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Originally Posted by Tin_Can_Terminator
(Post 1584234987)
There is some stuff that you can put in the Radiator that helps cool even more than normal Rad fluid. You can get it at Parts store.
TCT |
Originally Posted by marc9889
(Post 1584233855)
The problem child – 1972 C3 LS5 / 454 …. thanks in advance for the help.
The bad – High temperatures (hits 210+ with the A/C on) when idling. The good – Stays cool at highway speeds. 40mph or more, it cools down to 190 estimated, even in Alabama 90 degree heat. Not losing any coolant. What’s been done: - Radiator has been taken to a capable shop and cleaned / tested. - Expansion tank (aluminum) has been repaired (welded pin hole). - Radiator fan shroud seal kit and radiator support seal kit have been installed. - I’ve tried a 180 thermostat, a gutted thermostat (removed everything from the “ring” and even drilled holes in that), and no thermostat and it still gets climbs to 210 at idle. The 160 thermostat is currently in the car. - I drained the coolant and refilled with 80/20 water/antifreeze with Water Wetter. Still 210, but it seems to cool back down quicker at driving speeds. - The fan clutch seems to be working correctly. Even with the engine hot, I can turn the fan clutch by hand. - I replaced the water pump, which did not have an effect on the problem. - I used an infrared thermometer to verify the temperature at the water neck matched the gauge, and it’s within 10 degrees. - Several different timing setting have been tried, and based on the timing light and header temperatures, I think I have it set ideally. Equipment – Original A/C car, but currently running Vintage Air A/C, Aluminum expansion tank, original radiator (copper), 160 degree thermostat, RC-15 expansion tank cap, lower radiator hose has a factory looking metal tube (which cannot collapse), new water pump. Questions – - Did any 72 model big block cars come from the factory with an aluminum expansion tank? Mine has one. - With the aluminum expansion tank, does it need the RC-26 expansion tank cap or the RC-15 expansion tank cap? - What is the difference in the RC-15 and RC-26? - The carburetor (original) has two small vacuum ports, both pointing toward the front of the car. Did the car come from the factory with the vacuum advance attached to the port on the driver’s side of the carburetor or on the passenger’s side of the carburetor? I’ve tried both, but the car still gets hot. Attaching to the one on the driver’s side of the carburetor makes it run rougher, so I’m guessing it has more vacuum pressure. - Will the chin spoiler (or absence of it) affect cooling at idle? If so, why? |
Originally Posted by qwank
(Post 1584235175)
99% of new cars run at 210 degrees
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jb78L-82 - My apologies for misquoting you. I made an attempt at disambiguation, and made matters worse.
Belgian - I have tried all possible combinations of timing within the range that the car will run and not detonate, and the temperature stays at 210. Water Wetter - It was $18. If it helps, great. If not... it was $18. |
One of the questions that I was hoping to get an answer to - the carburetor (original) has two small vacuum ports, both pointing toward the front of the car. Did the car come from the factory with the vacuum advance attached to the port on the driver’s side of the carburetor or on the passenger’s side of the carburetor?
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Originally Posted by marc9889
(Post 1584235511)
One of the questions that I was hoping to get an answer to - the carburetor (original) has two small vacuum ports, both pointing toward the front of the car. Did the car come from the factory with the vacuum advance attached to the port on the driver’s side of the carburetor or on the passenger’s side of the carburetor?
Your engine will run cooler on manifold vacuum. I put mine back on ported vacuum after re-curving the distributor and installing a more appropriate vacuum canister for my engine. I am just trying to make the car the same as it left the factory...at least in appearance to the un-trained eye. |
Originally Posted by marc9889
(Post 1584235467)
jb78L-82 - My apologies for misquoting you. I made an attempt at disambiguation, and made matters worse.
Belgian - I have tried all possible combinations of timing within the range that the car will run and not detonate, and the temperature stays at 210. Water Wetter - It was $18. If it helps, great. If not... it was $18. |
Thanks Faster Rat (and everyone else). I browsed Doc Rebuilds site and found a document that shows the factory routing of the relevant vacuum lines. Since the spark control solenoid has been removed from my car, the vacuum line runs directly from the port on the front/drivers side of the carburetor to the vacuum advance. My plan is to cap the port on the carburetor and tap the manifold vacuum, which should eliminate any further need to mess with vacuum. Afterward, I’ll check the timing and change it if necessary.
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Originally Posted by qwank
(Post 1584235175)
99% of new cars run at 210 degrees
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Your problem is right here : "- The fan clutch seems to be working correctly. Even with the engine hot, I can turn the fan clutch by hand."
