N11 Muffler Seams Crimped or Welded?

[James W.]

I'm starting a C2 N11 exhaust/muffler thread based on the thread by Kurt Kobusch that was asking about the N11 exhaust system muffler stamp configuration; https://www.forums.ncrs.org/showthre...amp-or-stencil.

In that post, Rocco Scotellaro and Tim Gilmore posted a 1967 original N11 mufflers with the yellow ink stamp. I asked Tim if the muffler seams were crimped or welded. Tim posted another picture which looks to be a crimped joint at the outboard seam. Why I asked is that the current 1965 Judging Guide states that original N11 mufflers have a both the inboard and outboard muffler seams welded as opposed to crimped on the regular exhaust system. I know we are talking about two different model years, I'm just looking for some discussion on this.


Thanks,

James

[Joe L.]

Re: N11 Muffler Seams Crimped or Welded?

I'm starting a C2 N11 exhaust/muffler thread based on the thread by Kurt Kobusch that was asking about the N11 exhaust system muffler stamp configuration; https://www.forums.ncrs.org/showthre...amp-or-stencil.

In that post, Rocco Scotellaro and Tim Gilmore posted a 1967 original N11 mufflers with the yellow ink stamp. I asked Tim if the muffler seams were crimped or welded. Tim posted another picture which looks to be a crimped joint at the outboard seam. Why I asked is that the current 1965 Judging Guide states that original N11 mufflers have a both the inboard and outboard muffler seams welded as opposed to crimped on the regular exhaust system. I know we are talking about two different model years, I'm just looking for some discussion on this.


Thanks,

James

James------


I have never seen any 1963-72 Corvette muffler, N-11 or standard, PRODUCTION or GM SERVICE, with anything but crimped seams. The only welds I've seen relate to the attachment of the front and rear pipe extensions.

I have seen certain "reproduction" mufflers with welded seams, though.

[James W.]

Re: N11 Muffler Seams Crimped or Welded?

Joe,

I find it hard to believe that there would have been a different assembly process by the original vendor for the off-road 2-1/2 inch exhaust system mufflers and the regular 2-1/2 inch system. To me you have the same case and just fewer baffles.

James

James------


I have never seen any 1963-72 Corvette muffler, N-11 or standard, PRODUCTION or GM SERVICE, with anything but crimped seams. The only welds I've seen relate to the attachment of the front and rear pipe extensions.

I have seen certain "reproduction" mufflers with welded seams, though.

[Dorsey F.]

[Harry S.]

Re: N11 Muffler Seams Crimped or Welded?

Here is the replacement 1963 N11 Gardner muffler that will be installed in a few weeks. It passed judging at a National with no deductions.

IMG_4390.jpg

IMG_4391.jpg

IMG_4392.jpg

[James W.]

Re: N11 Muffler Seams Crimped or Welded?

Thanks Harry and everyone who have replied. I'm going to put on the same system on my '65 in the next few weeks.

I'll contact Tony Stein to inquire about why that statement is in the 1965 Judging Guide.

James

[Dave S.]

Re: N11 Muffler Seams Crimped or Welded?

While we are on the N-11 topic if I recall correctly there is a source for the OFF ROAD stencil. Can anyone advise on where to find one.??
Thanks

[James W.]

Re: N11 Muffler Seams Crimped or Welded?

I would try ZIP, part number MF-512 or MF-513, both $14.99 each. You'll have to decide which one in correct based on what your current NCRS Judging Guide says. I bought mine from LIC before they closed. The ones in ZIP's catalog look like the one I purchased.

James

While we are on the N-11 topic if I recall correctly there is a source for the OFF ROAD stencil. Can anyone advise on where to find one.??
Thanks

[Dave S.]

Re: N11 Muffler Seams Crimped or Welded?

I would try ZIP, part number MF-512 or MF-513, both $14.99 each. You'll have to decide which one in correct based on what your current NCRS Judging Guide says. I bought mine from LIC before they closed. The ones in ZIP's catalog look like the one I purchased.

James

Thanks James. Hopefully someone on the JG revision team will jump in. I gave up guessing when it comes to the 1965 details.

[Keith B.]

Re: N11 Muffler Seams Crimped or Welded?

With all respect how can a reproduction muffler have zero deductions when they don't flatten there pipes and the muffler is not properly welded? Even the NOS service replacement N11 mufflers take a hit because of the the addition part numbers. The muffler that Tim Gilmore has on his car is absolutely original.

[Gary B.]

[Harry S.]

Re: N11 Muffler Seams Crimped or Welded?

The muffle I pictured was just out of the box. After installation it was welded, pipes were correct and the blackout was applied as appropriate. Per the judging rules, does it appear original. That was all I was looking to attain.

[Keith B.]

Re: N11 Muffler Seams Crimped or Welded?

With all respect how can a reproduction muffler have zero deductions when they don't flatten there pipes and the muffler is not properly welded? Even the NOS service replacement N11 mufflers take a hit because of the the addition part numbers. The muffler that Tim Gilmore has on his car is absolutely original.

[Keith B.]

Re: N11 Muffler Seams Crimped or Welded?

Do they have the "A" debossed on each side of the muffler as described in the judging manual. I have paid thousands of dollars in the past on NOS pipes and mufflers and have always taken a hit that they were service replacement.

[Ken R.]

Re: N11 Muffler Seams Crimped or Welded?

Back in the day (pre 2000) I bought 2 muffler sets from GM before GM dropped them from the warehouses. One came out of Lansing, the other PA warehouses. Both had square inlet pipes and pipes were welded to the mufflers. Here are a couple of photos. They may be the ones Tim is showing as I sold them to him.IMG_0282.jpgIMG_0283.jpg " A " is stamped on body of both and ends are rolled.