74 Engine heat
Thread Starter
Instructor
Joined: May 2020
Posts: 116
Likes: 10
From: NC
74 Engine heat
Hello! So, its getting hotter out(for like 3 months now, but my windows are not operational yet so I just have too)
Well anyway, it gets really hot at the floorboard. I have been told that its the vents being stuck open, but after some light research I've learned it could be multiple things causing this - all in the same family luckily.
What is the most likely culprit? Which should I fix/check first? I am learning as I go.. So could we start with the easiest(Less hard) stuff first?
Well anyway, it gets really hot at the floorboard. I have been told that its the vents being stuck open, but after some light research I've learned it could be multiple things causing this - all in the same family luckily.
What is the most likely culprit? Which should I fix/check first? I am learning as I go.. So could we start with the easiest(Less hard) stuff first?
Burning Brakes
Joined: Jun 2010
Posts: 1,165
Likes: 93
From: Bellmore NY
MANY threads on this subject. There used to be posts form a guy named vettefixr, but they all seem to be gone. I posted some of the relevant info in this thread.
https://www.corvetteforum.com/forums...nder-dash.html
https://www.corvetteforum.com/forums...nder-dash.html
1967 Pedal Car Champion
Joined: Mar 2020
Posts: 9,205
Likes: 4,295
From: US-PNW
Hello! So, its getting hotter out(for like 3 months now, but my windows are not operational yet so I just have too)
Well anyway, it gets really hot at the floorboard. I have been told that its the vents being stuck open, but after some light research I've learned it could be multiple things causing this - all in the same family luckily.
What is the most likely culprit? Which should I fix/check first? I am learning as I go.. So could we start with the easiest(Less hard) stuff first?
Well anyway, it gets really hot at the floorboard. I have been told that its the vents being stuck open, but after some light research I've learned it could be multiple things causing this - all in the same family luckily.
What is the most likely culprit? Which should I fix/check first? I am learning as I go.. So could we start with the easiest(Less hard) stuff first?
The problem with these cars is that both the transmission and initial engine exhaust run within 3-6" or so of the floor and trans tunnel wall. All that heat is easily radiated to the fiberglass and into the passenger compartment. GM had a few solutions that may be missing or deteriorated in your car 45 years after being built.
- There should be a fiberglass and foil insulation liner that fits the transmission tunnel on the trans side of the tunnel.
- There should be a soft foam "horse collar" type of seal that fits over the trans bell housing near the engine mount flange.
- There should be jute padding under the carpet that runs completely over the entire floor and transmission hump.
- All/most/some years have two heat shields bolted to the firewall opposite the occupants' feet placement.
Thread Starter
Instructor
Joined: May 2020
Posts: 116
Likes: 10
From: NC
Dave and Derek and 67
MANY threads on this subject. There used to be posts form a guy named vettefixr, but they all seem to be gone. I posted some of the relevant info in this thread.
https://www.corvetteforum.com/forums...nder-dash.html
https://www.corvetteforum.com/forums...nder-dash.html
thank you! I’ll get a valve to cut off the water, then I’ll start knocking out that list.
Team Owner
Joined: Jul 2004
Posts: 40,435
Likes: 793
From: Redondo Beach, California
The 68's and I think hte 69's have a nice fiberglass blanket that fits under neath the floor pans and upartially up the firewall. The parts are still available at some of the Corvette vendors. Got mine from Paragon. Don''t know why GM didn't keep using them on subsequent years. Flat metal shields are included to prevent the fiberglass blankets from road damage.
Also the stock factory 69 sidepipes do a great job of lowering cabin temps. The exhaust pipes in the standard location go right along the transmission. At one point the left exhaust pipe is only a few inches from you gas pedal foot...only an inch or so of insulation protects your foot. The 69 factory sidepipe system will fit any C3 as far as I know. The factory sidepipes: PRO: they look great and reduce cabin temps. CON: they are now very expensive, they are noisier, and require filling the exhaust cutout holes in the rear valance panel to look factory,
Also the stock factory 69 sidepipes do a great job of lowering cabin temps. The exhaust pipes in the standard location go right along the transmission. At one point the left exhaust pipe is only a few inches from you gas pedal foot...only an inch or so of insulation protects your foot. The 69 factory sidepipe system will fit any C3 as far as I know. The factory sidepipes: PRO: they look great and reduce cabin temps. CON: they are now very expensive, they are noisier, and require filling the exhaust cutout holes in the rear valance panel to look factory,
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,172
From: Hermosa
If your running stock timing and port timing that will make the exhaust much hotter. A performance timing tune using manifold vacuum via Lars's papers will lower your exhaust temps thereby lowering your floor panel heat.
