Author Topic: General help with my 72 Corvette Stingray  (Read 13300 times)

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Offline Speedvette

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General help with my 72 Corvette Stingray
« on: February 28, 2016, 11:20:40 PM »
Hi all,

I bought my first Corvette Stingray about 1 week ago. All original matching numbers 72 Corvette Stingray which is a pleasure to drive.





I have a few little things I want to fix but need some advice on these issues. It seems like the heater is always on around my feet. I have noticed the vent box above my feet drivers side which is beside the steering column has a hole in it, the hole being about the size of a 10 cent piece, looks like it's meant to be there. Has had some tape over it at some stage. Is this hole supposed to be there? If it is I guess I just may have to plug it somehow.

Also there is a tap handle on the heater line in the engine bay. As I understand it, its supposed to have some sort of electric valve but instead has the manual valve. I checked it tonight and it was in the closed position, so I dont think this is the reason for the hot air coming out of the vent.

Lastly I have a PCV valve that has 2 outlets on the top of it. I need to get a new one as sometimes this one get a little noisy. Where could I get one like this?

Cheers

Offline metalhead

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Re: General help with my 72 Corvette Stingray
« Reply #1 on: February 29, 2016, 08:51:24 AM »
Welcome! I'm no expert, but I'm sure if I get something wrong I'll be corrected! Firstly, these cars are known for bad heat soak into the footwells. If it didn't have aircon then the heater core did not originally have any way of turning it off to my knowledge, so the tap is a useful addition. Check for unplugged holes in the firewall (dark garage and someone shining a torch from the engine bay is a good way to start). I believe there are some holes that were originally for carpet plugs that are often open. I have my heater core bypassed at the moment (leaking) and it still feels like the heater is cranked in the footwell, so this is on my list too!

Not sure about the pcv or the hole in the vent you're referring to, sorry, but I'm sure someone else will be able to help out.

Great looking car!

Offline sirfixalot

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Re: General help with my 72 Corvette Stingray
« Reply #2 on: February 29, 2016, 08:54:40 AM »
Is hole on R/hand side of column above the accelerator pedal? Car being LHD the heater box is on R/hand side of car.The main reason for hot air coming into cabin is holes in firewall.Park the car in a dark garage & put a bright light in engine bay then look in car under dash for light bleeding thru.Don't know why the PCV would be making a noise

Offline Scott

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Re: General help with my 72 Corvette Stingray
« Reply #3 on: February 29, 2016, 09:02:21 AM »
As said, lots of heat comes through the holes in the firewall.  The tap on the heater line will be an add-on by someone trying to cool the interior down.  On mine, the water runs through the heater core all the time and the flaps in the heater box keep the heat out, in theory.  In realty most the seals in the heater are had it and let in lots of heat.  Half way down the page there are some pics of my heater box.  It's an air-con one so may be a little different.

http://nswcorvettes.com.au/forum/index.php/topic,6964.72.html

Offline Speedvette

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Re: General help with my 72 Corvette Stingray
« Reply #4 on: February 29, 2016, 10:19:22 AM »
Thanks guys. I'll check for any firewall leaks and fill those in as best I can. The car has recently had a new heater core installed also but as I said the valve was in the closed position.

The hole in the heater box is to the right of the column ( LHD Car), I'll try and get a pic up for you guys. It definitely feels like most of the heat is coming from this hole. 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.

As for the PCV I'll just see if I can get something similar from the local auto parts shop.

I'll add more little issues as time goes on.

Cheers.

Online Vettech

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Re: General help with my 72 Corvette Stingray
« Reply #5 on: February 29, 2016, 12:06:27 PM »
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 !..
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Offline Scott

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Re: General help with my 72 Corvette Stingray
« Reply #6 on: February 29, 2016, 12:17:45 PM »
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.

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 $$$. 


Offline Bfit

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Re: General help with my 72 Corvette Stingray
« Reply #7 on: February 29, 2016, 01:04:51 PM »
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.
 
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Offline 77CVT

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Re: General help with my 72 Corvette Stingray
« Reply #8 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.

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. 

Offline Bfit

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Re: General help with my 72 Corvette Stingray
« Reply #9 on: February 29, 2016, 06:00:19 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. 

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
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Offline Speedvette

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Re: General help with my 72 Corvette Stingray
« Reply #10 on: March 01, 2016, 12:24:37 AM »
Cheers guys. I've got some time this weekend so i'll fix these firewall holes then.

I need to get my front seats recovered. My interior code is 412. Looked at what EcklersCorvette sells in the U.S and it seems they only have Medium Blue original seat covers for a 72. Also looked at Corvette America's website and they only have a Royal blue for a 72. Which one would I be after? If anyone has the blue interior in a 72 I'd appreciate some help in making the right choice the first time. :thumb:

PCV is fixed too. Turned out to be a Ford PCV  :lol:

Here's a photo of the hole in the drivers side vent box just to the right of the steering column. It almost looks like to me that the box has come apart, what do you guys think?



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Re: General help with my 72 Corvette Stingray
« Reply #11 on: March 01, 2016, 11:02:37 AM »
Experience with early ford/comadore tells me that is a join, and the hole looks to be moulded, some just have a hole like that to give air to the feet. The long join would have a spongy tape on one side, when pushed together forms a seal, or they use duct tape to seal and support.
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