Hey guys, I was able to get my hands on a 1974 Corvette last spring and took it out quite a bit in the summer. Only problem is, the interior gets hot enough to cook an egg. So I've decided to attempt to remedy the issue. I took all the old carpeting out and found what looks like a previous attempt to insulate it with some sort of spray on goop. With some chemical stripper I was able to get some off using a putty knife, however, if I'm looking to spray on something like Lizard skin, do I need it all gone or just the thickest areas? If I leave some on should I spray primer over everything before putting down the insulation?

Here's a picture of the interior currently. The red is the old insulation and the dark spots are where I've been able to get it down to the fiberglass.

Thanks!

 

As far as insulating the cabin, using a spray product that turn into a solid will only reflect heat until it itself gets hot, then will radiate heat. Good for sound deadening. There are kits sold that are reflective heat shield. Also check the trans insulation. Look to see if there are any holes in firewall that are open allowing heat in, you'll be surprised at the number you'll find. Wrapping you're exhaust system helps to reduce heat. This is a well covered problem with our cars and maybe some others will chime in with their solutions. T

 

Do some searching on the forum here there are many posts about this heat issue.

Not sure what the red product is but it might have been something like lizard skin to help with insulation and I would leave it there while adding something else over it. If the coating is partially helping why remove it because it would only help your new efforts more than taking it off.

Very best thing is a heat shield on the outside done with the engine and trans out. Otherwise there are other things to do including inside hear shielding like being sure the heater core hoses both have valves preventing the core from heating up, blocking holes from the engine bay, etc..

Before doing anything else do a deep search of heat in the cabin of the C3 because it has all been done before.



EDIT: Looking at the picture. Is the engine and transmission out? If so don't overlook the killer solution to the heat problem by installing an outside heat shield to the bottom of the car and be sure to install the heat collar over the transmission.

 

C3's were fairly quiet and interiors did not get particularly warm when they were new. The factory placed pieces of 1/2" thick jute padding in strategic locations to minimize heat entry, and used pieces of tar-sturated cardboard for sound deadening material (dampened high frequency road noise). Both were very inexpensive and both did a reasonably good job. The downside of the jute material is that after many years and probably being soaked with water/beer/etc. several times, the jute material gets compacted and no longer has the many air pockets in it needed to perform gppd heat rejection.

But, if kept dry, jute can do a good job for many years. I think some of the vendors are now procuring a foil backed jute material that is pre-cut for easy installation. Any foil backing should be on the floor side of the installed insulation so that it reflects radiant heat FIRST.

You do not need heat insulation in the storage compartment area...unless you installed twin turbos under there. But, noise reduction material is a MUST in that area.

Specifically, you need to verify that the rubber boot around the shift lever does not have any cracks/tears/holes that would allow HOT air from entering the cockpit. You also need to COMPLETELY cover the trans tunnel area and the inside of the firewall with heat insulation.

There are other specific heat-entry issues that need to be inspected/resolved. You can find them by doing info SEARCH on reducing cockpit heat.