Replacement of side exhaust. Carbon steel vs. Stainless steel vs. Aluminized

[Wayne L.]

My '66's original and rusted out carbon steel side exhaust needs to be replaced. I'm having the car Flight Judged in June. What experience do any of you have with points deductions for Stainless Steel vs. Carbon Steel exhaust pipes? For the price difference I think I would prefer to replace the exhaust with a stainless steel product and not have any concerns with future rusting issues. Would I receive a total points deduction for using stainless steel instead of carbon steel? What about the aluminized products, do they receive a full point deduction?

Also can anyone tell me if there is a significant difference is sound between the carbon steel and the stainless steel pipes?

Thanks,

Wayne

[David H.]

Re: Replacement of side exhaust. Carbon steel vs. Stainless steel vs. Aluminized

My '66's original and rusted out carbon steel side exhaust ...

Wayne,

Welcome to NCRS' Tech Board!

Most all judged components are evaluated for both Originality and Condition.

Couple of things.

First: Originality of Exhaust is judged by C.D.C.I.F. guidelines. C Configuration, D Date, C Completeness, I Installation, and F Finish.

Those criteria are to be found in your 1966 TIMJG (Technical Information and Judging Guide). TIMJG tells you WHAT to judge.

If your exhaust is indeed original (i.e. meets CDCIF criteria), then it would receive NO Deduction for Originality.

Originality is judged without regard to Condition.

Condition is judged without regard to Originality (as long as 10% Originality remains).

So, as to your June Flight judging: If Original, then any deductions would be for Condition. Condition judging deductions range from 0 to 75% (as long as the component is still there).

Hence your desire to repair/replace your exhaust has a dilemma: Likely any replacement would generate an Originality deduction. Not doing anything, will generate a Condition Deduction. Up to you to decide which avenue is to your advantage.

Second: In addition to CDCIF deductions for Originality, Standard Deduction Guideline #6 addresses Stainless Steel or Aluminized Replacement Components. There is an ADDITIONAL deduction of 25% for any part that was not originally aluminized, and an ADDITIONAL 50% deduction for any part not originally stainless steel.

This Standard Deduction should factor into any repair/replacement approach. (May just want to take a points hit for longevity)

CDCIF and Standard Deduction Guidelines are found in NCRS' Judging Reference Manual - JRM. JRM tells you HOW to judge.


As to exhaust note, don't have an answer.

Dave

p.s. As your 1966 is recently purchased, I would first check if that side exhaust is indeed original. TIMJG will have "what to look for" items that judges use. I mention this as side exhaust is a very popular feature, and might have been installed years ago. Side exhaust on a car that originally had under-car mufflers generates 100% deductions on exhaust, plus deductions for damage, etc.

Does this car by chance have an A.O. Smith body?

Just make sure before spending.

[Mike T.]

Re: Replacement of side exhaust. Carbon steel vs. Stainless steel vs. Aluminized

Wayne - I understand your concern regarding stainless steel versus the original side pipes made by GM but wanted to add another comment regarding replacement side pipes. I bought a 65 L78 back about 3 years ago. The original engine was MIA but it actually appeared to be one of the original 759 made that year with side pipes. That's the good part, the not-so-good part was that the aftermarket pipes on there at the time, while looking almost brand new, did not sound at all like the exhaust the car came with from the factory. I have three other midyears and all have side pipes. Those other three Corvettes had the side pipes added but...all are running GM pipes, not aftermarket. This 65 396 Roadster I picked up had what we believe were pipes made by a company no longer in business called Sweet Thunder. The baffling inside the pipes were quite a bit different from the stock GM versions and it sounded god-awful. I looked around to see if anyone made a stock or original sound side exhaust for a midyear and at the time, maybe a couple years back, found Allens and Gardners. Allens went out of business around that time so I checked on Gardners. Their website has a section where you can hear their customers cars, some with stock mufflers, some with off-road versions, some with Side Pipes. Of course, hearing a reproduced sound isn't like standing alongside the car so I contacted them and asked if they could put me in touch with some of their customers and they did. Had a good conversation with two customers, both with 67 L71 and they were pleased with their Gardner pipes so I bought a set. The interior baffling (perforated tubes, really) appear to match what GM used back then.
Haven't gotten the new Bigblock fired up yet but hope to soon so I can't report on what they sound like yet.

