Technical Tips > Pre 84
General help with my 72 Corvette Stingray
Vettech:
I would definitely check for holes in the fire wall. Mines RHD and had a total of 32 holes, even an 1/8th" hole lets in a virtual thermal lance of heat. Once the car has forward motion, a partial vacumm is created in the cabin which sucks in the red hot air which is straight off the manifold/exhaust. People used to say Corvettes are just hot, get used to it, "COS". In my experience, holes and the fact that the internal heat shield and other liners have been removed and not replaced are the cause. Good luck.
Oh! Remember that the air for the heater comes in via the plenum chamber at the top of the firewall. On 78's there is a rubber seal, which seals the hood to the top of the fire wall, if this is missing or is as hard as rock, then hot air will flow thru and up the windscreen, some will enter the plenum, thru heater matrix and your back to oven basting conditions. Also the internal, heat barrier, underfelt, carpet etc extend right up the inside of the fire wall, not just to the pedals. Great looking car !..
Scott:
--- Quote from: Speedvette on February 29, 2016, 10:19:22 AM --- Not sure whether I should just seal it over with a decent tape or drill 2 small holes and screw a bit of flat plastic over it for a permanent fix. The plastic will probably look like a more meant to be there fix.
--- End quote ---
Best option is to buy rubber grommets from the local rubber place that fit the existing holes. Like below, but the blanked off ones. Masters will stock them as well, but at much more $$$.
bfit:
mate there are a few hole in the fire wall that should have rubber plugs in them.
these are a tapered plug, you can find them on most of the suppliers in the US .
check the car to see if the trans tunnel insulation is still in place.
on a trip a good amount of heat will come from the transmission tunnel.
also make sure the heat shields are in place on the foot well engine side of both floor sections .
if they are there take them of and insulate behind them and refit.
Use something like Dynamat extreme on the inside of the car.
I found that a thermal heat shield on the fire wall engine side and under the floor between the floor and the exhaust cuts down a lot of the hear transfer into the cab.
when you are a little more familiar with the car pull the carpets and insulator the interior floor and firewall.
77CVT:
Heat shield on engine side is far more effective than shielding the cabin side. My 71 has metal "false floor" shields behind the exhaust which help.
These cars are great in winter - don't even need a heater! ;-) Plugging every little hole in the firewall helps.
Just get used to driving with the window down. :bolt:
On my old 77 I attached foam with foil backing and lined from the bottom of the firewall, under the floor to the back of the seat (attached with washers/rivets). Couldn't really see it and boy did it make an enormous difference.
bfit:
--- Quote from: 77CVT on February 29, 2016, 05:30:11 PM ---Heat shield on engine side is far more effective than shielding the cabin side. My 71 has metal "false floor" shields behind the exhaust which help.
--- End quote ---
Exactly
As I said re move the heat shield on the engine side of fire wall . Insulate behind them on the fire wall and refit shields .
I run a BB in a 70 modle headers and large exhaust . Every thing that's generates heat.
My car. Does not get hot even on a 40 deg day
Bfit
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