War Machine

Thought about doing it when I get a garage.

Quote from the book:

"For summer operation we use a 160* thermostat and drill four .200" holes in the thermostat body. For winter operation we use a 185* thermostat and drill four .080" holesin it."

jackdaroofer

:cheers: I may be sticking my nosewhere it doesn't belong and therefore I apologize in advance

Drilling a hole in the thermo flange is generally done to eliminate any air that may be trapped in the cooling system when filling while the thermo is closed or filling with cool fluid.

Seems to me, and here is where I may be off base, but 4, 0.20 hole are the equivalent of almost one inch opening. This will virtually negate the movement of the thermostat valve. If you drill 4 holes that size, you might as well use the old Nascar deal and put a washer in place of the thermostat.

My experience has been, if you are trying to eliminate trapped air, drilling a very small hole, 1/16 or less.

If you are trying to use the thermo to somewhat restrict water flow to absorb maximum heat as the water flows through the block, use a washer, it's cheaper and requires less work. A washer with an opening about the size of a quarter ought to work fine

Again, maybe I missed something and therefore am out of line, sorry

PeteL

I think you are only a little out of line. :D

The point as you said is to allow air to escape. But also to allow some flow to pass the thermostat so it actually opens up at the right temperature. Stock thermostats allow some, a little more is OK and helps.

It will take longer to heat in the winter, which is not all that good. But it will allow quicker time to correct temperature if the rest of the cooling system is working.

Old wifes tale from long ago with restriction required in the cooling system. Faster flow is better for many, many reasons. But enough to say the with the side flow Corvette radiators and the pressure cap on the low side, restriction is not necessary and high flow is what you want.

Thermostat out is the most cooling you can get with the stock setup, but this works poorly for everyday use. High flow thermostat like some Robert Shaw models will do a lot, or you can drill holes. But all these mods will take a winter toll on engine life and performance.

Think a couple of small holes in a stock flange thermostat is a good mod, more will effect winter operation in a bad way.

Pete

93TorchRedC4

:confused: This is all news to me! I had no idea about this, but that's why I'm here, to learn from you guys. Thanks!!! :D

LWesthaver

I agree with your assesment. Many people don't seem to get the fact that the rate at which the water flows through the system makes little difference once above a minimal threshold. If the water is moving very fast through the system conventional wisdom says it won't spend enough time in the radiator to release the heat it carries. What most don't think about is that it won't spend as much time in the engine picking up the heat either.

Coolant is just a medium to carry heat from on place to another. As long as the radiator is adequate to remove heat faster than the engine produces it, it makes little difference what speed the cooling medium travels.

That's my story and I'm stickin' to it! :hat

bill mcdonald

To go one further, doesn't the tips book also say to plug the hole on the passeneger side of the block where the water pump goes along with this mod?

I dont have any idea what that does... Someone care to enlighten me?

jackdaroofer

:cheers: Thanks, I pride myself on usually being out in left field

But I do have to disagaree with a subsequent poster about high flow vs. low flow

True that time spent in the block absorbing heat and time spent in the Rad getting rid of it are important, but low and high flow aren't equal!

Nascar uses low flow with big exposed radiator area versus the block area. Time spent in the block vs. time spent in the RAD counts...I think :D

Anyway, nice to know I wasn't totally out of line :D

:seeya

LWesthaver

I suspect NASCAR has realized that a lot of energy is wasted pushing the coolant around the cooling system at high speed that could be better used powering the rear wheels. It makes more sense to move the coolant only as fast as need to convey the heat from the engine to the radiator. The large radiator is just an artifact of an engine that produces significantly more power than a street engine like ours.

CFI-EFI

BINGO!!!

Now HOW would you alter THAT, without changing the size of the radiator or the block(???)?

6 speed Sid

I always put one hole about 1/16 or so and it seems to work for me. Never tried 4 holes so I can't comment on the 4. Sid.

lead foot 85 vet

wait a min. one other use of the thermostat is to keep the heads and manifold full of water with back pressure and the nascar engines are turning 9000 to 10,000 rpm they don't need a fast turning pump. you can have a hot spot and crack a head taking that baby out. I'll vote small holes to let the air out. :smash:

PeteL

Then can I ask why the F you started this thread in the first place? :troll

PeteL

Wow.

89 Bob L

After speaking with alot of people, all agree that it is beneficial to drill a weep hole in the thermostat. Only one is needed, approx 1/16 to 1/8 of an inch. It does not effect the temperature in the summer or winter. It allows air to exit, making it easier to burp the system. More than one hole is overkill.

War Machine

:yesnod: Thank you for the correction! :cheers:

"The water pump bypass on a small block Chevy is located on the right water pump boss just below the water pump bolt. We plug it with some RTV and drill some holes in the thermostat to provide bypass circulation. For summer operation we use a 160* thermostat and drill four .200" holes in the thermostat body. For winter operation we use a 185* thermostat and drill four .080" holesin it."

This does not work for LT engines due to the different thermostat design.

TonyR2822

Jack actually knows why its done!! He is right . If you let the coolant flow to fast thru the radiator it will not have enough time to get rid of the heat and you will run hotter! 1\16 is more than enough. and no more than 2. Plus the cooler your engine runs the dirtier the emissions. You might not pass them than. Just put in a 180 and leave it alone :boxing

jackdaroofer

:D Thanks :D

drive it

Also (on a L98) if you plug the water pump bypass and install a high flow water pump-then drill those holes in a standard thermostat.....it'll run hotter! (been there, done that) I found I had so much press. that it was attempting to force the thermo to close. The solution was a high flow "balanced" thermostat....about $10.00 from Summit.
Just my $.02 to maybe save someone else from scratchin' their head for awhile....

NoWorries

I did it to relieve Cold Water Surge, no reason other than that.

War Machine

This has gotten some good feedback. TPIS is a supporting vendor. I'd love to hear why they ran cooler with this mod and everyone else runs hotter. Anyone from TPIS care to clarify?