Discussion Forum - Northstar Chevelle Club

BLyke · 1K+ Club

350 SBC recommended thermostat temp ??

Lost in the 60s · President

"If it ain't broke, don't fix it".
I would leave it alone until you have run it in warmer temps to see if the rest of the cooling system keeps up. Is the fan mechanical, or electric ?
I, generally, run 180° thermostats, never 195°.

BLyke · 1K+ Club

It is a mechanical fan
looks like the manual says 195

more ambition than brains · 1K+ Club

Ignore the manual.
Agree on the 180 degree.

We were far more concerned about overheating in the White Elky and Biskwik,

more ambition than brains · 1K+ Club

p.s.

Will probably run 195 stst in LT41956 project, as that one will be computer controlled, have high-capacity cooling, electric fans.

Too cool may affect performance slightly, too hot could be catastrophic.

180 degrees will still be pretty toasty on a warmed up carbureted vehicle.
Concern about adequate passenger heating would be unusual in the summer use of our cars.

Don't pretend to be a mechanic, however, think I am being practical.
Even with a 180 stat, white elky runs hotter than I like.
Hate antifreeze spewing out the overflow.
We may still swap out the clutch fan to verify the current one is working properly.

Karl

Derek69SS · Founding Member

Karl, on your LT1 with reverse-flow cooling you can go colder on the Tstat because the heads are cooled before the block, so your oil temps will be higher. I'd run a 160 in that, and bypass the coolant line through the throttle-body also. Modern engines run hotter just to burn cleaner for emissions... stock LT1 fans don't turn on until I think 220 primary and 230 secondary. I hate to run them that hot.

Old Gen1 SBC I'd run 180.
Newer reverse-flow I'd run 160.

BLyke · 1K+ Club

thanks Guys

more ambition than brains · 1K+ Club

Thanks for the advice, makes sense.

Not trying to hijack post, however, sounds like we all agree on running the older stuff way cooler. 180 degrees makes sense.

I will definitely run the LT-4 per your suggestion.
1956LT4 project will have custom designed cooling and A/C module.

Thinking based on their limited use our cars leave a really small carbon footprint.

Karl

Enganeer · Mega Poster

180°F is a good balance for cast iron. I tried a 160°F T-stat on my 400sbc that has over 10.4:1 compression with iron heads (good dynamic compression ratio and tight quench) and reverse flow serpentine setup and it just ran too cold for a streetable temperament. Switched it up to a 180°F T-stat and it seemed very happy (counter intuitive at first for that much compression). Swapped out to a roller cam with less duration but more lift and got even better. Switching to Holley TBI helped even more as I could dial in fuel ratios, timing, knock sensors. electric fan controls, etc...

Don't forget to drill a small hole in the T-stat to help with to help bleed air out the system...the take away I hear it will run about 5 degrees cooler than rated.

Karl,

If you still running a stockish LT-4 and computer, don't be afraid to stick with around 190°-195°. Aluminum in general is so much better at heat transfer than cast iron to your oil/cooling system. You can play with lower temps T-stats but you may need to optimize the settings to realize the gains via a tuner. How much gain depends on your mods.

more ambition than brains · 1K+ Club

Good to hear from you John.
Hope all is well with you!
Karl

BLyke · 1K+ Club

"180°F is a good balance for cast iron. I tried a 160°F T-stat on my 400sbc that has over 10.4:1 compression with iron heads (good dynamic compression ratio and tight quench) and reverse flow serpentine setup and it just ran too cold for a streetable temperament. Switched it up to a 180°F T-stat and it seemed very happy (counter intuitive at first for that much compression)."

Thanks, this is a fairly mild 350 and think I will change it out, the Old Pontiac radiator seems to be pretty big compared to my 71 Chevelle