Running cooler than thermostat - Team Camaro Tech
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post #1 of 12 (permalink) Old Mar 19th, 18, 09:32 AM Thread Starter
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Running cooler than thermostat

At the dyno, the gentleman who dyno'd the engine suggested removing the bypass hose from the manifold to the water pump and drilling two small holes in the thermostat for circulation until its up to temp and opens the thermostat. I took his suggestion after running it by a trusted engine builder.
Long story short, I am running a 180 degree thermostat but only get to about 160 degrees.
Some more about the build:
Roughly 9.5 to 1 compression 427
Griffen exact fit BB radiator
Derale 18" rigid race fan. (sucks a ton of air)
I'm not running a heater so both water pump holes and manifold holes are capped off.
I believe I do want the car to run at 180... correct? It may run better a bit better with the aluminum heads at warmer temps... correct or was I given wrong advice?
Is this anything to be concerned about?
Thanks, Jim
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post #2 of 12 (permalink) Old Mar 19th, 18, 12:37 PM
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Re: Running cooler than thermostat

If your temp gauge is accurate then my guess is your stat is stuck open. With alum heads my Nova runs typically 10 degs cooler than the Camaro with iron heads. I believe I used a 160 stat in the Nova and a 180 in the Camaro.

For reference the Camaro stays about 180/185 and climbs to 190/195 under extreme duty or very hot days. The Nova runs 170 normally and under extreme conditions will climb to 180/185 max.

Your engine will make a bit more power running a bit hotter, newer cars run 210 by design. I think the 170-190 range is perfectly safe, and the only issue I see with 200-210 is under hood temps can start messing with fuel delivery on a carb'd engine.

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post #3 of 12 (permalink) Old Mar 19th, 18, 01:20 PM Thread Starter
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Re: Running cooler than thermostat

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Originally Posted by DjD View Post
If your temp gauge is accurate then my guess is your stat is stuck open. With alum heads my Nova runs typically 10 degs cooler than the Camaro with iron heads. I believe I used a 160 stat in the Nova and a 180 in the Camaro.

For reference the Camaro stays about 180/185 and climbs to 190/195 under extreme duty or very hot days. The Nova runs 170 normally and under extreme conditions will climb to 180/185 max.

Your engine will make a bit more power running a bit hotter, newer cars run 210 by design. I think the 170-190 range is perfectly safe, and the only issue I see with 200-210 is under hood temps can start messing with fuel delivery on a carb'd engine.
I don't believe the thermostat is stuck open due to the difference in temps of the inflow side vs the outflow side of the radiator.
At the moment I still have no hood on the car which could also aid in the cooling. I guess this question could have/should have waited until I was all back together.
Thanks though for the good info, Jim

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post #4 of 12 (permalink) Old Mar 19th, 18, 03:25 PM
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Re: Running cooler than thermostat

The engine temp when warmed to operating temp should always be or about the t-stat rating. If not the t-stat is not working. Maybe the drilled holes are letting too much coolant pass when closed
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post #5 of 12 (permalink) Old Mar 19th, 18, 07:41 PM
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Re: Running cooler than thermostat

I don't think you have to have a hood for a real good test of your cooling system. Disable the fan and run the engine in the garage and watch the gauge. Without airflow your engine should heat up easily to 180-200 stat open or closed. You should be able to tell when the stat opens and the fluid really flows also.

You can also do the same thing but block the front of the core and leave the fan running. This way you can take it a step further by only partially blocking the core for a better idea of what is going on. If your cooling system is over powering the amount of heat the engine is making you'll be able to see it this way. If this is indeed the problem maybe a clutch fan would help, it looks like a non-clutch blade fan in the picture.

...Dennis

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post #6 of 12 (permalink) Old Mar 19th, 18, 09:53 PM
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Re: Running cooler than thermostat

Replace the thermostat you drilled holes in. It's not supposed to have any.
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post #7 of 12 (permalink) Old Mar 19th, 18, 10:06 PM
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Re: Running cooler than thermostat

Either your gauge isn't correct or the thermostat is faulty. I also have an 1/8" hole in my thermostat and doesn't seem to affect the engine temp. The engine should run at 180 if the thermostat is working. If the cooling system is too great (never heard of that), the thermostat should stay closed until the engine temp reaches 180. What does it idle at if you leave it sit for 20 minutes or so?
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post #8 of 12 (permalink) Old Mar 20th, 18, 07:18 AM Thread Starter
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Re: Running cooler than thermostat

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Originally Posted by bill3337 View Post
Either your gauge isn't correct or the thermostat is faulty. I also have an 1/8" hole in my thermostat and doesn't seem to affect the engine temp. The engine should run at 180 if the thermostat is working. If the cooling system is too great (never heard of that), the thermostat should stay closed until the engine temp reaches 180. What does it idle at if you leave it sit for 20 minutes or so?
It's a mechanical gauge and appears to be working correctly. After shutting off the engine, the temp spikes to close to 210 and you can sometimes hear the thermostat start flowing. If I start the engine it quickly goes down again.
I drilled two approximately 1/8" holes in the thermostat. Maybe just one?
I haven't yet had it on the street for more than a trip around the block or two so I don't have a lot of data to report but as I have her running as I try to tune her, this is what I've found. I do know that she has been running way to rich but I think I may have solved that issue. Am I correct that leaning her out should increase the temps a bit? I'll test that on my next days off.
Thanks, Jim

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post #9 of 12 (permalink) Old Mar 21st, 18, 08:22 AM
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Re: Running cooler than thermostat

I had the same problem with my engine after installing a new aluminum radiator. It seemed to cool so efficiently that it hardly made it to 180 and most times was running at 160. I actually thought I had a 160 Tstat until I took it out and verified it was a 180. I installed a 195 and have been really happy, runs 190-195 all the time now. I did not have any holes drilled in the Tstat.
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post #10 of 12 (permalink) Old Mar 21st, 18, 08:41 AM Thread Starter
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Re: Running cooler than thermostat

Quote:
Originally Posted by made2cut View Post
I had the same problem with my engine after installing a new aluminum radiator. It seemed to cool so efficiently that it hardly made it to 180 and most times was running at 160. I actually thought I had a 160 Tstat until I took it out and verified it was a 180. I installed a 195 and have been really happy, runs 190-195 all the time now. I did not have any holes drilled in the Tstat.
Thanks,
I think my first course of action is to change thermostats and not drill it or maybe one smaller hole just for some flow since I am not using a bypass hose.
Thanks, Jim

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post #11 of 12 (permalink) Old Mar 21st, 18, 10:01 AM
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Re: Running cooler than thermostat

I run a 160 stat with one 1/8th hole and my temperature runs 170
I would rather have my engine running on the cool side as opposed to hot
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post #12 of 12 (permalink) Old Mar 21st, 18, 10:56 AM
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Re: Running cooler than thermostat

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Originally Posted by 4Speed67CamaroRS View Post
Thanks,
I think my first course of action is to change thermostats and not drill it or maybe one smaller hole just for some flow since I am not using a bypass hose.
Thanks, Jim
If you get a Robert Shaw stat it will have a single hole already drilled. I don't think it is an 1/8" though...

My friends shop has built hundreds of BBC's and always used the bypass hose. I realize the stat with a hole in it is said to do the same thing but I would think GM would have done away with it to save on production costs if another option was as effective...
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...Dennis

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