No one thing made my 77 cooler, it was a combo of things that now make it so cold that it is a meat locker in the cabin if I want it to be.

Most pronounced was the removal of the original exhaust system. The heat under the passenger seat that radiated into the cabin was amazingly hot.
Second was putting in reflex insulation under all the carpet glued down with 3M spray adhesive. Cheap at Home Depot.
Don't forget about radiant heat from other sources like the windows. I tinted all the windows except the windshield to the darkest allowed by law.
Also the T-top covers radiate lots of heat from the heating of the sun. I insulated those under the removable interior panel. Big difference in a black vette.

The blower fan needs to be upgraded to the C4 blower fan. A/C was cold but not circulating very well. Cold air is denser and harder to move the original C3 blower was not up to the task.

Shut off valves for the heater core. Unless you are in max A/C, hot water is constantly circulated through the heater core making it pretty hot in the passenger foot well. This is assuming the stock vacuum actuated valve is working properly. If it's broken you get hot water in the heater core regardless of A/C selection.

also consider upgrading to electric fans. The A/C condenser likes all the air possible flowing through it for cooling. Stock fans respond with engine RPM. So at idle you get significantly less air through the condenser and your A/C warms up at idle. Electric fans run all out all the time if needed. This keeps air flowing through the condenser at a good rate making A/C cooler at idle.

Ceramic coated headers. This keeps the heat in the exhaust better as it moves to the end of the pipe, keeping under hood temps down.

These things and the others listed make a big difference. Like I said a meat locker. Even at 100* F.

 

On my '76 the cat is directly under the pax seat and there is a metal shield above it which I presume was put there to keep heat out of the cabin. Did your '77 have this set up?

 

Yes. I removed the heat shield when I put on the side pipes. I guess it kept the seat from melting.

 

Yep, that cat can put out some heat. Thanx...

 

Take a look at the overall design of the original (only if original) 1982, including exhaust routing, cat location, dual fans, etc. as a guide. I can't speak for all '82's, especially in the hotter southern/western States - but, even on the longest drives, at any highway or stop& go speed-bands, on the hottest (100+) days and longest drives my stock/still all original car does not generate any uncomfortable heat from anywhere. I've put my hand on the carpet, especially the passenger side looking for signs of heating and it is just not there. When I replace my carpet this Spring I am going to install Hush mat and Reflectix because many members of our forum here have raved about the quieting effect, but unrelated to heat. So, study the '82 design for clues, perhaps?
My question to you, has anyone installed floor insulation and regretted it for any reason. Some have complained of an industrial rubber smell, but just wondering if there are any other good reasons to give it s second thought before installing hushmat?

 

Thanks for the info guys!

I actually have done a ton of researching and got samples of the 4 major mat brands.
Hushmat, dynamat, fatmat, RaamMat BXT. For the thickness, feel, and cost, RaamMat BXT WAYYY surpasses the others...and is a great deal!
PM me for any questions/sizing/thickness.

I have decided to finish the project then decide if I will need to install any "mat" b/c I do not have a baseline yet. I have a 454 with 550 HP, CONVERT, Sidepipes...AND never cruise with windows up/top on (dont really fit)...so not sure how much it will help me. But will need a baseline first.

Will be doing the heat barriers for sure.

THANKS!

 

AS mentioned. ALL firewall plugs, grommets and under hood seal help greatly

I have done numerous Corvettes with a two layer product that goes on the firewall and all the way back to the rear seat mounting bolts EVERY square inch possible. SERIOUS temperature drop.

And the most recent Corvette I have done is a 74 coupe with A/c...and when he is driving it...as he has told me...the temp out of the center vent is 42 degrees (on a modified MAX-A/C set-up)....and he can sell ice cream out of it in the summer. And when he feels down by the side of the shift console...he feels absolutely no heat.

DUB

 

place car in a dark garage, place a bright spot light under the engine bay/motor.
then look from inside the cabin at the light coming thru.
mine looked like a disco ball with all the missing grommets/holes.
main ones were where the carpet plugs that hole the carpet up under the pedals were susposed to be

 

Thanks guys!!!

Awesome info!

R