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FFCobra Fanatic
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1,065 Posts
Discussion Starter #1
I've seen several references to drilling a 1/8th inch hole in the top of the thermostat. What EXACTLY is the purpose and why don't manufacturer's put one in it??? Our car is running a bit hot and I thought I might try it. 351W w/ all Edelbrock components and a Holley 750.There may still be a small air bubble in the system. Thanx, Brian
 

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FFCobra Fanatic
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908 Posts
Sometime there can be a "bubble" of air trapped by the thermostat that a 1/8" hole will pass. Some of the thermostats have a simple check valve already built in. My Autozone brand one did. In either case you still have to make sure the hole/check valve is at the top. All that said, the hole just makes it a bit easier to get all the air out and the water flowing initially through the system. Once you have a good volumn of flow and fluid I'm not sure it helps all that much.
 

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FFCobra Craftsman
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22,743 Posts
It's just there to help til the t'stat opens.Most useful til the air is bled out of the system.Fairly useless after that.
 
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