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 What thermostat 160 or 180
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Two Feathers

26 Posts

Posted - 09 Feb 2016 :  10:20:59 PM  Show Profile  Reply with Quote
For the 461 alluminum head 10.75 to 1 cr...do i use a 160 or 180 im in california so its hot and traffic..clutch fan

The Great White Buffalo

7293 Posts

Posted - 09 Feb 2016 :  11:04:13 PM  Show Profile  Reply with Quote
I always use 160's and then if you need more heat in the engine just swap up.

Bowties are for Pee-wee Herman. LS swaps in Pontiacs should only apply to Fieros.
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Two Feathers

40 Posts

Posted - 18 Jan 2017 :  9:13:59 PM  Show Profile  Reply with Quote
Did I read That drilling a small hole in the thermostat flange will help stop air lock in the system ? just ordered a 160 stat and wonder if I should do this

What is the S, in Custom S ?
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Sitting Duck

1531 Posts

Posted - 19 Jan 2017 :  08:05:34 AM  Show Profile  Reply with Quote
I always do. It helps the block get the air pockets out when filling the cooling system,and there is no down side to it. I use an 1/8" drill bit.

I run a 160 degree in my GTO too BTW.

71' GTO Original 400 M20 3.23 posi
13.95@102.1 MPH on street tires

Edited by - 67drake on 19 Jan 2017 08:06:58 AM
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237 Posts

Posted - 19 Jan 2017 :  10:37:53 AM  Show Profile  Reply with Quote
I run a 160 in the 461 and the temp seems to stay in the 180 ballpark. That's with a cheap flex fan.

Robb Hermes
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Blued and Painted

3505 Posts

Posted - 19 Jan 2017 :  11:40:21 AM  Show Profile  Reply with Quote
Cooling and lubrication are closely related.
The viscosity of oil varies with its temperature. A 30 grade oil has a viscosity of 3 at 302F and thickens to 10 at 212F. It further thickens to a viscosity of 100 at 104?F and is too thick to measure at the freezing point of 32F.
The fuel system may like the cooler temps, but the engine oil needs to be near 212 for the least amount of engine ware.

Bull Nose Formula/ 461/ Q-Jet/
TH400/ 3.08 8.5 / R44TS.

Edited by - Blued and Painted on 19 Jan 2017 11:42:57 AM
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5448 Posts

Posted - 19 Jan 2017 :  12:24:25 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
I would prefer to run a lighter oil than run close to 210 all the time. I'd think heat kills more motors (and trans) than slightly too cool oil. But, i can see the worry, and i know modern cars love that 210 sweet spot for efficiency.
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Sitting Bull

139 Posts

Posted - 24 Jan 2018 :  4:15:20 PM  Show Profile  Reply with Quote
last summer I was using a 190 degree (195?) thermostat and the water temp gauge told me my car indeed would run at 195 degrees all day long, except when it didn't.

In the heat and especially in traffic it would creep above 210 and that bothered me.

Eventually I replaced it with a 180 degree "high performance" thermostat. Right at the same time the weather cooled off. Since then my car would cruise at 155 degrees and in the cold weather the heater could hardly keep me warm. That bothered me.

This past weekend I finally replaced my leaking and prematurely failed Flow Kooler water pump (that really bothered me) and also replaced my thermostat. Now I have a stock 180 thermostat. I am yet to drive it because it is raining ice up here in New Hampshire.

A side by side comparison showed that the 180 high performance thermostat has a much larger diameter hole and thus is a lesser flow restrictor than my stock thermostat. It's also possible that that particular unit was on the low side of the manufacturing variations and tended to open early. Hard to say.

I hope that my car cruises at 180, idles at 180, and provided lots of heat to keep me warm until June. I hope in the heat of July in traffic and cruising it remains well below 210.
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Sitting Bull

139 Posts

Posted - 05 Feb 2018 :  11:28:35 AM  Show Profile  Reply with Quote

I installed my new stock 180 degree thermostat and new Flow Kooler water pump and have driven about 200 miles since.

1. the Flow Kooler has an annoying feature that it leaks for about 100 miles before the seals "lap in." guys. figure it out. Ultimately not a problem since it has stopped leaking.

2. My 180 degree stock thermostat keeps my engine running at 190. WTF? sometimes is runs at 180. Usually it runs at 190. It's still winter up here in New England. What's going to happen in the summer?

3. MOST IMPORTANTLY. I NEED HELP. I have a new leak at the connection between the intake manifold and the water pump. WTH? This should not have happened. There are 500 pounds of iron keeping those two parts attached even when I remove the bolts to get the pump off. How do I seal this leak? Hose clamp and neoprene? If the two parts actually formed a long tube I could easily clamp it sealed but one abuts the other so I can't compress on the seal.

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Sitting Bull

178 Posts

Posted - 06 Feb 2018 :  3:20:01 PM  Show Profile  Visit Lee's Homepage  Reply with Quote
For the intake-to-housing interface, this is how I've had leak-free installations for the last 30 years.

1. Make sure both sealing areas are clean and free of paint.
2. Apply a light coating of Permatex UltraBlue (it sort of matches our engine color!) to the outer edge and sealing faces of the rubber doughnut/o-ring, then drop the intake into place.
3. Get all the intake bolts started, then thread down hand tight, but then back off about a half-turn. This allows the intake to be able to move fore/aft a bit.
4. Install the long cover-to-intake bolt, and tighten it down.
5. Tighten the other intake bolts.

CURRENT: '73 T/A clone, starting to get less boring!...
67 Firebird (sold) 11.27 @ 119.6 Feb. '05 issue HPP
69 Falcon wagon, 10.51 @ 130mph Feb. '10 issue PHR (sold)
72 Cutlass Convertible, first car, owned since '82, now with a 6.0 LS, mild, putting just under 400 hp/tq to the wheels.
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