C2 Stainless Steel Exhaust Tips.. 304ss or 409ss?

[James W.]

Hello,

I recently had my car flight judged at the Heartland Chapter meet back in September. The NOS exhaust tips that I purchased from GM back in 1981 that I installed when I originally restored and are currently on the car were judged as not original and received a points deduction. The reason why they were judged this was because the judge's magnet did not stick to the exhaust tip when applied. Again, these exhaust tips were purchased over the counter from my local GM dealer back in 1981 and carry the correct GM part number and have the correct seam that runs the length of the exhaust tip. After 23 years of service there is no sign of rust anywhere on these tips.

When you think of stainless steel you assume it is usually a 304 or 316 grade, not the magnetic 409 grade. What did GM use from 63 to 67?

Where the exhaust tips judged correcly??? In my opinion they were not. I know that stainless steel exhaust pipes, clamps, heat shields, etc. are a no no in flight judging, but are the exhaust tips supposed to be the opposite, as in a magnet should stick to them when applied?

Just trying to get some clarrification for my own knowledge as a 63/64 judge.

Best Regards,

James West
Omaha, NE.
Member #18369
NCRS Nebraska Chapter Co-Chairman / Judging Chairman

[Joe R.]

Re: C2 Stainless Steel Exhaust Tips.. 304ss or 409

James,

I just walked out in the shop and picked up an original exhaust tip. Reached and got a magnet off the tool chest and quess what? The magnet nearly sucked the tip from my hand. This must mean that originals were a poor grade of stainless such as 409 however 409SS will rust and the old original tips still look good with no surface rust.

Based on this I would deduct that the original SS tips were a higher grade than 409SS but not 304SS.

Originals will be attracted by a magnet for sure. I know this does not answer your original question but it does vindicate the judge.

Regards,

JR

[Michael H.]

Re: C2 Stainless Steel Exhaust Tips.. 304ss or 409

Joe,

Isn't there also a difference between original equipment and later replacements with the replacements having the GM part number stamped into them? I know original 63's don't have the part number but I don't know about 64-67.

Michael

[Mike M.]

Re: C2 Stainless Steel Exhaust Tips.. 304ss or 409

mike: my experience with the extensions duplicates your experience. origianls lack part # stamping whereas service replacements will have part # stamped there-on. mike

[Joe R.]

Re: C2 Stainless Steel Exhaust Tips.. 304ss or 409

Mike,

I have several examples of original mid year tips and none have the part number stamped into them. All the replacements have the part number stamped into the tip at the clamp area.

JR

[Eugene B.]

Re: C2 Stainless Steel Exhaust Tips.. 304ss or 409

James et al,
Another data point from my original '65. Exhaust tips are magnetic and have no part number that I can find.

Looks like the deduct was an honest find, but I'll make a comment that I've made before. JG always speaks of "item must appear as original". This is a visual characteristic. I don't support the idea of judges having magnets, frying pan sized magnifing glasses, bore scopes, etc.

Enough from the soap box. Good Corvetting to all.

Best regards,
Gene

[Gary B.]

66 TIM&JG; numbers vs. not; magnetic vs. not

Guys,

About the exhaust tips, the '66 TIM&JG says "Most have visible stamped part numbers." Now I've read the current and past discussions on this topic and some people contend that originals did not have the numbers. Until the JG reflects this opinion I, as a chassis judge, will continue to give full points with or without the numbers, based on the "Most have" wording in the TIM&JG.

On the matter of stainless and magnets, the mistake I've made in the past and the mistake I've seen a number of other judges continue to make, it to take a deduct if a magnet sticks, since this is a classic (but not always correct) test for stainless. Just like some parts of the ignition shielding on mid-years, the tailpipe entensions are made from a martensitic (400 series) grade of stainless and therefore magnetic.

The one thing I have learned is to take a deduct if a magnet does NOT stick to the tailpipe extension, since this indicates that an aftermarket vendor has probably used a grade of stainless, like 304, which is not magentic, thinking that the GM tips were not magnetic, but not having done their homework in order to find out that this is not the case.

The question I still have is, how does one distinguish between a magentic stainless steel and a comparable looked plated non-stainless steel?

Gary

[Michael H.]

Re: C2 Stainless Steel Exhaust Tips.. 304ss or 409

Thanks Mike. I'm going to look at my 66 car to see if they're stamped with the part number but I'm not 100% sure they're the originals. I'll also try to find a magnet. Interesting discussion and I'm learning as we go. Never knew there was a difference in the actual stainless material.

Michael

[Michael H.]

Re: C2 Stainless Steel Exhaust Tips.. 304ss or 409

Joe,

Did the non numbered pipes continue on through the end of 67? Thanks,

Michael

[Pete Van Seggern #30920]

Re: C2 Stainless Steel Exhaust Tips.. 304ss or 409

I bought my '63 in '66 and have to believe that the exhaust system was original. I replaced it with Chevy parts in '67, including new tips. The replacement tips have a full part number on them. I still have one of the originals and it has only an "A" on it.

[Michael H.]

Re: C2 Stainless Steel Exhaust Tips.. 304ss or 409

James,

Between Bob Jorjorian and I, we have tested 22 original tail pipes today and all are magnetic. Most are used, some are with part number and some without. Several new sets but probably none made after about 1980. I suppose it is possible that GM changed vendors or just changed the spec's on the stainless in later years which would account for the non magnetic pipes that some are reporting.

As for the part number stamp,I haven't been able to document any non numbered pipes on any car later than 63 yet but I'm hoping more info will come into this board. It's difficult to say for sure if pipes are the original, even on low mileage cars. Hope someone will add to this.

Michael

[Eugene B.]

Re: C2 Stainless Steel Exhaust Tips.. 304ss or 409

Michael,
Perhaps I am not understanding the second paragraph of your posting. You wrote that "... have't been able to document any non numbered pipes on any car later than 63...

I have carefully looked at my original '65 tips several times for part numbers. I have them in front of me now and I'm convinced that they do not have P/N's.

Regards,
Gene

[Eugene B.]

Re: 66 TIM&JG; numbers vs. not; magnetic vs. not

Gary,
Regarding your question. What would be the difference in appearance between original magnetic stainless and plated non-stainless?

First, one might consider the material thickness. My original '65 tips have a material thickness of .025 inch. I doubt that an after market manufacturer would roll carbon steel tips from .025 material. They would probably not be substantial enough.

Second, one should consider the plated finish. I doubt that original stainless tips would have a "show quality" chrome look (like a bumper). The stainless, although shiny, has a look of its own, if you know what I mean. Plated tips would also look different on the inside diameter surface. Although, presence of exhaust gases and soot might make this difficult to discern.

My thoughts.

Regards,
Gene

[Michael H.]

Re: C2 Stainless Steel Exhaust Tips.. 304ss or 409

Sorry Gene, I do remember reading that in your post but forgot to include it in the results. Probably was too wrapped up in looking through my notes.

I've gotten several emails on this since yesterday and several people with 63 to 65 (mostly 63-64) have said they have the original non numbered pipes from their cars but none from 66-67. Hopefully we'll get more info from owners and they'll post here. Thanks,

Michael

[James W.]

Re: OOPS!!! I Mis-Spoke, Please Read

OOPS? I mis-spoke when I said in my original message that I received a points deduct because the judges magnet would not stick to the exhaust tips I did not get it right. I should have written that the judges magnet DID stick to the exhaust tips and I was told that the originals should not attract a magnet.

So what is correct? Again these tip are NOS/GM service replacments bought back in 1981.

Sorry for the confusion.

Regards,

James West