The best way to check for a defective fan Clutch is : get it good and warm 210 is great open the Hood then have Someone shut off the Engine while You observe the fan. It should stop turning almost immediatly after the Motor stops. At this temperature it should be locked up tight, if it keeps spinning replace the Fan Clutch. |
Try a Hayden clutch fan ref:2799
Use a 180F thermostat (160F is too low and won't cure any cooling issue) Check your radiator Plug (low pressure inside cooling circuit tend to running hot) This is probably already done but: Set your timing to have all in before 3000rpm. Try to have max advance without knock, so il will determine your idle advance timing for exemple: 34°@2800 HEI mechanical advance is 20° (20° is the norm but you need to be sure) so you need to set idle timint at 14° after this set your vaccum advance and plug it on Full vaccum port to help idle cooling hope this help Ps: My 350ci ZZ430 run 1st mark of temp gauge (approx 180F) all day long |
Originally Posted by 70LQ4
(Post 1584246936)
Your problem is right here : "- The fan clutch seems to be working correctly. Even with the engine hot, I can turn the fan clutch by hand."
The best way to check for a defective fan Clutch is : get it good and warm 210 is great open the Hood then have Someone shut off the Engine while You observe the fan. It should stop turning almost immediatly after the Motor stops. At this temperature it should be locked up tight, if it keeps spinning replace the Fan Clutch. |
:willy: I assume you have a good/calibrated IR heat probe, and have verified your temps.....a good thermocouple gauge like on my Fluke DVM works good also, but you have to heat sink it to the head for 100% accuracy.....I have both, and they agree on every test....so I"m cool with the IR gun I use.....
NOW, I have noted over the years that on thermostats of years past, they had different size openings, the 160 and 180 stats were larger diameter holes in the center, allowing more flow of course, when open that is, TODAY, and are all smaller openings like same as the 195f stats, so only the opening temp is affected, but overall flow is the same.... to get around that I drill 3-4 3/16 holes in the skirt of the stat, which is about as large as I can go without messing up the mounting or function.....this will make warm up a tad longer, and in really cold winters on the freeway I note that it runs about 150-160f but that's rather seldom driving for me.... :smash::yesnod: oh, BTW, my aftermarket cheepy gauge reads 10f too high, as proven by above instrumentation......so I just mentally knock 10f off the readings.... |
I have an infrared thermometer that reads 10 degrees higher than the gauge when I point it at the water neck. "Calibrated" ... not really. "Accurate"... I would say pretty close. I'm intentionally leaving the 160 thermostat in place until I see some temps come down, but it will definitely come out at the appropriate time.
I also drilled holes in my thermostat, as well as tested it with a gutted thermostat and no thermostat. All 3 approaches resulted in 210+ on the gauge and 220 on the infrared thermometer. So does it get cold enough in Orange Park to need the heat? : ] |
Originally Posted by marc9889
(Post 1584251485)
I have an infrared thermometer that reads 10 degrees higher than the gauge when I point it at the water neck.
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Originally Posted by marc9889
(Post 1584251040)
The fan clutch doesn't "spin" when I shut the engine off at 210, but I can definitely turn it by hand. Ironically, it's the only part in the cooling system I haven't replaced.
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can I ask a question about the temp gauge? Sorry don't want to hijack the thread but it does kinda go with it, anyway, what does the mark between 100* and 200* represent on a 76? I was thinking tha tit was 150* but from reading through this thread I'm rethinking that.
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Originally Posted by marc9889
(Post 1584243220)
Thanks Faster Rat (and everyone else). I browsed Doc Rebuilds site and found a document that shows the factory routing of the relevant vacuum lines. Since the spark control solenoid has been removed from my car, the vacuum line runs directly from the port on the front/drivers side of the carburetor to the vacuum advance. My plan is to cap the port on the carburetor and tap the manifold vacuum, which should eliminate any further need to mess with vacuum. Afterward, I’ll check the timing and change it if necessary.
To be sure, apply a vacuum gauge to each source and read the vacuum. Changing from ported to full manifold vacuum will instantly raise the rpm at idle which will then require a partial closing of the throttle with the curb idle speed set screw... The end result is a more efficient idle and lower idle temperatures. |
Originally Posted by AirborneSilva
(Post 1584251941)
can I ask a question about the temp gauge? Sorry don't want to hijack the thread but it does kinda go with it, anyway, what does the mark between 100* and 200* represent on a 76? I was thinking tha tit was 150* but from reading through this thread I'm rethinking that.
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Originally Posted by marc9889
(Post 1584255194)
I recommend letting the car's temperature come up to that mark and checking the engine temperature with an infrared thermometer. That way, you'll know the temp no matter what they intended.
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