http://www.summitracing.com/parts/wlk-47597

I cannot verify from Walker or Summit that it is actually 3"

 

Dyno Don referenced a different part number for the 3" I pipe in his thread: '3" Catback...'

Search threads started by him, I am unable to copy a link now.

 

It says the OD is 2.5 in the add

 

https://www.thirdgen.org/forums/exha...3-catback.html

 

I have that on my car and it is 2.5"

 

Yeah, it does, but's different than the other 2.5" pipe they sell for the low po engines. This one is supposed to be for code G, (L69) and code F (LB9).

 

Thanks! I'll look it over.

 

 

Part number change may just have something to do with how it attaches to the cat?

 

The LG4 and TPI attach to the Cat with a two-bolt ball and socket fitting. The L69 uses a four bolt flat flange. An I-pipe that fits a code G MAY NOT fit a code F. Code G will have a four-bolt connection from the Y to the Cat. TPI has a slip fit connection. I DO NOT know if some of the early TPI motors used the same exhaust (Y/CAT/I) that the L69 used. All I've seen did not.

I've installed a few of these inexpensive Walker systems over the years. They are a significant upgrade over the stock LG4 system but not 3". I've bought them when they've offered the $50 rebate and netted the cat back for under $150.

For anything over a mild 305 I'd follow Dyno Don's recommendation, although I do not know why you could not use the third gen specific outlet that has the boss to attach to the factory mount.

 

After perusing Dyno Dave's thread, it appears that those pipes need some fab work, ie., no 4 bolt flange, etc.

Walker does offer a 2.75" pipe, 46669 which is listed as a 2.5" pipe at Summit, but it doesn't have the 4 bolt flange.

 

My '85 TPI "F" has the 4 bolt flange. I'm looking for a direct replacement for the factory I-pipe.

 

I wound up editing my above post thinking that perhaps the L69 exhaust was used on early TPIs. Makes sense. I've installed both systems and the L69 is larger and stouter by far than the TPI.

 

You just have the flat 4 bolt flange ?
Is it something like the TTA uses?
They have the 4 bolt cat buuuut it has a adapter to go to the 2 bolt ball and socket I pipe.

 

The one in the first post, 47597 is listed as an HO for both the '85 L69 and LB9. But it has the same 2.5" diameter listed as the LoPo version.

 

I'm not 100% sure.

 

https://www.thirdgen.org/forums/exha...aust-pics.html

 

I believe this is the one you're considering:

 

I'm getting the impression that I either need to patch up the one I have or have one made if I want the proper diameter.

 

The 4-Bolt 47597 Int Pipe Was Only Used On 1984,1985 Model Years.

 

I think that's the one. Do you have access to that one? If so, can you measure the diameter for me?

 

I know it's not 3". Will measure od tonight.

 

Thanks. I'd be curious if it actually 2.75" and advertised as 2.5".

 

Measures 2 1/2 OD.

Replaced the LG4 I pipe that measures 2 1/4 OD.

Let us know if you find a bigger option that connects to the L69 cat flange.

Unfortunately the L69 Y would not be easily modified to fit the 3" slip fit cat. It is oval where the flange connects. It would have to be cut and a round section added.

 

Okay, thanks for that. Just what I needed to know. I believe I'm going to have an exhaust shop create another 2.75" pipe section to replace the damaged section.

 

A 88 350 car would have the correct pipe except the converter flange. Sould be able to go that route fairly easy.