210+ at idle : (
Race Director
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Melting Slicks
Joined: Mar 2002
Posts: 2,164
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From: Beringen
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?
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?
Melting Slicks
Joined: Mar 2002
Posts: 2,164
Likes: 7
From: Beringen
Thread Starter
Instructor
Joined: Mar 2013
Posts: 145
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From: Athens AL
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.
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.
Thread Starter
Instructor
Joined: Mar 2013
Posts: 145
Likes: 13
From: Athens AL
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?
Melting Slicks
Joined: May 2009
Posts: 3,079
Likes: 315
2024 C3 of the Year Finalist - Unmodified
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.
Last edited by Faster Rat; Jun 24, 2013 at 04:22 PM.
Melting Slicks
Joined: Mar 2002
Posts: 2,164
Likes: 7
From: Beringen
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.
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.
Thread Starter
Instructor
Joined: Mar 2013
Posts: 145
Likes: 13
From: Athens AL
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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Le Mans Master
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From: RI, Now Franklin/Nashville TN
Instructor
Joined: Nov 2011
Posts: 234
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From: Warsaw Ohio
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.
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.
Racer
Joined: Apr 2005
Posts: 465
Likes: 1
From: FRANCE (Lyon)
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
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
Last edited by jerome1979; Jun 26, 2013 at 02:16 AM.
Thread Starter
Instructor
Joined: Mar 2013
Posts: 145
Likes: 13
From: Athens AL
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.
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.
Team Owner
Joined: Jul 1999
Posts: 65,492
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From: Orange Park Florida
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....
oh, BTW, my aftermarket cheepy gauge reads 10f too high, as proven by above instrumentation......so I just mentally knock 10f off the readings....
Thread Starter
Instructor
Joined: Mar 2013
Posts: 145
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From: Athens AL
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? : ]
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? : ]
Race Director
Joined: Sep 1999
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From: Plano TX
That sounds like a correct reading. Water enters the block and then goes up the heads and out the water neck. It warms up all along the way. Water temp should be higher at the water neck than in the head (where the gauge sender is).
Race Director
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Melting Slicks
Joined: Aug 2012
Posts: 3,487
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From: Titusville Florida
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.
Melting Slicks
Joined: Oct 2002
Posts: 2,317
Likes: 111
From: St Louis MO
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.
Thread Starter
Instructor
Joined: Mar 2013
Posts: 145
Likes: 13
From: Athens AL
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.
Melting Slicks
Joined: Aug 2012
Posts: 3,487
Likes: 83
From: Titusville Florida
I've done that and my 180 t stat opens just a hair above the first mark so it has a good deal of ways before it gets to the 200 mark.