71 LT-1 Exhaust same as Service Replacements for 67-68 and 71' 454?

[Mick D.]

Hey Folks,

I'm on a bit of a campaign to research original exhaust data for my LT-1.

I wanted to clarify a few things, and once I have enough data on it, maybe I'll put this into a spreadsheet or something.

First, below is a screen shot of the 53-82 parts manual. It shows for instance that a 454 has some similar service replacement (at least by 1982) parts to an LT-1 (in yellow), and then ones i highlighted in blue are also listed under 67-68. Prior to finding this manual, I thought that the LT-1 exhaust was extremely specific to that model.

lt1-parts.jpg

Pre 71

lt1-parts2.jpg

I know that by 82 these parts some of these parts had new part numbers - So my question is - is there a definitive list of the 'lifecycle' of original through service LT-1 service exhaust parts? I'm trying to find out what the total 'surface area' is when searching for these kind of parts.

Side question : Is there software or books that show the obsoletion of parts (like 'replace by xxxx')?

Thanks as always,

Mick

[Mark F.]

Re: 71 LT-1 Exhaust same as Service Replacements for 67-68 and 71' 454?

Hey Folks...First, below is a screen shot of the 53-82 parts manual...Mick

Mick,
your screenshot did not come thru (at least not on my end)

[Justin S.]

Re: 71 LT-1 Exhaust same as Service Replacements for 67-68 and 71' 454?

Mark ,
I'm not certain a screen shot would matter. I wouldn't know how an exhaust system for a big block would work on a small block.

[Mark F.]

Re: 71 LT-1 Exhaust same as Service Replacements for 67-68 and 71' 454?

Mark, I'm not certain a screen shot would matter. I wouldn't know how an exhaust system for a big block would work on a small block.

Justin,

Agreed
I was just curious to see what the document said
My '67 BB N11 is 2-1/2" - I'm assuming a '71 LT1 is a 2" system, right ?

[Mick D.]

Re: 71 LT-1 Exhaust same as Service Replacements for 67-68 and 71' 454?

Folks - sorry I just added the pictures. You can see there seems to be some interchange between years.

[Justin S.]

Re: 71 LT-1 Exhaust same as Service Replacements for 67-68 and 71' 454?

Michael,
I can see the possibility of the rear sections being interchangeable but never the front sections.

[Joe L.]

Re: 71 LT-1 Exhaust same as Service Replacements for 67-68 and 71' 454?

Hey Folks,

I'm on a bit of a campaign to research original exhaust data for my LT-1.

I wanted to clarify a few things, and once I have enough data on it, maybe I'll put this into a spreadsheet or something.

First, below is a screen shot of the 53-82 parts manual. It shows for instance that a 454 has some similar service replacement (at least by 1982) parts to an LT-1 (in yellow), and then ones i highlighted in blue are also listed under 67-68. Prior to finding this manual, I thought that the LT-1 exhaust was extremely specific to that model.

[ATTACH=CONFIG]116735[/ATTACH]

Pre 71

[ATTACH=CONFIG]116736[/ATTACH]

I know that by 82 these parts some of these parts had new part numbers - So my question is - is there a definitive list of the 'lifecycle' of original through service LT-1 service exhaust parts? I'm trying to find out what the total 'surface area' is when searching for these kind of parts.

Side question : Is there software or books that show the obsoletion of parts (like 'replace by xxxx')?

Thanks as always,

Mick

Mick-------


The 6 digit part numbers are later SERVICE part numbers. They will work just fine for the applications listed but they differ in some aspects of configuration.

In answer to your question, it's like this:

Forward Pipes:

1970-72 LT-1 used the same forward pipes as all 1968 small block with manual transmission. They were NOT the same as any 1963-67 small block or any 1965-74 big block.

Rear Pipes:

1970-72 LT-1 used the same rear pipes as all 1968 Corvette applications, small block or big block. However, keep in mind that the rear pipes available in SERVICE were shorter than PRODUCTION rear pipes since an allowance had to be made for the SERVICE muffler extension pipes.

Mufflers:

All SERVICE mufflers (except N-11) have a forward extension. PRODUCTION mufflers had the rear pipes welded directly to the mufflers.

1963-65 2-1/2" mufflers are the same as all 1968 and 1970-72 LT-1 EXCEPT the muffler hanger bracket is different. The last available GM mufflers for 2-1/2" 1963-65 and all 1968 and 70-72 LT-1 had DUAL brackets to SERVICE all.

[Mick D.]

Re: 71 LT-1 Exhaust same as Service Replacements for 67-68 and 71' 454?

How on earth you built all this knowledge to be to hand I'll never know. Thanks Joe.

If in future I am looking to know which parts have been obsoleted for a particular part number, is there a good website for that? Or is it only in books and literature? Just curious.

