One other thing I thought of. Since your car is a 74 I know for sure that the A/C equipped cars came with a heater control valve operated by vacuum. I'm not sure if the non A/C equipped cars came with a heater control valve or not. If it is not opening or not opening all of the way that could be the problem. That would sure keep things from warming up. You could have a bad heater control valve, vacuum line from the vacuum switch in the controls in the car or the vacuum switch on the control could be bad. The vacuum switch also controls the doors in the heater-A/C unit in the car. The heater control valve is mounted on the passenger side fender well. If you touch the heater hoses going into coming from the heater core both should be hot with the car warmed up and at operating temperature. They will both be about the same temperature. Just be careful they get hot.

One thing you could do to test things is remove the heater control valve and just splice the two halves of the heater hose together. Fill it back up with anti-freeze and water then warm the car up and see if you have warmness in the car.

The heater control valve as far as I know controls the temperature of the heater and also shuts off the flow of water when you are not using the heater. I've seen them go bad for no reason. I had one once that created a vacuum leak for me that drove me crazy trying to find it.

_________________
Former bent 6 owner
Mark

Well, there y'go, it's a defective thermostat! Unless I'm in a really big hurry, I always try to pan-test a new thermostat before installing it. Push the valve plate open, insert a piece of string, let the valve snap shut, hang the stat in a pan of water so it's not touching the bottom or sides, and put the pan on the stove. Use a kitchen thermometer to measure the water temp constantly and note when the stat drops off the string. If your stat is opening at 135-140, your engine will never warm up, regardless of what kind of fan you have.

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

Yep, factory-A/C equipped cars had heater control valves. '63-up A-bodies without A/C don't have heater control valves. Starting in '71, the heater control valve is a single-acting item, spring-loaded into the open position. Vacuum closes it when "MAX A/C" is selected; otherwise it's open (unless, of course, it is clogged!)

But, it sounds like his engine is running too cold, not just his heater.

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

My gas gauge reads over full when full and is pretty accurate. Let me know how the voltage limiter circuit goes. If it helps or not. The bottom line is that the inside heater core doesn't put out that much heat in the winter and that is just recycling cabin heat, no outside air.

No A/C on my car.

I guess you can hijack your own thread.

Thanks!

_________________
Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Ok, guys I can't believe I got three bad Stant stats in a row. I have been buying Stants top of the line stainless steel units. However, the next on that goes in I will try the string trick in the boiling water.

By the way, this condition was happening before and after changing heater cores three time now, radiators three times, thermostats three times, senders three times and heater hoses three times. It was allot of work and I am beginning to think that the water jacket on my motor is just too big since it runs so cool.

No A/C and I run the heater water lines on top of the block to keep them warm. If you want to see a picture, PM me.

Thanks..

_________________
Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Motor simply has to create heat, no way around it. Water pump pushing water ok? Is the system getting up to pressure? What about the lower hose--it's not collapsing under pressure?

"Water jacket too big", "radiator too efficient", etc. are just not realistic explanations for what's going on. Something is the matter with your cooling system and/or heater system. I agree it's unlikely you got three bad Stant stats in a row. It sounds like you're not certain whether your engine is running too cool or if it's just that your heater isn't working well enough, so the first thing to do is to loosen the radiator cap to the first stop (no pressure) drive the car for 15 minutes or so, then with the engine idling remove the radiator cap and use an accurate kitchen thermometer to check the temperature of the coolant in the top tank.

There are various ways the heater can fail to produce useful amounts of heat, even if the engine coolant is in fact reaching normal operating temperature, so let's first figure out of that is the case.

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

Ok, I bought a nice meat/candy thermometer and did the test. It reads 155 to 160 degrees max.

What is the next step?

_________________
Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG