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My heads are ported and polished and decked 882 heads and water pump and thermostat are new I tested the thermostat in boiling water and it opened fully immediately. Cam specs intake duration @ 0.50 204 valve lift .420 lobe separation 107 exhaust duration @ .050 214 valve lift .443 love separation 117 the heads on the front both passenger and driver say 186 degrees and my upper and lower hoses are 162 degrees but my factory dash gauge says it's overheating. Do I ignore my gauge or is it actually overheating. I was using a factory fan with no clutch and stock shroud but I switched to dual electric fans with shroud and a 185 degree temperature sensor and no change with when it says it's overheating. Any help would be appreciated. I also have a AEM air fuel ratio gauge and it idles and light throttle at 14.52 full throttle at about 12 so I don't think it's running lean.
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I know the wiring is good it's says it's been overheating even before I rebuilt the motor but it never went but a couple needles past halfway unless it was sitting in traffic. And I have changed the sending unit twice before I rebuilt it with no change so I'm going to guess it's the gauge. I will look into getting a digital gauge to put next to my afr gauge.
 

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First thing is get a decent gauge on there. This can be mounted under the hood if you prefer not to contaminate a stock panel. I’d suggest a mechanical rather than electric to take senders, receivers, wiring and voltage out of the equation.

Bogie
 

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Based on your story problem I think it’s your gauge based on the following facts In your post.

1) in your 2nd post you say the gauge always said the engine was over heating, prior to rebuild.

2) your getting good temp readings at heads and hoses, this makes me think you have a laser temp gun to check temp.

3) you say you installed electric fan with a 185 sensor to turn on fan.What you don’t tell us does fan cycle on and off? If it where over 185 my guess is the fan would never shut off. If it never comes on then, your not getting up to 185.
 

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Discussion Starter · #7 ·
Based on your story problem I think it’s your gauge based on the following facts In your post.

1) in your 2nd post you say the gauge always said the engine was over heating, prior to rebuild.

2) your getting good temp readings at heads and hoses, this makes me think you have a laser temp gun to check temp.

3) you say you installed electric fan with a 185 sensor to turn on fan.What you don’t tell us does fan cycle on and off? If it where over 185 my guess is the fan would never shut off. If it never comes on then, your not getting up to 185.
The fans never turn off and yes I have a laser temp sensor. I also have two bottles of redline water wetter in the coolant mix and I am at 50/50 coolant water mixture. I had a 165 thermostat in the motor prior to rebuild and it would read over half to 3/4 temp. With the new 185 thermostat my upper radiator hose reads between 185 and 195 but the heads read between 205 to 215 degrees when the gauge says it in the hot range. I am going to use an AEM digital temp gauge so I can use a data logger for when I turbo the motor and run a boost controller and eventually use a Holley fuel injection setup. Was also thinking about using the thermostat housing with the two hoses to bring hot coolant from the back of the intake.
 

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I’d suggest a mechanical rather than electric to take senders, receivers, wiring and voltage out of the equation.
I'll second that recommendation. Also, a mechanical fan on a properly functioning fan clutch, with a preoperly matched fan shroud, will outperform many electric fan setups overall, and will outperform the ones in his picture even at idle.

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Any help would be appreciated. I also have a AEM air fuel ratio gauge and it idles and light throttle at 14.52 full throttle at about 12 so I don't think it's running lean. View attachment 626179
Several observations here:
  • You give lots of details about the temperatures (good, relevant), and the cam (slightly relevant, but you leave out some important information ...
  • Is this engine fuel injected or carbureted?
  • Does it have a conventional points/distributor ignition system? Or an electronic ignition system that uses a mechanical/vacuum operated advance mechanism on the distributor to adjust timing? Or does it have a fully electronic ignition where the computer adjusts timing without any mechanical movement in the dizzy?
  • You mentioned running a mechanical fan without a clutch. Did you have the matching fan shroud installed for that? Or were you running without the shroud as well?
  • The electric fans you're running now, are they marked on the motor something like "800W 12V"?
My first observation is that 210°F to 215°F at the head or at the thermostat outlet isn't really "overheating" for most engines. That's pretty much normal for most fuel injection systems. It's only a little high for a carbureted engine with a lower temp thermostat (160°F or 180°F).

Second, I've seen those electric fans before. A few times in person, and many other times on the internet. They are trouble. The fans themeslves barely pull 650 CFM each (1300 CFM total) through an actual radiator. That's just not adequate. And with that shroud, they actually draw as much or more air through the louvers when you're stopped than they do through the radiator. Twice I've taken those off Chevy trucks/SUVs and replaced them with the original mechanical fan/clutch/shroud and all the overheating issues the owners were having went away.

