What is the correct thermostat temperrature for 351C

sgtjd

Well-known member
Joined
May 20, 2011
Messages
80
Reaction score
0
Location
Fairborn OH
My Car
1973 Mach 1
I rebuilt the heads last April and in the mean time I replaced a lot of other parts. In doing so I noticed a 195 degree thermostat in place. However when you read the shop manual for a 351C it takes a 180 degree thermostat. So I replaced the 195 with a 180. However, last summer was a hot one and occasionally I’ll take the 1973 Mach I in parades. What I noticed the temp gauge was getting hot and had readings in the 90% range. When I had the 195 in there I didn't have such a heat problem. All hoses and connections are new to include all new antifreeze. Water pump in good working order. My question is what would be the correct and safe thermostat temperature based on my situation 180 or 195?

 

Jeff73Mach1

VIP Members
Site Supporters
Joined
Apr 27, 2012
Messages
4,751
Reaction score
72
Location
Nashville, Tennessee
My Car
1973 Q code Mach 1
Generally speaking, once your engine exceeds the opening temperature for a thermostat, it will then run at whatever temperature the cooling system can manage unless the cooling system can maintain a lower temperature than the thermostat.

More simply, your cooling system doesn't care what temperature the thermostat opens at unless it opens at a temperature ABOVE the systems capabilities.

An engine should run above 195 for proper performance and below 220ish to prevent oil cooking

Did you use a cleveland specific thermostat (windsors use one that will "fit" but not seal to the restrictor plate underneath. . . is your restrictor plate in place?

Water cools better than anti freeze. Using a 50/50 mix of the two is pretty standard, but you can run more water in the summer to make your mix 75/25 and it will improve your cooling a bit.

If you need more cooling then look to a better shroud/ fan/ radiator (Preferably in that order)

Check your timing too. If you run your vacuum advance with ported vacuum change it over to unported and the advance at idle will usually reduce heat soak.

finally . . . your oil is also a huge component in cooling your engine. Consider adding an Oit temperature gauge and add an oil cooler if you need additional cooling.

 

hyena429

VIP Members
Joined
Apr 16, 2011
Messages
3,502
Reaction score
10
Location
wa
My Car
1973 mach 1
In the 190's range? I would not worry about heat at all unless it climed above 200 all the time....Mine was the same way...sticks around 180ish ...and on a very hot day around 100 degrees it mite clime a little above 200 in slow slow traffic...I seen the best of rigs in a 100 degree heat clime above 200...And i live in a very hot summer place...We get temps around 106 in middle summer..Hottest it has got here is 118....I was worried like you too..Cause i was in a hot rod slow cruze show...And i asked around anyone else motor runing hot? Im hitting little over 200 and worried a bit...They all laughed..they were all over 200 and more!!..lol

I dont think the 195 will let you run any cooler...Just hotter a bit over all.

 

Jeff73Mach1

VIP Members
Site Supporters
Joined
Apr 27, 2012
Messages
4,751
Reaction score
72
Location
Nashville, Tennessee
My Car
1973 Q code Mach 1
and factory gauges are like the pirate code, they are more of a suggestion.

They are rarely accurate. If you ain't pukin' coolant, you generally aren't overheating

 

sgtjd

Well-known member
Joined
May 20, 2011
Messages
80
Reaction score
0
Location
Fairborn OH
My Car
1973 Mach 1
Yes. My restrictor plate is in place I made sure of the that since its specific to my engine. Running 50/50 on antifreeze. It just seems that since I went to a 180 the gauge has really popped over to the hot side of the gauge. I may just transfer it back to a 195 since the gauge was more tuned to the middle and cooler side. What do you think?

Generally speaking, once your engine exceeds the opening temperature for a thermostat, it will then run at whatever temperature the cooling system can manage unless the cooling system can maintain a lower temperature than the thermostat.

More simply, your cooling system doesn't care what temperature the thermostat opens at unless it opens at a temperature ABOVE the systems capabilities.

