Stock Cat heat shield?

[CrammerGram69]

Yes, the "older" ones got bolted on with small screws, just like the later ones. Again, they may be bolted up to the same spots. I'm just not familiar with what an 80-81 shield looks like.

Screws are hex washer head style, M4.2x1.41x10. GM p/n 11503617, superseded to 11515959.

Gotcha. Thx for the heads-up on the part #s. massive help! I had never seen or heard they were used. until my Father pointed it out a few nights ago. I will admit, strange how they start off with #255. I have a good amount of experience in nos parts research... but all of them i know of from the mid-70s to early 80s was #140. what changed?

 

[ELCAM]

Every part number is a different shaped heat shield but I believe they all mount the same. The earliest design is also the same as the 76-79 X and F bodies.

 

[69hurstolds]

There's also some double holes and slotted holes in the 619 shield, so it may just be they were availed to fit other cars or to make up for slop in the bracket location tolerances on the floorboards. Who knows?

 

[CrammerGram69]

V

Every part number is a different shaped heat shield but I believe they all mount the same. The earliest design is also the same as the 76-79 X and F bodies.

Very interesting for sure. I would love too see photo's if anyone can dig some up.

 

[69hurstolds]

I'm not 100% on this, but I think the 619 is a slightly different shape than the factory style. It's been a while since I've been under any of my cars, but the little "tab" doesn't seem like it was there on the factory ones. Who knows? I'm not sure though.

 

[79 USA 1]

This is odd... Both my 1979 Monte Carlo's had the large "Dutch Oven" style converters as did a 79 Malibu Classic I had years ago. None had a heat shield above the converter. All 3 were 267 V-8 cars built in Oshawa and looking at the Monte Carlo's I see no stand offs for a bolt on shield. Under the passenger side carpet on all 3 cars was a heavy insulated plastic bag of what could have been asbestos for all we know that keep the carpet from burning and helped to trap moisture and rot the front floor pan. Was the shield just a V-6 item or did the shield come into play after the dutch oven converters were replaced?

 

[Ugly1]

I have one you can have. Off an 81’ 4.4L ElCamino. I’ll get a picture shortly. Just have to pay the ticket to get it to you if it works.

 

[69hurstolds]

Parts books don't support 78-79 A-body for heat shields, and the one 1978 original car I looked under I don't recall seeing a heat shield above the massive cat converter. Shields were used from 1980 until the end. Unless it was a diesel with no cat.

I'm thinking they didn't even have one for 78-79.

 

[pagrunt]

I know it's hard to fathom, but I actually have an NOS heat shield in my parts stash. P/N 25512619. Fits a plethora of G-body cars, but it's 82-up.

80-81 was 25505917 superseded to 25507682. Now, I can't find anything concrete to say the 619 is the same as the 917/682 shields. V6 or V8, didn't make any difference on engines.

Unfortunately, those part numbers don't correlate to each other, so I don't know what, if any differences there are.

Best to get the dimensions between the screw holes and ask the seller if that correlates to the holes in his shield.

Not being something I really paid attention to but could the difference be changing from the pellet type converters? I do know the early cars had a heat shield that the service manual shows how to replace them on the cat body along with replacing the pellets.

 

[79 USA 1]

Not being something I really paid attention to but could the difference be changing from the pellet type converters? I do know the early cars had a heat shield that the service manual shows how to replace them on the cat body along with replacing the pellets.

That was my thought.
The "insulation bag" that was in the front passenger floor pan under the carpet pad above where the converter would sit. All 3 of my 79 cars had this bag which was a clear plastic about 5 mil (Double construction garbage bag) had what looked like fiberfill quilt batting wrapped around a thin white fiberboard about the thickness of two layers of a cereal box.
My 88 Monte SS does not have the plastic bag but does have a bolt on shield as did my 86 El Camino.