[Wayne L.]

Re: Replacement of side exhaust. Carbon steel vs. Stainless steel vs. Aluminized

Dave; Thanks for the thoughtful response. I think based on the info you provided I will leave the current exhaust in place until after its Flight judged in June. It will be the first time the car has ever been judged and as a new NCRS member it will be my first time experiencing the judging process. The car has a St. Louis built body and it shows all of the signs of being a real factory equipped side pipe car, and none of the signs of ever having an under the car exhaust system. Yesterday I pulled one of the side exhaust covers off and confirmed that there is absolutely no sign of the metal tabs used to support the rocker panel on non-side exhaust cars ever having been installed or cut off. I'm excited to learn from the Flight Judging process just how "Legitimate" the car is and then deciding from there if I want to improve the car to achieve the next level.

[Wayne L.]

Re: Replacement of side exhaust. Carbon steel vs. Stainless steel vs. Aluminized

Mike; Thanks for the comments on various side pipe suppliers. I will be leaving the existing side pipes on the car until after Flight Judging. Right now I'm leaning towards eventually replacing the pipes with the most accurate carbon steel parts I can find. I had been looking at the typical suppliers i.e. Corvette Central, Paragon, Ecklers, etc. and was not aware of Gardner. I will definitely check them out when the time comes to buy replacement exhaust parts.

[Mark S.]

Re: Replacement of side exhaust. Carbon steel vs. Stainless steel vs. Aluminized

Wayne:

Best of luck on the judging process! I am glad to see that you are getting deeper into the Corvette hobby!

Mark Swanson

[Thomas S.]

Re: Replacement of side exhaust. Carbon steel vs. Stainless steel vs. Aluminized

Wayne - I understand your concern regarding stainless steel versus the original side pipes made by GM but wanted to add another comment regarding replacement side pipes. I bought a 65 L78 back about 3 years ago. The original engine was MIA but it actually appeared to be one of the original 759 made that year with side pipes. That's the good part, the not-so-good part was that the aftermarket pipes on there at the time, while looking almost brand new, did not sound at all like the exhaust the car came with from the factory. I have three other midyears and all have side pipes. Those other three Corvettes had the side pipes added but...all are running GM pipes, not aftermarket. This 65 396 Roadster I picked up had what we believe were pipes made by a company no longer in business called Sweet Thunder. The baffling inside the pipes were quite a bit different from the stock GM versions and it sounded god-awful. I looked around to see if anyone made a stock or original sound side exhaust for a midyear and at the time, maybe a couple years back, found Allens and Gardners. Allens went out of business around that time so I checked on Gardners. Their website has a section where you can hear their customers cars, some with stock mufflers, some with off-road versions, some with Side Pipes. Of course, hearing a reproduced sound isn't like standing alongside the car so I contacted them and asked if they could put me in touch with some of their customers and they did. Had a good conversation with two customers, both with 67 L71 and they were pleased with their Gardner pipes so I bought a set. The interior baffling (perforated tubes, really) appear to match what GM used back then.
Haven't gotten the new Bigblock fired up yet but hope to soon so I can't report on what they sound like yet.

How did it sound on the Big Bloc?

I had to replace the driver side because the inside baffle came loose. I do have a real side pipe 67, but I doubt they were original. In any event, I decided to replace defective one 1st and honestly not at all happy with the sound, compared to the driver side. To be precise, the driver side has the deep sound you would expect (rumble) but the Gardner side has more of a clacking sound. The heat riser is tied off so it's not noise.

the difference is more pronounced when you get on it. Hoping it's a "break in" thing but honestly not because it's been several hundred miles like that.

appreciate your feed-back.

[John F.]

Re: Replacement of side exhaust. Carbon steel vs. Stainless steel vs. Aluminized

I know this an old post, but how did the judging go?

[Wayne L.]

[Wayne L.]