An engine should run above 195 for proper performance and below 220ish to prevent oil cooking

Did you use a cleveland specific thermostat (windsors use one that will "fit" but not seal to the restrictor plate underneath. . . is your restrictor plate in place?

Water cools better than anti freeze. Using a 50/50 mix of the two is pretty standard, but you can run more water in the summer to make your mix 75/25 and it will improve your cooling a bit.

If you need more cooling then look to a better shroud/ fan/ radiator (Preferably in that order)

Check your timing too. If you run your vacuum advance with ported vacuum change it over to unported and the advance at idle will usually reduce heat soak.

finally . . . your oil is also a huge component in cooling your engine. Consider adding an Oit temperature gauge and add an oil cooler if you need additional cooling.


In the 190's range? I would not worry about heat at all unless it climed above 200 all the time....Mine was the same way...sticks around 180ish ...and on a very hot day around 100 degrees it mite clime a little above 200 in slow slow traffic...I seen the best of rigs in a 100 degree heat clime above 200...And i live in a very hot summer place...We get temps around 106 in middle summer..Hottest it has got here is 118....I was worried like you too..Cause i was in a hot rod slow cruze show...And i asked around anyone else motor runing hot? Im hitting little over 200 and worried a bit...They all laughed..they were all over 200 and more!!..lol

I dont think the 195 will let you run any cooler...Just hotter a bit over all.
the gauge when it was with a 195 was in the middle and lower. When I switched to the 180 it seemed to be way beyond the middle and even at the end on a 100 degree day.

 
Last edited by a moderator:

DaveK

Member
Joined
Jan 13, 2012
Messages
24
Reaction score
0
Location
Dousman Wisconsin
My Car
1972 Mach 1 Mustang with a 351C engine, FMX automatic transmission, ram air, blue exterior with argent stripes, black interior. Restoration project with my son.
I had my 351C completely redone with aluminum heads, high compression pistons and all the goodies. I also had the radiator recored to add capacity and added a high volume fan blade. I never even had a thermostat in the system until I started taking drives in the late fall. I had the oposite problem and could not keep enough heat in the system so I put a 180 in and the motor runs just fine even in the summer month when it is hot and just sitting there idling.

 

Jeff73Mach1

VIP Members
Site Supporters
Joined
Apr 27, 2012
Messages
4,751
Reaction score
72
Location
Nashville, Tennessee
My Car
1973 Q code Mach 1
I always test my thermostats with an infrared heat gun an a pot of water before installation. You might just have a bad thermostat. Also when wide open a thermostat still creates a bit of a restriction that may vary from brand to brand. The inrared heat gun can be used on the engine when fully warmed up to see some actual temperatures.

Check that your lower radiator hose isn't soft and collapsing

By all means try the 195 again, after testing it for function

 

BDK

Well-known member
Joined
Dec 31, 2011
Messages
191
Reaction score
0
Location
OH
My Car
1971 MACH 1
If your concerned with overheating why not use something like this: http://www.evanscooling.com/. It is a bit pricey but lasts the entire life of the engine, can be reused, reduces pressure in the system, non-corrosive and has an upper limit of (I believe) 350F......

BDK

 

sharpstang72

Well-known member
Joined
Apr 3, 2011
Messages
111
Reaction score
0
Location
MD
My Car
1972 Mustang Convertible
351C 2v, 4bbl,FMX, 9" Rear 3.50 gears
My car started puking antifreeze yesterday. The overflow (after market) bottle was full and the cap came off of it. In last three years, its never done that. I believe its the thermostat. Should I use 160℉ thermostat so it opens up faster and keeps the engine cool?

I also noticed some corrosion in the radiator, should I have it flushed? Any anti corrosive chemicals out there? Best method for flushing?

Any advice would be greatly appreciated.

