Off Road Exhaust

[John H.]

Re: Off Road Exhaust

Does anyone know how many baffles the original Off Roads had and who made them?

Greg -

The midyear N-11 mufflers were manufactured by Arvin, not Walker; Walker only made the standard production mufflers, which have the "W" embossment. The Arvin-manufactured N-11 mufflers don't have the "W" - just the yellow stencil.

[Greg D.]

Re: Off Road Exhaust

Thank you

[David S.]

Re: Off Road Exhaust



-Dave

[Ralph A.]

Re: Off Road Exhaust

-Dave
Dave are your n11 mufflers aluminized or galvanized thanks Ralph

David are your n11 mufflers aluminized or galvanized thanks Ralph

[John H.]

Re: Off Road Exhaust

David are your n11 mufflers aluminized or galvanized thanks Ralph

Ralph -

Original muffler shells (standard and N-11) had an aluminized outer wrap; the end caps were stainless on the RH muffler, and aluminized on the LH muffler. Pipes were plain steel.

[Wayne M.]

Re: Off Road Exhaust

.....Original muffler shells (standard and N-11) had an aluminized outer wrap; the end caps were stainless on the RH muffler, and aluminized on the LH muffler. Pipes were plain steel.

John -- would this stainless cap apply to GM service as well ? I just checked my GM N11's (circa 1982) with a magnet and cannot detect any difference in "pull" on either the fore and aft caps of the LH and RH mufflers. Of course there are many "stainless" formulations, with various magnetic properties from strong to non-existent. But I do notice that the rear rim of the cap on the RH is surprisingly shiny.

Did this have something to do with corrosive combustion condensation due to the heat riser valve ?

[Ralph A.]

Re: Off Road Exhaust

Ralph -

Original muffler shells (standard and N-11) had an aluminized outer wrap; the end caps were stainless on the RH muffler, and aluminized on the LH muffler. Pipes were plain steel.

Hi john the judging manual states that The external muffler has a galvanized steel coating. I always thought their was a difference between something being galvanized and aluminized, am I wrong thanks Ralph

[John H.]

Re: Off Road Exhaust

John -- would this stainless cap apply to GM service as well ? I just checked my GM N11's (circa 1982) with a magnet and cannot detect any difference in "pull" on either the fore and aft caps of the LH and RH mufflers. Of course there are many "stainless" formulations, with various magnetic properties from strong to non-existent. But I do notice that the rear rim of the cap on the RH is surprisingly shiny.

Did this have something to do with corrosive combustion condensation due to the heat riser valve ?

Wayne -

I'm sure it was related to the heat riser operation, as even with the premium material, the RH side muffler was always the first one that rusted out; that muffler never reached the same temperature as the LH muffler.

[John H.]

Re: Off Road Exhaust

Hi john the judging manual states that The external muffler has a galvanized steel coating. I always thought their was a difference between something being galvanized and aluminized, am I wrong thanks Ralph

Ralph -

The judging guide is in error; Chevrolet Engineering says the outer wrap of both original mufflers was aluminized steel. Later service replacements may have been different.

[Joe L.]

Re: Off Road Exhaust

Ralph -

The judging guide is in error; Chevrolet Engineering says the outer wrap of both original mufflers was aluminized steel. Later service replacements may have been different.

John, et al------


The GM SERVICE mufflers, both N-11 as well as standard, used an aluminized outer wrap right through the end of their manufacture. However, some Walker and Arvin premium-line SERVICE mufflers available LONG AGO were internally and externally identical to the GM mufflers EXCEPT that the outer wrap was galvanized. Why Walker and Arvin, who also manufactured the GM PRODUCTION and SERVICE mufflers, used galvanized wrap on their mufflers is unknown to me.

The aluminized coating is obviously a fused ALUMINUM material. Galvanized is an electro-deposited or hot-dipped ZINC coating.

[Terry M.]

Re: Off Road Exhaust

I remember reading someplace, and I think it was the AMA Specifications for early C3s, that the outer wrap of the muffler was galvanized. I can tell you from my originals that under that is a sheet of gray fiber material. I would give you my best guess as to that material, but I think you can figure out that part.