[ZeGermanHam]

Sorry for the multiple new posts today... Questions are popping up for me as I reassemble the '66.

I have used 80mil butyl sound deadening (think Dynamat) throughout the entire inside of my car, including the interior firewall and upper cowl underneath the dash. I also have on hand but not yet installed the two fiberglass sections of underdash insulation that are glued to the upper inside of the cowl below the top of the dash.

Question: How necessary are these fiberglass pads? The butyl sound deadening I've already applied should help with noise suppression. Are the fiberglass pads vital for keeping engine heat out? I'm looking at these things on the desk next to me and thinking that I'd rather not install fiberglass pads in my car when they will invariably turn to dust which gets blown out through the HVAC system directly at me. The yellow fibrous side faces outward for Pete's sake...

[fyrffytr1]

It may be to help keep the heat coming through the windshield from harming the wiring and other parts under the dash. Why not use some Dynamat there as well. Extra insulation can't hurt.

[ZeGermanHam]

That's a good consideration as well. I'll take a look to see what kind of alternative material is out there. Like I said, I already have Dynamat type butyl sound deadening installed in that location, by my understanding is it is only for mitigating sound/vibration and not heat mitigation. So that means I'll have to find a foam type material I'd imagine. I only need a little bit, so hopefully I don't have to buy a $70+ box of whatever just to get what I need for this location.

[Cardo]

I would not use the fiberglass... It will eventually degrade and fall apart like the original, and the fiber fall out always makes a mess. I glued this stuff above my headliner to the roof and the bottom of the top of the dash. Worked well. https://www.speedwaymotors.com/Alumi...g_q=insulation

[Scarebird]

If you feel heat is an issue, I would run the flat version of that split black water pipe insulation. Won't degrade and offers the best R value.

[ZeGermanHam]

Originally Posted by Cardo

I would not use the fiberglass... It will eventually degrade and fall apart like the original, and the fiber fall out always makes a mess. I glued this stuff above my headliner to the roof and the bottom of the top of the dash. Worked well. https://www.speedwaymotors.com/Alumi...g_q=insulation

Thanks Cardo. And thanks for backing me up on wanting to avoid using the original style fiberglass. I can remember vividly how awful it was to work underneath the dash during disassembly. If I even slightly bumped a single wire, fibrous dust would come raining down on me. It was pretty miserable.

Originally Posted by Scarebird

If you feel heat is an issue, I would run the flat version of that split black water pipe insulation. Won't degrade and offers the best R value.

What do you think about this stuff: https://www.homedepot.com/p/Everbilt...0DRI/314983628

[Scarebird]

It looks like it should work fine; price is certainly good.

[ZeGermanHam]

I got my hands on some of it an hour ago. Probably going to put in 2-3 layers. Seems like it will work pretty well.

[ZeGermanHam]

Here is the end result after installing some heat insulation bought at Home Depot yesterday. It's typically used for insulating HVAC ducts, garage doors, etc. Super easy to work with. I folded it over on itself to make it double-thickness and attached it with 3M high-strength spray adhesive. Should work well I'm thinking, and this offers more full coverage than the original style fiberglass does.