Mick-------


The 6 digit part numbers are later SERVICE part numbers. They will work just fine for the applications listed but they differ in some aspects of configuration.

In answer to your question, it's like this:

Forward Pipes:

1970-72 LT-1 used the same forward pipes as all 1968 small block with manual transmission. They were NOT the same as any 1963-67 small block or any 1965-74 big block.

Rear Pipes:

1970-72 LT-1 used the same rear pipes as all 1968 Corvette applications, small block or big block. However, keep in mind that the rear pipes available in SERVICE were shorter than PRODUCTION rear pipes since an allowance had to be made for the SERVICE muffler extension pipes.

Mufflers:

All SERVICE mufflers (except N-11) have a forward extension. PRODUCTION mufflers had the rear pipes welded directly to the mufflers.

1963-65 2-1/2" mufflers are the same as all 1968 and 1970-72 LT-1 EXCEPT the muffler hanger bracket is different. The last available GM mufflers for 2-1/2" 1963-65 and all 1968 and 70-72 LT-1 had DUAL brackets to SERVICE all.

[Mark E.]

Re: 71 LT-1 Exhaust same as Service Replacements for 67-68 and 71' 454?

[/U]1970-72 LT-1 used the same forward pipes as all 1968 small block with manual transmission. They were NOT the same as any 1963-67 small block or any 1965-74 big block.

Aren't LT-1 forward pipes 2 1/2" and uniquely swaged down to the manifold?

[Mick D.]

Re: 71 LT-1 Exhaust same as Service Replacements for 67-68 and 71' 454?

Hey Mark, correct they are swaged from 2" out to 2.5" shortly after they exit the manifold.

This picture below is from an EBay advertisement which stated

"NOS Front Exhaust Pipe for 1966-1967 Corvette - P/N 334926 - Right Passenger"

s-l1600.jpg

It seemed to have a swage aswell, which is what started me down the path of - 'which other cars have this part', Joe seems to have cleared it up for me above. Prior to this, I did not realize the 'special' LT-1 exhaust parts also existed on other non-LT1 cars back to the sixties.

[Mark E.]

Re: 71 LT-1 Exhaust same as Service Replacements for 67-68 and 71' 454?

Hey Mark, correct they are swaged from 2" out to 2.5" shortly after they exit the manifold.

This picture below is from an EBay advertisement which stated

"NOS Front Exhaust Pipe for 1966-1967 Corvette - P/N 334926 - Right Passenger"

[ATTACH=CONFIG]116738[/ATTACH]

It seemed to have a swage aswell, which is what started me down the path of - 'which other cars have this part', Joe seems to have cleared it up for me above. Prior to this, I did not realize the 'special' LT-1 exhaust parts also existed on other non-LT1 cars back to the sixties.

Isn't this swage unique to LT-1?

[Joe L.]

Re: 71 LT-1 Exhaust same as Service Replacements for 67-68 and 71' 454?

How on earth you built all this knowledge to be to hand I'll never know. Thanks Joe.

If in future I am looking to know which parts have been obsoleted for a particular part number, is there a good website for that? Or is it only in books and literature? Just curious.

Mick-------


I can tell you that all of the exhaust system, pipes and mufflers, have been long-since GM discontinued. This includes both the original part numbers as well as all supercessive part numbers. The part numbers you show in the table you posted were the last available part numbers. When they "died", that was it.

[Mick D.]

Re: 71 LT-1 Exhaust same as Service Replacements for 67-68 and 71' 454?

Isn't this swage unique to LT-1?

I mean... I used to think it was, until I started seeing these non-LT-1 parts above (that's a swage above right?)

[Joe L.]

Re: 71 LT-1 Exhaust same as Service Replacements for 67-68 and 71' 454?

Isn't this swage unique to LT-1?

Mark------


1970-72 LT-1 and all 1968 small blocks originally used the exact same forward pipes. Also, I neglected to previously mention, the same right side forward pipe was used for 1966-67 L-79.

Later L-82 and supercessive for the above (6 digit part numbers) used a different pipe diameter reduction.

[Mick D.]

Re: 71 LT-1 Exhaust same as Service Replacements for 67-68 and 71' 454?

Thanks Joe - I was just asking as sometimes when I am searching for used parts I search the 'last' number but then find that someone has only listed the number stamped on the part, which is usually the 'original' GM number. Sometimes its the other way around, i know the 'original' but not the 'last' or 'in-between' numbers.

Mick-------


I can tell you that all of the exhaust system, pipes and mufflers, have been long-since GM discontinued. This includes both the original part numbers as well as all supercessive part numbers. The part numbers you show in the table you posted were the last available part numbers. When they "died", that was it.