 

marks73

VIP Members
Joined
Jul 19, 2011
Messages
4,829
Reaction score
13
Location
Pittsburgh, PA
My Car
1973 Mach 1 Q code 4 speed
1973 Chevelle 454 SS
2005 Magnum RT
2008 Colorado
No to 160. Yes to having it cleaned and flushed with a calcium lime scale remover.

 
Last edited by a moderator:

sharpstang72

Well-known member
Joined
Apr 3, 2011
Messages
111
Reaction score
0
Location
MD
My Car
1972 Mustang Convertible
351C 2v, 4bbl,FMX, 9" Rear 3.50 gears
How bout 180 marks73? Its recommended to use 195℉, but I want to keep it cool and opened at 180.

Let me know.

Thanks

 

wwhite72

VIP Members
Joined
Mar 9, 2013
Messages
997
Reaction score
2
Location
us
My Car
72 convert 351c
The correct robert shaw thermostat is actually 192 degrees. He thermostat only determines how long it takes your engine to come up to proper operating temperature. Warmer climates can use the 180 i suppose. As mentioned above, it doesnt affect cooling until it malfunctions. Then it can cause overheating immediately if it the type that fails in a closed position.

 

wwhite72

VIP Members
Joined
Mar 9, 2013
Messages
997
Reaction score
2
Location
us
My Car
72 convert 351c
You must be talking about a windsore

 

sharpstang72

Well-known member
Joined
Apr 3, 2011
Messages
111
Reaction score
0
Location
MD
My Car
1972 Mustang Convertible
351C 2v, 4bbl,FMX, 9" Rear 3.50 gears
I will go w/the 180℉. I have the chrome housing that requires not only the gasket but also the O ring. Should I just take the old O ring & match it up because I remember last timei replaced it I had a hard.time finding the same exact size. Also, is glue recommended?

Thanks

 

wwhite72

VIP Members
Joined
Mar 9, 2013
Messages
997
Reaction score
2
Location
us
My Car
72 convert 351c
I personally had bad luck with a chrome O-ring model. I dont recall if it was from ford racing or where i got it, but always leaked. I have had better luck wih one i got from Canton Racing and a plain gasket. You may have better luck than i did.

 

marks73

VIP Members
Joined
Jul 19, 2011
Messages
4,829
Reaction score
13
Location
Pittsburgh, PA
My Car
1973 Mach 1 Q code 4 speed
1973 Chevelle 454 SS
2005 Magnum RT
2008 Colorado
How bout 180 marks73? Its recommended to use 195℉, but I want to keep it cool and opened at 180.

Let me know.

Thanks
Where I live the engine compartment is almost 180 before starting the car! :p I use what the factory recommended for a number of reasons. When I was racing I didn't even use one. Just the proper size washer to keep me in the range.

 

Tubo

VIP Members
Joined
Jan 29, 2011
Messages
264
Reaction score
5
Location
Ft Walton Beach, Florida
My Car
1965 Mustang 2+2
1973 Mustang Convertable
n the 60's it was thought a 160 ish tmp was good gor the engine. By the time the 90's had rolled around, emissions research had revealed 190-195 is the better engine temp range to keep. Not only is emission control better, the engine actually suffers less bearing and piston ring wear, than at cooler 160 temps.

As mentioned, as long as you system is not boiling over(puking coolant) your not running too hot.

And on the "chromed" housing. Most ofter they are made from cheap pot metal, and will corrode through quickly. Necessitating early replacement. A little bit of bling isnt worth the added hassles. Replace that thermostat housing with a stock type in either aluminum or cast iron.

--------------------------------------------------------------------------------

 

matrixx

VIP Members
Joined
Jun 13, 2012
Messages
1,472
Reaction score
3
Location
virginia
My Car
1973 coupe
1998 mustang
1994 Nissan Sentra SE-R
On a cool day my cruising temp is around 165, if im in slow traffic or stopped idling for a bit it will creep up to 195 or 200. i get scared at 200 and this thread has eased my worries a bit. mines a windsor not a cleveland though.

 
Top