Extreme heat in 1974 Big Block

[Brian R.]

I recently purchased a '74 Big Block survivor (auto). My problem is the amt of heat that enters the passenger cabin through the shifter in the center console. I pulled the tranny and had it checked (it's OK). I also wrapped the exhaust which reduced the heat somewhat, but the CC still gets very hot. I live in southeast TX with temps running close to 100 in the summer. Help.

[Tom H.]

Re: Extreme heat in 1974 Big Block

Brian, From my experience as a former big block owner is that is pretty much normal. I'm sure someone will chime in with some ways to minimize the cabin heat. Im sure some additional tunnel insulation will be one of the suggestions.

[Russ S.]

Re: Extreme heat in 1974 Big Block

Tom is right. I have used a material that you can get at local auto parts stores that is about 1/8 inch thick,is a sticky backed tarish material with a foil on the top side. it is easy to conform to the floor and in areas that are too curved to conform you can just cut it and being it is sticky backed it can be butted up to the other cut edge and it will stay in place.

[Michael H.]

Re: Extreme heat in 1974 Big Block

I recently purchased a '74 Big Block survivor (auto). My problem is the amt of heat that enters the passenger cabin through the shifter in the center console. I pulled the tranny and had it checked (it's OK). I also wrapped the exhaust which reduced the heat somewhat, but the CC still gets very hot. I live in southeast TX with temps running close to 100 in the summer. Help.

[Brian R.]

Re: Extreme heat in 1974 Big Block

Thanks, guys. I was hoping for a miracle cure as summer is almost upon us in south Texas, but it appears that I'm stuck. I'll try add'l insulation, but my fear is that the heat may affect the tranny as well. I'm guessing that side pipes may be in my future.

[Bill C.]

Re: Extreme heat in 1974 Big Block

be sure the boot and seal are 100% around the shifter.

also - be sure the tunnel collar is in place. you should have installed it when the tranny was replaced.

there are a bunch of seals/plugs that are in the firewall - check those. Just becuase the heat seems to come from the shifter, it most definitely does not mean it not sneaking in from a half dozen other places.

if your car is an AC car, it can sneak in from the evaporator core box or from the bottom area where the heater hoses are connected.

otherwise - welcome to the normal heat a BB C3 throws off.

[Brian R.]

Re: Extreme heat in 1974 Big Block

Thanks, Bill. I'll double-check the seals. I have a '72 350 and am surprised at the heat the BB generates. Something I'll have to learn to live with.

[Joe L.]

Re: Extreme heat in 1974 Big Block

Michael------ Manual transmission 68-69 cars "sort of" used a double seal; automatic transmission cars used a single seal. All 1970+ cars used a single seal since the shifter boot for manual trans applications became leather and no longer represented any sort of seal. As a matter of fact, even 1968-69 cars really only have a single seal since if the lower seal is broken heat and fumes still enter the passenger compartment even if the upper boot is perfect. The lower seal is the critical one and, since these are unseen, these are very often ruptured. It's definitely the first place one wants to check if they're having heat or fume problems.

[Ralph S.]

Re: Extreme heat in 1974 Big Block

Put a manual water shut off valve in the 5/8 heater hose to stop the flow of coolant through heater core, it makes a big difference.!!!

[Joe L.]

Re: Extreme heat in 1974 Big Block

Put a manual water shut off valve in the 5/8 heater hose to stop the flow of coolant through heater core, it makes a big difference.!!!

Ralph------


Yes, that will help a lot, especially if the seals in the heater box are old and leaking (which, unless they've been rebuilt fairly recently, they will be grossly deteriorated).

[Brian R.]

Re: Extreme heat in 1974 Big Block

Thanks, Ralph. That's a great idea.

[Clem Z.]

Re: Extreme heat in 1974 Big Block

if the car has A/C there should be a water shut off valve somewhere. check to see if it is working. if there is no valve here is one that can be controled from inside the car. http://webcache.googleusercontent.co...www.google.com

[Terry M.]

Re: Extreme heat in 1974 Big Block

if the car has A/C there should be a water shut off valve somewhere. check to see if it is working. if there is no valve here is one that can be controled from inside the car. http://webcache.googleusercontent.co...www.google.com

Clem,
There should be, but Chevrolet didn't think so. I am not sure about 1974 that the OP asked about but not all Corvettes with C60 from 1968 to 1972 had a water shut off installed at St Louis.

[William C.]

Re: Extreme heat in 1974 Big Block

Another hint is to recalibrate the distributor back to the specs used on the late 60's bigblocks. They ran different timing and generally ran cooler as a result. The '74 models were just about the worst for emissions controls driving up temperatures.

[Brian R.]

Re: Extreme heat in 1974 Big Block

Thanks, Bill, I'll try that.