Judging LS4 exhaust

[William M.]

I have a 73 LS4 auto. When it was judged at a Chapter Meet, it lost a total of 15 points on the exhaust system, 7 on condition and 8 on originality. I've got extremely rusty pipes, replacement mufflers with wrong part #'s and "Inlet" marked on them, and a clamp between the muffler and pipe (instead of welding). Exhaust tips are service replacement with part #'s on them.
It seems Corvette Central has a pretty decent reproduction available for $325. 2 1/2" pipes all the way back, welded to correct configuration mufflers. Pipes are flattened out under differential just like originals.
So here are the questions:
1) Should I get aluminized or carbon steel? Hate to watch it rust again and get banged for condition.
2) If a magnet sticks to the aluminized do I still get a deduction on originality?
3) How much do I lose from the mufflers not having the embossed part #'s? They'll have no writing on them at all.
4) I can buy a pair of NOS exhaust tips for $600. Seems awfully steep. How many points do I lose just keeping my service replacements?
5) Which exhaust vendors have others used with good judging results?
6) Being that it's a '73, Will Lyle be the first to answer?

[Peter G.]

Re: Judging LS4 exhaust

Bill..

I've been told that Allen Exhaust Systems have the best restoration exhaust system for my '73 LS4. I don't know much about them except I saw their booth at Kissimmee the last two years that I have gone. Also I once saw their add in the Driveline. They have our exhaust system in steel, aluminum and I believe stainless metals.

I want to do my exhaust system complete as I have some type of aftermarket "turbo" mufflers on the car and '70-'72 repo tips with extra hangars.

I'll be watching this posting.

Thanks for your post.

[William M.]

Re: Judging LS4 exhaust

Bill..

I've been told that Allen Exhaust Systems have the best restoration exhaust system for my '73 LS4. I don't know much about them except I saw their booth at Kissimmee the last two years that I have gone. Also I once saw their add in the Driveline. They have our exhaust system in steel, aluminum and I believe stainless metals.

I want to do my exhaust system complete as I have some type of aftermarket "turbo" mufflers on the car and '70-'72 repo tips with extra hangars.

I'll be watching this posting.

Thanks for your post.

I checked out Allen's website. The picture they have of their welded 73 big block system has incorrect hideaway mufflers. They should be round. Also, the text says all their 73-74 exhaust systems feature hideaway mufflers.

[Harmon C.]

Re: Judging LS4 exhaust

I have a 73 LS4 auto. When it was judged at a Chapter Meet, it lost a total of 15 points on the exhaust system, 7 on condition and 8 on originality. I've got extremely rusty pipes, replacement mufflers with wrong part #'s and "Inlet" marked on them, and a clamp between the muffler and pipe (instead of welding). Exhaust tips are service replacement with part #'s on them.
It seems Corvette Central has a pretty decent reproduction available for $325. 2 1/2" pipes all the way back, welded to correct configuration mufflers. Pipes are flattened out under differential just like originals.
So here are the questions:
1) Should I get aluminized or carbon steel? Hate to watch it rust again and get banged for condition.
2) If a magnet sticks to the aluminized do I still get a deduction on originality?
3) How much do I lose from the mufflers not having the embossed part #'s? They'll have no writing on them at all.
4) I can buy a pair of NOS exhaust tips for $600. Seems awfully steep. How many points do I lose just keeping my service replacements?
5) Which exhaust vendors have others used with good judging results?
6) Being that it's a '73, Will Lyle be the first to answer?

I lost three points on originality on my small block welded system with period correct clamps. Note said no muffler logo aluminized. Don't expect the same results as all judges are different.
#1 I would use aluminzed
#2 yes
#3 one point but you never know for sure
#4 I would say one point as the judge needs to leave room for the100% correct part. I have a NOS set you can have for $500.
#5 Corvette Central is my first choice Voulenteer second,and make the weld at the muffler myself saves $100.
#6 Not this time!!

[William M.]

Re: Judging LS4 exhaust

I'll probably go with Corvette Central. Should I black out the mufflers like the JG says?

[Harmon C.]

Re: Judging LS4 exhaust

yes but only the bottom side

[William M.]

Re: Judging LS4 exhaust

Judging Guide doesn't mention what markings should be on clamps and hangers. Where's the best place to buy authentic exhaust hardware?

[William M.]

Re: Judging LS4 exhaust

Paragon has these clamps:

Part # 2587K: 2" Exhaust tip to muffler clamp & "U" bolt
An exact repro of flat type "U" bolt w/ notched inside surface & raised "K" logo, 5/16" 18 threads, "ears" on the side as original and stamped "2171". Includes flanged nuts and bracket.

Part # 2586K: 2 1/2" Guillotine style exhaust clamp used at center union of exhaust pipes.

Can anyone verify if these are correct?

[Harmon C.]

Re: Judging LS4 exhaust

They should be correct for most judges.

[Peter G.]

Re: Judging LS4 exhaust

Bill, I was working on my exhaust tips today and trying to make the exhaust tips work with aftermarket mufflers that have been "Bubba" fixed and decided it was time for the complete exhaust system for my LS4.

Did you get a new system? What did you decide on? Where did you purchase the system from and how long did it take for delivery, price etc?

Info from Lyle is always the best!

[Russ S.]

Re: Judging LS4 exhaust

Paragon has these clamps:

Part # 2587K: 2" Exhaust tip to muffler clamp & "U" bolt
An exact repro of flat type "U" bolt w/ notched inside surface & raised "K" logo, 5/16" 18 threads, "ears" on the side as original and stamped "2171". Includes flanged nuts and bracket.

Part # 2586K: 2 1/2" Guillotine style exhaust clamp used at center union of exhaust pipes.

Can anyone verify if these are correct?

Correct me if I am wrong guys but I believe 73 did not use guillotine clamps but the standard two sided flange with the U shaped threaded rod going between the two sides of the flange. RS

[Alan S.]

Re: Judging LS4 exhaust

Hi Peter,
With-in the last couple of months there has been a very informative thread about the exhaust systems available.
There was discussion about the the points vs $$ issue, and the pluses and minuses of the various supplier's systems.
I don't remember the title of the thread, but if you search 'exhaust systems' I'll bet you can find it pretty quickly. I remember that Paul Oslansky was part of it so you might want to search his recent posts.
I believe it was mainly about 68-72 systems but I think you'll find it interesting too.
Regards,
Alan

[William M.]

Re: Judging LS4 exhaust

Bill, I was working on my exhaust tips today and trying to make the exhaust tips work with aftermarket mufflers that have been "Bubba" fixed and decided it was time for the complete exhaust system for my LS4.

Did you get a new system? What did you decide on? Where did you purchase the system from and how long did it take for delivery, price etc?

Info from Lyle is always the best!

I went with the Corvette Central system. Lost 4 points out of 50 at last year's National Convention. 2 points for aluminized pipes and 2 points for mufflers with no markings. Don't recall the price (it would be on their website) and delivery was quick.

[Peter G.]

Re: Judging LS4 exhaust

Thanks Bill. Your exhaust from the pic looks really great.

Mine system is ordered and it should come next week and the installation soon after that. My biggest interest is the new sound of the system with the factory styled OEM round mufflers as the car has had aftermarket "Turbo" mufflers on since I purchased the car.