I have a 53 merc with a 87 5.0 in it & it has been rebuilt.I am using the
original headers that came with the car (87 linc lsc) the floors get
so very hot.I have wrapped the exhaust pipes from the headers down
to the mufflers (not the headers) & i put a heat shield over the mufflers
and the floors still get REAL HOT my wife's feet are so hot that she cant
stand it,it just gets to hot inside.BTW my 53 merc is a convertible.
I sure hope that someone can help me. Thanks Bob

 

My neighbor has a 1955 Chevy with a blown 454 in it. With the car being black, having no A/C and the engine putting out major heat you can usually drive it for about 20 minutes before it gets so hot in the car that you literally cant stand it anymore and will be sweating like crazy.

A few weeks ago he bought some of this stuff and put a few coats on the floor and firewall and it has made a huge difference. I am sure there are other manufacturers selling a similar product that you can use.

 

I don't know for a fact, but I think from what I'm reading that IMHO you are trying to solve your problem from the wrong direction.
First wrapping the exhaust is just holding the heat in longer and allowing the pipes to get hotter and radiate more heat into the car. Are you using the cat converter from the donor? Those things get hot enough to set grass on fire.
Second, have you tucked the exhaust up nice and snug to the undercarriage in between the frame rails, so it can't be seen and gives extra ground clearance so you could lower or bag the car? If so that took the pipes out of the airstream so the heat doesn't have anywhere to go.
Third you said you installed a heat shield? What did you make it out of and how did you install it? is there any airflow between it and the floor? An effective heat shield would be 1/16- 1/8" aluminum sheet as large as possible installed with minimal number of spacers to give at least 2" of clearance between it and the floor and the frame and at least 2" of space between it and the exhaust pipes. It should NOT be tight against the floor or the pipes and it should extend forwards to the firewall or slightly further forwards of it to scoop air between it and the floor. Bias the space to give the most space possible between the shield and floor but give plenty of room for air movement around it. Curve or bend the sides down to shape it like an inverted tanning reflector.
Air space and air flow are your friends when heat dissipation is your goal. Fourth make sure you have some sort of heat barrier product on the floor and firewall inside the passenger compartment, the thicker and the more air space within the product the better.
Fifth install a bypass valve on the heater core and turn on the fan and/or open the fresh air vents, but be sure it has an outside air source that is as cool as possible. Didn't your Merc have fresh air ducts from the front of the car up under the fenders? Be realistic in your expectations, slow cruising local streets or the mall parking lot or parking with the engine running so you can listen to the exhaust or sound system on a hot and humid day/night in a felt poodle skirt and it's going to get hot inside.

 

I absolutely hate vendors that won't tell you the cost up front.

 

AX, Thanks for all the info on my heat problem.When i wrapped my pipes i did not realize
that i was trapping in so much heat,the floors were so hot before so i figured what do i have to lose. I am not using a cat & the car is not fuel injected,my exhaust system has room between the pipes & the floor.The heat shield was made out of aluminum & it was
at least 2in above the mufflers,the heat shield was only as long as the mufflers.I am going to get rid of that wrap that is on the pipes & get some insulation on the floor &
firewall. Thanks again Ax Bob

 

Ceramic Coating

I just thought of something. What about ceramic coating your exhaust?. Theres a local shop up here that does it and it doesnt cost much at all.

Heres a quote from there website "Measured decreases of 350°F in radiant temperature are average but protection has been found to be up to 500°F depending on operating conditions and design."

Sounds like less heat would radiate off of your exhaust and into the cab floor after it is ceramic coated. Like I said the cost of ceramic coating is pretty cheap up here and worth a shot.

 

That's because it ~ 75.00 a gallon + about the same for the special spray gun.

 

I have used the lizard skin and it is worth the money.

 

I didn't mean to say anything negative. I have no personal experience with it, but from what I have read it indeed does work, and these days 75.00 a gallon is not that extravagant for specialty paints and coatings.
They probably don't want to sell directly, but they should make it more obvious and easier to find a dealer and see the pricing that's all.

 

Ceramic coating works well but, for it to be effective it has to be applied to the inside of the pipe, not the outside and I don't think it can be applied to the inside of a muffler unless it's done during the manufacturing process.