Author Topic: Heat insulation - '71 BB  (Read 173 times)

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Offline Old guy

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Heat insulation - '71 BB
« on: January 12, 2020, 04:21:26 PM »
Hi, read a few articles on here about trying to keep the heat out. I've read on US vette sites about Reflectix. Here's a link to sellers on Amazon with various pics  about it https://www.amazon.com/Reflectix-BP24025-24-Inch-25-Feet-Insulation/dp/B0022NH3E4

It's multi layered and has a silver reflective product at either end.

Is there something here in Oz like this?



Offline Vettech

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Re: Heat insulation - '71 BB
« Reply #2 on: January 12, 2020, 04:44:25 PM »
You should have a layer of heat reflector, then underfelt, then carpet.

Thats from the "build book" for my 78. Alas Convertors seem hell bent to rip all this out, and your lucky if you get the old carpet plonked back up against the inside of the fire wall.

I purchased a roll of heat reflective sound deadner - looks like under felt with Silver Alli coating.

Cant remember where from, I can see the leftover roll but I cant physically get to it to see if it has any branding.

Its about 1/2" thick (10~13mm) Foil on one surface, approx 900/1000mm wide, I tried a few via samples - I'm pretty sure one even had a side which was preglued - ie peel and stick with a pressure senstive surface.

I would be carefull with polyethelene or similar plastic products, make sure first that all holes in the fire wall are sealed - I had 32 in the 78.
Even a 1/8" hole is like a thermal lance once the donk and manifold reaches temperature


Once the car has forward motion, the lower pressure in the cab (even with windows open) with literally SUCK the heated air into the cab.
 Once fire wall sealed, new heat/sound deadner, new carpet - it was like another car.

Another thing to watch if converted is manifold air escaping over the fire wall and into the plenum, then the heat/AC system will draw it in.
There should be a rubber seal which runs across the top of the fire wall thence forward down each side of the guards.

One of our club members drives his C3 with the hood up on the safety catch - this allowes hot air directly into the Plenum and also has the effect of reducing the  "Ground Effect", this is a partial low pressure created under the vehicle once forward motion of ~>50kph is reached, loss of this also destroys the vehicles road hugging and therefore handling. But each to their own.
Vettech.

Offline Old guy

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Re: Heat insulation - '71 BB
« Reply #3 on: January 12, 2020, 05:28:41 PM »
Cheers. I also noticed someone saying they put a valve in their heater line and close it. Holes, etc seem to be a culprit and that explanation regarding the pressure is great. Thanks

Offline Vettech

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Re: Heat insulation - '71 BB
« Reply #4 on: January 12, 2020, 05:46:29 PM »
Depending upon the year, the AC/Heater set ups differ,  most modern cars tell you they have climate controll, when in fact the water goes thru the heater matrix all the time and you mix the cold AC air with a little hot air for the desired temp. But modern cars have better insulation etc.

BUT - cutting off the hot water can help. But they usually cut off the forward flow, heat will still soak thru from the other direction, best fix is a heater matrix by-pass.
Vettech.