I've owned a '70 LS-5 auto non A/C car all stock in the past. A sweat box in nice weather. Now have '72 L-48 converted to LS-5 auto, all GM still a bitch as far as comfort. like being in an oven. What was GM thinking? These cars are a joke as to drivers. ALLWAYS run hot even with all correct air dams,fan shrouds,seals, timing etc. I've seen many posts as to advance timing this, electric fans that, but still loads of problems. Bottom line TOO HOT!! By far the best driver was my base '72 L-48 4 sp roadster. Those that speak of pulling that non #'s 350 for a 454 or 427 I would offer a word of caution!
Opinions welcome. BB's are cool I guess but you WILL cook/bake or at the very least continually struggle to keep the temp down.

SW

 

How hot?

 

My 68 427 car isnt that bad. Sure, a long 70+mph(3.70 gears) run uphill will send the temp into the 210-230 range but I attribute that to the 20+ year old radiator in it, when it starts leaking I'll pony up for the DeWitts radiator and I'm confident that problem will be gone.

As far as interior heat goes, When I got it it was pretty bad but when I replaced the carpet I sealed up all the holes in the firewall and that made a noticeable difference. What made the biggest difference was replacing the hood seal, mine was totally missing and was dumping heat into the ventilation plenum at the base of the windshield and then at my feet. Now its pretty good, not new car good but definitely acceptable. Of course, its a convertible which I'm sure makes a big difference.

 

"Pretty good" and "acceptable" are among the terms other forum members have used in their futile ongoing struggle to keep the INTERIOR less than too hot. Even with my engine temp at 190-200 one continues to bake while driving. I have owned 5 C-3's '70-'72's BY FAR the best drivers were the non-A/C SB's as far as interior comfort. It is not so much the engine temp as the feeling you are in an oven while driving. This with all seals and air dams correct/stock and in good shape. Non A/C cars have much better outside fresh air coming into the interior as well . BB's with A/C are silly hot with very poor outside air flow. I would not want one as a driver/cruiser. A show car to draw ooh's and wow's perhaps, but as a fun,COMFORTABLE ride, it's SB non-A/C for me for sure.
SW

 

Can you tell if the heat is coming from the heater core area?
I checked mine with a IF gun lowered pass side 30 degrees by shutting off water to heater core. 1/2" ball valve shut off. L48 air/auto

 

Great tip as both of my BB's '70 and a '72 with '73 block all GM really had no need for a heater at all. General heat under both sides in floor area. Where did you put the ball valve?

thanks,
SW

 

1. What temperature thermostat are you using?
2. Are you using a wide mouth thermostat? http://www.summitracing.com/parts/mrg-4363
2. What is your initial timing?
3. Is you vacuum advance connected to manifold vacuum.
4. Have you tried an aftermarket water pump such as FlowKooler.

 

Everything is all GM and correct for '72 LS-5. New radiator/all shrouds and air dams in place /rebuilt correct carb.braided steel wires. Full tune up next,which AC Delco plugs would I use ?. My '70 LS-5 non A/C,auto,had none of these problems even being a 62K mile survivor when I owned it. A/C in an automatic BB C-3 is ridiculous HOT as to comfort.

Many thanks for the tip! I'll press or should I say BAKE on...

SW

 

The plugs would be R44T

 

I'm not having any problems. I just took a 210 mile ride through Sturgis in my 69 big block 496. The ambient temp in Sturgis was 95 degrees, the Vintage air kept me quite cool, and the car never hit 200 degrees even sitting in traffic. I have a 2 row aluminum radiator with electric fans and am running the supposedly inferior (for cooling) Evans coolant.

 

Out of everything that Ive done to try to control interior heat, the addition of hooker side pipes has by far been the biggest aid in reducing heat. Also the biggest aid in increasing fun factor.

 

Woodlawn
I put the ball valve out of sight, 1/2 way down to the heater core, then removed the handle & put it in the rear glove box that way I can turn the heat on this time of year her in Ohio
I can take a pic if you like?
Chuck

 

If your running a 160 thermostat, or none,it will not allow the water to cool by passing to fast through the radiator....the fluids just keep getting hotter. It may sound strange to bench racers but a radiator is to cool the fluids done by the stats operational temperature....actually a 1968 BB car as new required a 195...However I would recommend...a 180

Fancy high dollar water pumps are a waste of money. The OE pump is the best for a BB

 

The coolant spends the same amount of time in the radiator regardless of speed.(50%) If it's in the radiator longer to cool, it's in the heads heating up longer.

 

Yeah, the "too fast" coolant myth just won't go away. Look, if the coolant travels twice as fast it is in the radiator twice as often.

 

My 69 427 is nice to drive in, I think the 69s are cooler because they have
the insulation under the floor and up on the firewall, other year BB don't have that.
as far as engine temp 190-210, Northern IL does not get that hot though.

 

Thanks, A picture would be great when you get a chance.

SW

 

My L-48 auto with AC in it's stock form was a bit hot as well. The stock recirc fan has anemic flow and needs to be replaced with a C4 circulation fan. That mad a big difference in the interior temp by getting more cool air into the cabin.

The stock jute and carpet is insufficient to keep the heat out, as well as the noise. I use Fat mat Mega mat on the floor for noise and refexit on top of that then put the stock jute and carpet back down. Huge difference in interior noise and heat.

Side pipes definitely eliminated a source of heat from the floor pan, just as important was the ceramic coating on the headers which helps to keep the heat in the pipe and going out the exhaust for lower under hood temps.
If I had stock exhaust running out the back I would have heat shields under the floor on the outside to prevent heat from migrating into the cabin.
Also the ball valve on the heater core is a biggie. Two ball valves actually, one on each hose. The heat still gets to the core via conduction if only one is used.

Timing is set at 19* initial. Stock I was at 15* or so. Much less heat in the exhaust pipe this way.

As it stands now I am a little perplexed by the many people that have modded their cars to try to control the heat and have met with little success.
Maybe I have just got lucky but I have had great success thus far. So cold now that when I drive with the wife that she has to cycle the AC off because it gets too cold in the cabin. This is with 134A converted AC no changes in the condenser, hoses, or R4 AC compressor.

 

Thanks for the input as any info helps. My '72 loaded A/C auto coupe was a L-48. Pulled original 350 carb to pan and garaged at 80K Found a '73 BB original and installed. BIG mistake! Always fighting heat problems. would NEVER do it again. I've owned 5 C-3's in the past. BY FAR the best driver was the SB, NON A/C 4sp. A/C cars don't have the fresh air vents coming into the interior. '70 LS-6 auto non A/C., '70 L-46 4sp non A/C. '72 LT-1 coupe , '72 L48 roadster 4sp non A/C and the current "pizza oven", '72 L-48 loaded coupe converted to LS-5 ALL GM.

SW

 

Pull the carpet and lay in heat insulation, like dynamat, or lizard skin.

You can also wrap the exhaust pipes under the floors.