hood insulation
Thread Starter
Instructor
Joined: Feb 2009
Posts: 178
Likes: 2
From: York UK
hood insulation
Hi Forum,
The hood is off my '69 350 just now as I'm getting the car re-sprayed. I thought I'd take the opportunity to fit insulation underneath for sound and heat. Apart from the three split rings, there seems to be no indication of insulation having been fitted before. There's no sign of adhesive for instance. I was going to stick down a half inch thick layer of re-constituted foam - it looks dense enough but I covered it with vinyl and it has a lumpy appearance which doesn't look good. What's the original material, and is it even important to fit it?
Thanks, Barry.
The hood is off my '69 350 just now as I'm getting the car re-sprayed. I thought I'd take the opportunity to fit insulation underneath for sound and heat. Apart from the three split rings, there seems to be no indication of insulation having been fitted before. There's no sign of adhesive for instance. I was going to stick down a half inch thick layer of re-constituted foam - it looks dense enough but I covered it with vinyl and it has a lumpy appearance which doesn't look good. What's the original material, and is it even important to fit it?
Thanks, Barry.
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
Race Director
Joined: Oct 2000
Posts: 12,680
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From: Shamong, NJ
Some 69's came with a short insulation pad, on the front underside of the hood. It only covered about the first 25-30% of the hood. The insulation was made out of 1/2" thick, black fiberglass matting, and was held on by 3 retainers.
I can't really say why some cars got the insulation blanket, and others didn't. Big block or small block, with or without air, there doesn't seem to be any correlation, though I think it was mainly found on cars earlier in the production run?
Other than the portion of 69 production that came with the small insulation blanket, no other 68-72's came with any hood insulation. 73-77 Corvettes all came with a full insulation blanket (73-75's have a hole in the middle for the ram air), and 78-79's came with a blanket that covered the front half of the hood. No insulation was used on 80-82 hoods.
The small 69 blanket is available from most of the Corvette vendors. If you want a full size blanket, you should be able to use the 76-77 insulation, on your 69 hood.
I can't really say why some cars got the insulation blanket, and others didn't. Big block or small block, with or without air, there doesn't seem to be any correlation, though I think it was mainly found on cars earlier in the production run?
Other than the portion of 69 production that came with the small insulation blanket, no other 68-72's came with any hood insulation. 73-77 Corvettes all came with a full insulation blanket (73-75's have a hole in the middle for the ram air), and 78-79's came with a blanket that covered the front half of the hood. No insulation was used on 80-82 hoods.
The small 69 blanket is available from most of the Corvette vendors. If you want a full size blanket, you should be able to use the 76-77 insulation, on your 69 hood.
Thread Starter
Instructor
Joined: Feb 2009
Posts: 178
Likes: 2
From: York UK
insulation dilemma
Hi Guys, there's more to insulation than I thought! I didn't know some types were designed to drop onto the engine in the event of a fire to smother it. My car obviously never had insulation. There are some quite serious bubbles which have developed over the years, but they're only on one side, so I think it's more to do with moisture getting in after an amateur re-spray than heat damage. I bet the heat on a sunny day in Arizona is greater than the heat from the engine. I was going to stick on some foam insulation but if it came down or there wasn't enough clearance it would be difficult to scape away the adhesive from under the hood. I might go for the option of the insulation just above the fan as it's held on by the 3 retainers. GM obviously knew that the absence of insulation wouldn't damage the paint. Thanks, Barry.
Race Director
Joined: Jul 2001
Posts: 15,892
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C3 Corvettes got insulation for one reason and one reason only- to meet noise pollution regulations.
