Originality of Side Dual Exhaust

[Robert K.]

Is there a good way to determine the originality of a set of side dual exhaust covers. I know that they're supposed to have a thermal barrier in the inside of them (glued / fastened with screws/ rivited, etc.? In looking at other posting on this subject, I find that some refer to this barrier as grey in color while others refer to it as black in color - is it just a piece of molded black fiberglass to fit inside the cover? The AIM shows #3872283 - 84 for the cover assembly - does that number appear anywhere on the sidepipe? How many holes are in the covers for fastening to the car? I have the AIM and am looking at that (UPC N-14) and it shows that the bracket has a screw and a rivet. Does anyone know what type (material/sixe etc. these rivets were? Where was the bracket assembled to the cover?

Any history and or help with other references would be appreciated.

I have a '67 L71 and am trying to determine if the sidepipe covers on the car are original.

Thanks you for your help.

[Joe C.]

Re: Originality of Side Dual Exhaust

Is there a good way to determine the originality of a set of side dual exhaust covers. I know that they're supposed to have a thermal barrier in the inside of them (glued / fastened with screws/ rivited, etc.? In looking at other posting on this subject, I find that some refer to this barrier as grey in color while others refer to it as black in color - is it just a piece of molded black fiberglass to fit inside the cover? The AIM shows #3872283 - 84 for the cover assembly - does that number appear anywhere on the sidepipe? How many holes are in the covers for fastening to the car? I have the AIM and am looking at that (UPC N-14) and it shows that the bracket has a screw and a rivet. Does anyone know what type (material/sixe etc. these rivets were? Where was the bracket assembled to the cover?

Any history and or help with other references would be appreciated.

I have a '67 L71 and am trying to determine if the sidepipe covers on the car are original.

Thanks you for your help.

Robert,

I'm no expert here, but, I think that I can be certain that "original", or at least those covers produced fairly early on, had DARK grey composite insulators. NOT BLACK, but colored similarly to your spare tire tub (dark grey). The insulators were bonded to the aluminum covers with ordinary polyester bonding adhesive. There are 2 sections to each insulator, a curved forward section which insulates the head pipe, and a straight section, which insulates the muffler. I'm not sure about casting numbers, and don't know whether that is a valid point to look at for verification. There are 6 holes in the covers for fastening, 2-3 of which are slotted. Each bracket is fastened to the cover with two round headed aluminum rivets.

Joe

[Wayne M.]

Re: Originality of Side Dual Exhaust

.... I know that they're supposed to have a thermal barrier in the inside of them (glued / fastened with screws/ rivited, etc.? In looking at other posting on this subject, I find that some refer to this barrier as grey in color while others refer to it as black in color - is it just a piece of molded black fiberglass to fit inside the cover? The AIM shows #3872283 - 84 for the cover assembly - does that number appear anywhere on the sidepipe?

Robert -- here's a shot of the LH cover at the junction between the curve and the straight. Shows some of the numbers molded into the fiberglass. Note that there is a sandwich of both inner and outer mouldings of fiberglass with an air gap between.

These are (probably) service as the (then) owner installed a side pipe setup around 1983. The outer shield (visible through the slots) is a semi-gloss black, so it must have been painted on that one surface (IMO).

[Robert K.]

Re: Originality of Side Dual Exhaust

Wayne and Joe,

Thank you for your replies! I looked at mine again today and compared them to your photos and also found the number on the long section (38975, while the other side is 38974) that shows up in one of your photos! What was confusing me was the fact that I am missing the "curved" section of insulation on both sides - I didn't know that was present. I also notice the "bonding/glue) that you spoke of and can see in various places where it has "oozed" out!

Do either of you know anyone who is restoring these assemblies? On one of the assemblies, the previous owner has drilled through the cover (aluminum) and into the insulation (2 places) and put 1/4 x 24 screws in place (I suppose this was because the glue was coming loose and it was making noises (rattling)...... Any thoughts on repair? They would still be visible even after the body side moldings are attached.

Thanks again for your help!

[Rick S.]

Re: Originality of Side Dual Exhaust

I used JB Weld as an adhesive to reattach my insulators about 2 years ago and that has worked w/o any issues. In regards to the previous owner (Bubba) drilling thru the cover, did he drill thru the anodized area or the gray area? If the gray area you might be able to patch and repaint that yourself. I believe there have been previous posts about which color or brand of paint to match.

Rick

[Joe C.]

Re: Originality of Side Dual Exhaust

Wayne and Joe,

Thank you for your replies! I looked at mine again today and compared them to your photos and also found the number on the long section (38975, while the other side is 38974) that shows up in one of your photos! What was confusing me was the fact that I am missing the "curved" section of insulation on both sides - I didn't know that was present. I also notice the "bonding/glue) that you spoke of and can see in various places where it has "oozed" out!

Do either of you know anyone who is restoring these assemblies? On one of the assemblies, the previous owner has drilled through the cover (aluminum) and into the insulation (2 places) and put 1/4 x 24 screws in place (I suppose this was because the glue was coming loose and it was making noises (rattling)...... Any thoughts on repair? They would still be visible even after the body side moldings are attached.

Thanks again for your help!

Robert,

AFAIK, nobody is restoring these covers. It is WAAAAYYYYYY too labor intensive. Ask me how I know!
Here's where you can get your insulators:

http://www.parts123.com/parts123/yb.dll?parta~partsort

Yes, you can use JB weld, epoxy cement, or many other substances. I'll tell you though, that they were originally attached with dark grey or black polyester bonding adhesive.

Here is another shot of my covers (before I bonded the new insulators to the insides):

[Robert K.]

Re: Originality of Side Dual Exhaust

Thanks again to all who replied - looks like I have some work to do!!