I've also replaced them on another LS swapped import where there wasn't room for a mechanical fan. On that one, I used a pair of Spal high performance fans on a new shroud that was mostly solid except for the fan openings and a few rectangular openings for Spal "flaps" that open at highway speeds and close and seal when the vehicle is stopped.

Your radiator looks like a Chevy truck (S series most likely, or maybe a Colorado or Trailblazer). If there's room for the original fan, clutch and shroud, use that. It's good enough for the entire warranty period on trucks that haul trailers (towing package), it's good enough for a mildly "hot rodded" V8.

BTW, your cam sounds like a Gen I "Vortec" cam. Is (or was) this a Vortec 5700 (L31) engine?
 

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Discussion Starter · #9 ·
I'll second that recommendation. Also, a mechanical fan on a properly functioning fan clutch, with a preoperly matched fan shroud, will outperform many electric fan setups overall, and will outperform the ones in his picture even at idle.


Several observations here:
  • You give lots of details about the temperatures (good, relevant), and the cam (slightly relevant, but you leave out some important information ...
  • Is this engine fuel injected or carbureted?
  • Does it have a conventional points/distributor ignition system? Or an electronic ignition system that uses a mechanical/vacuum operated advance mechanism on the distributor to adjust timing? Or does it have a fully electronic ignition where the computer adjusts timing without any mechanical movement in the dizzy?
  • You mentioned running a mechanical fan without a clutch. Did you have the matching fan shroud installed for that? Or were you running without the shroud as well?
  • The electric fans you're running now, are they marked on the motor something like "800W 12V"?
My first observation is that 210°F to 215°F at the head or at the thermostat outlet isn't really "overheating" for most engines. That's pretty much normal for most fuel injection systems. It's only a little high for a carbureted engine with a lower temp thermostat (160°F or 180°F).

Second, I've seen those electric fans before. A few times in person, and many other times on the internet. They are trouble. The fans themeslves barely pull 650 CFM each (1300 CFM total) through an actual radiator. That's just not adequate. And with that shroud, they actually draw as much or more air through the louvers when you're stopped than they do through the radiator. Twice I've taken those off Chevy trucks/SUVs and replaced them with the original mechanical fan/clutch/shroud and all the overheating issues the owners were having went away.

I've also replaced them on another LS swapped import where there wasn't room for a mechanical fan. On that one, I used a pair of Spal high performance fans on a new shroud that was mostly solid except for the fan openings and a few rectangular openings for Spal "flaps" that open at highway speeds and close and seal when the vehicle is stopped.

Your radiator looks like a Chevy truck (S series most likely, or maybe a Colorado or Trailblazer). If there's room for the original fan, clutch and shroud, use that. It's good enough for the entire warranty period on trucks that haul trailers (towing package), it's good enough for a mildly "hot rodded" V8.

BTW, your cam sounds like a Gen I "Vortec" cam. Is (or was) this a Vortec 5700 (L31) engine?
It gauge said was was beyond hot with the factory shroud and fan without a clutch it runs cooler with the electric fans the carburetor is a Holley 750 with mechanical secondaries the distributor is an accel with an accel super coil and cut to length accel wires the cam is for a gen 1 motor but more aggressive but not to radical the only inclination it's running hot is it's hard to start when it says it's overheating but it's always been that way and the truck has less than 80,000 miles on it since it was new. I have documentation left in the truck when I pulled it out of a junkyard and drove it home there was whole file of inspection paperwork going back 20 years and oil change receipts. It's always said it's overheating somewhat since I had it ten years ago. Never ran at 1/2 always at 3/4 on the gauge
 

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Add me to those who suspect the gauge or the gauge sender.

I'm assuming here that it isn't losing coolant and running with a half full radiator.

Oh, and for timing, are you using vacuum advance from the manifold? or ported vacuum from the carb? It will run cooler with manifold vacuum than it will with "ported" vacuum from the carb.

What do you have the base timing at? That's with the vacuum line pulled off the dizzy and plugged.
 

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My heads are ported and polished and decked 882 heads and water pump and thermostat are new I tested the thermostat in boiling water and it opened fully immediately. Cam specs intake duration @ 0.50 204 valve lift .420 lobe separation 107 exhaust duration @ .050 214 valve lift .443 love separation 117 the heads on the front both passenger and driver say 186 degrees and my upper and lower hoses are 162 degrees but my factory dash gauge says it's overheating. Do I ignore my gauge or is it actually overheating. I was using a factory fan with no clutch and stock shroud but I switched to dual electric fans with shroud and a 185 degree temperature sensor and no change with when it says it's overheating. Any help would be appreciated. I also have a AEM air fuel ratio gauge and it idles and light throttle at 14.52 full throttle at about 12 so I don't think it's running lean. View attachment 626179
 
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