Flathead running cold

rhphotord

rhphotord

Senior Member
Ran the engine in my AV8 build for over an hour yesterday at various rpm's trying to replicate what I think was vapor lock. No luck with that but...Temp guage never got above 160 degrees.Not an especially warm day(62degrees) here yesterday and not complaining because it's not over heating but some explanation would be appreciated. Engine runs "cranky" when cold but bearable.
New rebuilt 42 flattie, Edelbrock heads,Edmunds intake with dual 94's, new aluminum radiator,new coolant, not running thermosats.
Run thermostats or do I leave well enough alone? Not wanting to fix something that isn't broken.
 
rhphotord said:
Ran the engine in my AV8 build for over an hour yesterday at various rpm's trying to replicate what I think was vapor lock. No luck with that but...Temp guage never got above 160 degrees.Not an especially warm day(62degrees) here yesterday and not complaining because it's not over heating but some explanation would be appreciated. Engine runs "cranky" when cold but bearable.
New rebuilt 42 flattie, Edelbrock heads,Edmunds intake with dual 94's, new aluminum radiator,new coolant, not running thermosats.
Run thermostats or do I leave well enough alone? Not wanting to fix something that isn't broken.
Click to expand...

No engine should be ran without the proper thermostats...
Running it cold will hurt it in multiple ways...performance, slush buildup...
If an engine overheats thermostats if not broken aren´t the reason for it...
 
Remove the thermostats and throw in some non-detergent oil!:eek: That's the way to treat a flathead!:rolleyes:

Where do these notions come from?
 
Last edited:
Its been a while since I got my rebuilt pumps back from Skip but IIRC he recommends running without thermostats or using Bob Shewman stats. But then again I could be mistaken.
 
tubman said:
Remove the thermostats and throw in some non-detergent oil!:eek: That's the way to treat a flathead!:rolleyes:

Where do these notions come from?
Click to expand...

They come from ignorance; from choosing to accept erroneous opinions. But I can't understand why! Maybe it's a matter of attitude, as in "My mind is made up. Don't confuse me with the facts!"
 
rhphotord said:
Ran the engine in my AV8 build for over an hour yesterday at various rpm's trying to replicate what I think was vapor lock. No luck with that but...Temp guage never got above 160 degrees.Not an especially warm day(62degrees) here yesterday and not complaining because it's not over heating but some explanation would be appreciated. Engine runs "cranky" when cold but bearable.
New rebuilt 42 flattie, Edelbrock heads,Edmunds intake with dual 94's, new aluminum radiator,new coolant, not running thermosats.
Run thermostats or do I leave well enough alone? Not wanting to fix something that isn't broken.
Click to expand...



Not running any stats at this point and the temps held around 160 with what you did so far is not a good feel for what you might expect driving in outside temps more near 70 to 80 degrees. I bet when once you drive in warmer temps you will find the actual engine temps to be more in the 180 range which is good overall. In my opinion the fact the engine runs cranky has nothing to do with the 160 temp its more a matter of getting the tune up a bit better. Since I have tuned more flatheads than most getting the dual 94s happy will be the fun part of your learning curve. Not running thermostats may produce a problem but theres a lot of factors to be concerned with one very important one is the aluminum radiator. I say keep running the way you have things now and see what the running temps look like when the outside temps get higher. If you need to control the coolant flow in the radiator I would start off with 160 stats. Remember if you go with the 180 stats theres usually only one way left for the temps to go and thats up.
Ronnieroadster
 
:Ronnieroadster" - Let me get this straight; you are recommending running non-detergent oil and no thermostats in a freshly rebuilt street flathead?
 
Going through a flathead learning curve here and I'm no young guy. Never stop learning and doing lots of listening and reading by those wiser than me. So I really appreciate all the feedback.
Think I have the carbs figured out after changing internal jetting etc. and adding a hotter ignition system. Have to put the car under driving conditions to better assess temp readings. In the end of the day maybe I do thermosats just not looking forward to coolant drain as it's a pain!
 
FWIW I use 74 degree C thermostats as used in early minis. 82 or 88 are also available but I use the 74s.

74C = 165F
82C = 180F
88C = 190F

Mart.
 
I'm not sure why you would want to run 160 deg thermostats or no thermostats. The hotter an engine runs the better it is for the engine and the engine oil. Not sure any automotive engine left the factor without thermostats. It the earlier days antifreeze mixtures did not hold up well at higher temperatures so the factor recommended operating temperatures were lower. This quickly changed over time and higher temperatures were recommended and pressurized systems used. Engines preform better at higher temperatures, as is evident will all modern vehicles. This is not practical with a flathead because of the radiators used and heat within the engine compartment. But I would try to run the engine in at least the 185 degree range. Thermostats help bring the engine up to operating temperature quicker and maintain a minimum temperature.
 
Last edited:
I would absolutely run 180* stats. That's what I've been running in my engine for 25 years and with a stock radiator.
 
rhphotord said:
Going through a flathead learning curve here and I'm no young guy. Never stop learning and doing lots of listening and reading by those wiser than me. So I really appreciate all the feedback.
Think I have the carbs figured out after changing internal jetting etc. and adding a hotter ignition system. Have to put the car under driving conditions to better assess temp readings. In the end of the day maybe I do thermosats just not looking forward to coolant drain as it's a pain!
Click to expand...




Your on the right path good idea to get on the road and see how things heat up. Then you can determine what you need to do. ;)
 
then on the other hand, I need math lessons in which I never got more than a D in math
60yrs ago. My car 46 my only ride new engine with 165 stats. Ok cardboard front of
radiator last September it is now almost middle of May still have cardboard boots gloves
Hoodie . Sept to May equals 8 months counting with my fingers; so whats left out of
12 months in a year, and I do not live in Alaska. I don't care about the cardboard and
wimpy heat, but its the coat, boots, gloves, long johns getting to me and the heat, house and shop still on $$$ When a kid melting in bed, no fan but the sound of bugs
lightning bugs= can't remember. The trade off is no bugs snakes spiders & bees.
just my rant LOL
 
If you have stats in and the car still runs on the cool side they are probably turned a bit sideways in the radiator hose and letting water flow past them. A Fordbarn and Regional Group member made a jig to drill 2 holes in the stats and 2 smaller holes to tap for 4-40 stainless screws to hold the stats to the water outlet on OEM center outlet (37-48) heads and aftermarket aluminum ones. It is a better solution then using wire or multiple hose clamps to make sure they stay where they should and don't have water bypassing.
 
I live in Alaska, I run 180 t stats in the heads (59A style) on my 8BA. As you know it’s hard to keep the modern t stats in place. Every time one of them turns out of place, I know it. Upon start up the temp on the side that turns takes a long time to warm up. I have dual gauges, and can see what it does. 15/20 minutes drive and left side is 190, right side is 160.
I’ve just got to come up with a sure fire way to keep them from turning.(yes I tried the wire) I’m thinking of welding them inside a thin tube, then slipping them inside the hoses.
 
Are your gauges reading correctly? Purchase an infrared temperature gun see if it matches the gauge reading.
 
You must log in or register to reply here.
Back
Top