1971 LT-1 Service Replacement Exhaust

[Mick D.]

Hi Folks,

I'm getting my 1971 LT-1 ready for regionals in the future, and so there are a few key areas where points were lost in Chapter Judging that I'd like to address. I know that there are many knowledgeable LT-1 owners on here, so would love to get their opinions.

My mufflers and exhaust are non-original (easy to see from the non-swaged header pipes where it goes from 2 to 2.5 inch), which I knew, but what I am unclear on is if any parts are a service replacement. In particular, the TIMJG 6th edition mentions

"LT1 service replacement front header pipes have smaller diameter pipes welded into larger ones. They also have additional clearance around the transmission on the driver-side pipe to fit vehicles with automatic transmissions"

This reads to me that non-swaged pipes but which are actually a service replacement which is welded, could warrant a lesser deduct than 'any old welded 2-2.5" pipe', is that correct?

I'd appreciate any comments on work I could do on my exhaust that could help me with points. (If you have a leads on original LT-1 exhaust parts that I could purchase, I would appreciate it also)


Here are some exhaust photos, I apologize that there is not a photo on a lift - I just do not have availability of one right now.

Photos of exhaust

Mick

[Edward J.]

Re: 1971 LT-1 Service Replacement Exhaust

019587A0-748C-475E-8689-B61B72ED44EF.jpg3B1C6B38-B330-4D41-AEB2-2BE7146CA9FA.jpg5996FCC3-1528-4953-A577-F1C64DC47773.jpgMick, here are some pics of a front pipes from a Lt1. Note the crinkle in the area of the bends. You will find that that most venders do not make an exhaust correctly configured,So many differences between original and aftermarket venders.

[Mick D.]

Re: 1971 LT-1 Service Replacement Exhaust

Appreciate these photos Edward - I'd love to fit the "correct" swaged version to my LT-1 if I could find a set. I believe that may be difficult.

[ATTACH=CONFIG]116638[/ATTACH][ATTACH=CONFIG]116639[/ATTACH][ATTACH=CONFIG]116640[/ATTACH]

Mick, here are some pics of a front pipes from a Lt1. Note the crinkle in the area of the bends. You will find that that most venders do not make an exhaust correctly configured,So many differences between original and aftermarket venders.

[Gary B.]

Re: 1971 LT-1 Service Replacement Exhaust

If money was no object... Gardner front pipes, in natural bare steel (not aluminized) are very accurate. Just DO NOT have him put wrinkles in the bends of the front pipes. Make them wrinkle free. Speaking of front pipes still, I don't think they started adding wrinkles in those until every late production 1972. It started with the RH pipe, then (I think) last few weeks of 1972 production the LH side used them. Gardner will not sell just front pipes. They sell the whole system....

Still talking front pipes, automatic and manual transmissions are bent different. Manual transmission pipes hug the transmission, then bend over towards the holes in the crossmember. Automatic transmission pipes, drop down from the exhaust manifolds, goes almost straight back along the trans, then bends towards the hole in the crossmember. I've seen swedged 2-1/2" pipes bent for an automatic. I suspect only a well seasoned judge would see that.

Gardner exhaust mimics Arvin exhaust. The wrinkles are coarse, wide wrinkles similar to Arvin. Through 72, GM used Walker exhaust exclusively for the rear pipes. The wrinkles are a finer pitched, narrower. Like the above photo's. All the bends used wrinkles, even just before the muffler.

GM used double wall pipes, while Walker over the counter used single wall pipes. If you tap them with a pen, flashlight, etc... you'll notice a dull thud versus a sharp ring. Dull thud is double wall.

Aluminized pipes are a standard deduction. Natural steel pipes would be subject to CDCIF. Usually Configuration is different, so a 20% deduction. If they are not welded correctly, you could get another 20% deduction (installation). Some judges will want to also do a 20% deduction for Date, but exhaust is not dated.

A few years ago, I had to replace the exhaust on my 70 for the second time. I threw the Gardner center pipes away, put the mufflers in storage. Used just the front pipes. I had bought Walker, over the counter pipes, a few years ago from a very old NAPA store. I think I bought 4-sets. (as Joe would say, none for sale). I used an old mid-80's set of mufflers with the part number and date. I erased the part number and date, left the "W". The exhaust looks original. I've never had the car judged since 1988. My daughter can sell the car if she wants when I'm dead.

You can convert the mufflers to look like original equipment. But it takes a lot of creative work. I've done a few sets, they have passed judging. Just think outside the box a little.

Start scrounging old part stores that Have been around for 50-years. You might find some old pipes.

Gary Bosselman