Under hood insulation
Thread Starter
Intermediate
Joined: Nov 2013
Posts: 34
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Under hood insulation
Replacing the under hood insulation. The insulation has a unfaced side (fuzzy side) and a faced (smooth shiny side). Question ?. Which side of the insulation goes down towards engine compartment ?
Instructor
Joined: Feb 2015
Posts: 194
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From: Tennessee
The fuzzy side faces the engine. It didn't seem appropriate why I installed mine, but I discovered the hood isn't symmetrical on my '73. Note the hood latches are not parallel, one is further forward than the other.
Instructor
Joined: Nov 2018
Posts: 110
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From: Oregon, Ohio
Thanks for that post, I had the same question. Seems on this board there are both answers, shiny side up/down, but reading this post saved the day. You are righto, my 73 is asymmetrical, as the picture shows, and after looking at the new insulation, yes the driver side has a notch to fit the latch, it's closer to the rear. Fortunately I still had the original steel retainers which I de-rusted and repainted flat black. Weatherstripping is next.
Team Owner
Joined: Jan 2006
Posts: 37,637
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From: Crossville TN
From an engineering standpoint, the foil side should be toward the engine. The foil is there to reflect radiant heat. Not much need to reflect radiant heat from the underside of the hood....
But, I'm sure that GM had it installed the other way.
I would want the foil down and the fuzzy insulation between the heat and my hood. But.....that's just the way I see it.
But, I'm sure that GM had it installed the other way.
I would want the foil down and the fuzzy insulation between the heat and my hood. But.....that's just the way I see it.
Race Director
Joined: Oct 2000
Posts: 12,657
Likes: 3,117
From: Shamong, NJ
From an engineering standpoint, the foil side should be toward the engine. The foil is there to reflect radiant heat. Not much need to reflect radiant heat from the underside of the hood....
But, I'm sure that GM had it installed the other way.
I would want the foil down and the fuzzy insulation between the heat and my hood. But.....that's just the way I see it.
But, I'm sure that GM had it installed the other way.
I would want the foil down and the fuzzy insulation between the heat and my hood. But.....that's just the way I see it.
I've never been sure if the blankets were installed to reduce heat, or to reduce engine noise. If it was there for noise reduction, then the insulation side would be very effective at absorbing engine noise.
Burning Brakes
Joined: Oct 2013
Posts: 1,114
Likes: 520
From: McClellandtown, Pa.
The GM hood blankets don't have a foil side. One side is the slightly course insulation material, and the other side is a smooth black backing.
I've never been sure if the blankets were installed to reduce heat, or to reduce engine noise. If it was there for noise reduction, then the insulation side would be very effective at absorbing engine noise.
I've never been sure if the blankets were installed to reduce heat, or to reduce engine noise. If it was there for noise reduction, then the insulation side would be very effective at absorbing engine noise.
Yeah, for sure no foil on the 73-75 insulation. You are correct when you mention the two different textures on the reproduction 73-75 Insulation. ( I think the OP threw readers off when he said 'shiny side'!) FYI, the smooth side does face the engine on the original OEM 73-75 Hood Insulation. It was all about eliminating noise starting with the '73. That was also first year for more sound deadening material on all inner door/body panels as well.
Examples below show both sides of the repro Insulation and the last photo is the OEM 73-75 Insulation.
Jimmy
Last edited by Tooch1; Nov 8, 2019 at 07:55 AM.
Melting Slicks
Joined: May 2019
Posts: 3,197
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From: Mid-Atlantic
2025 C4 of the Year Finalist - Unmodified
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Best to find a body shop that specializes in Corvettes and knows what they're doing. There's one really close to me, but depending where you live your mileage may vary. It's the only way it's gonna get fixed correctly. My two cents.
