possible variations. As for the stencil, I have not found one yet at any of the usual vendors, so it may be a case where you have to make your own, in which case we need to know the height and width of the letters.

Scott,

Attached are the pictures that Pete was kind enough to send me.


Regards,

James West
Omaha, NE.

IMG_0917.jpgIMG_0920.jpgIMG_0922.jpg

[Scott S.]

Re: N11 Off Road Muffler Stamping Location

Scott,

Attached are the pictures that Pete was kind enough to send me.


Regards,

James West
Omaha, NE.

[ATTACH=CONFIG]46711[/ATTACH][ATTACH=CONFIG]46712[/ATTACH][ATTACH=CONFIG]46713[/ATTACH]

James,

Thanks very much for the follow up. In re-reading my earlier post quoting the 66JG, it looks like they covered all the bases by referring to it as a "paint stamping"

I can't tell what it says under "OFF ROAD", in both photos (photos #2 and #3) it looks like too many letters for "ASSY" and not enough letters for "ASSEMBLY". It would be hard to make an ink-stamp run like it appears to do on the "Y" in the last photo though, so it seems to have been painted with a stencil rather than rubber-stamped with ink.

[Kim C.]

Re: N11 Off Road Muffler Stamping Location

regarding ink Stamp - Source for this info from Noland Adams Book,page 366
If you want stencil - we can make a stencil:
I added 2 numbers for a stencil
02-15E1 OFF ROAD ASSEMBLY all on one line
and

02-15E2 (on 2 lines)

OFF ROAD
ASSEMBLY

I have no further info on which was used on when - as you show from your sampling above there were variations.

-Kim / LIC

[James W.]

Re: N11 Off Road Muffler Stamping Location

James,

Thanks very much for the follow up. In re-reading my earlier post quoting the 66JG, it looks like they covered all the bases by referring to it as a "paint stamping"

I can't tell what it says under "OFF ROAD", in both photos (photos #2 and #3) it looks like too many letters for "ASSY" and not enough letters for "ASSEMBLY". It would be hard to make an ink-stamp run like it appears to do on the "Y" in the last photo though, so it seems to have been painted with a stencil rather than rubber-stamped with ink.

Scott and Kim,

I am looking at the pictures (enlarged to 100%) that I posted yesterday of the the GM service replacement N11 exhaust mufflers. To answer your question regarding the actual wording on the mufflers it is as follows:

OFF ROAD
ASSEMBLY

It appears that there is a double space between the words off and road and was in fact applied with a rubber stamp. I'd be more than happy to send Pete Lindahl's pictures to anyone who would like to evaluate the lettering for themselves. I like the stencil idea to mark the mufflers, thanks to LIC for making it happen.

Again a big thanks to Pete Lindahl for furnishing me/us with the pictures!


Best Regards,

James West
Omaha, NE.

[John D.]

Re: N11 Off Road Muffler Stamping Location

More worrisome than the lack of the off road assembly stamp specification on the C2 era drawing is the one specifying "embossed asbestos sheet"....

[David K.]

Re: N11 Off Road Muffler Stamping Location

Hi John; David Kalaydjian here in Montreal. I recently bought my 65' 365hp car, and was surprised and happy to find service replacement N11 mufflers from GM, on the car. I bought the stamp kit from Long Island Corvette & will be applying the stamp with supplied white ink today, right aft of the GM part number, which is embossed on each muffler. Great sound from these N11's with the mechanical lifter engine !!!!