Thermostat range

[bkahler]

In my eclectic collection of parts I only managed to find one NOS thermostat of the correct style for my truck. I tested it in a boiling water and it works fine but it starts to open at about 155 degrees and is full open around 162 degrees. That leads me to believe its a 160 degree thermostat.

The manual says to use a 180 degree thermostat. Living in central Arkansas it gets darned hot here in the summer and only into the 20s for short periods in the winter. I'm inclined to try using this thermostat first to see how well the truck runs with it.

Any comments or suggestions

Thanks,

Brad

[52B3B108]

If I remember correctly, my stat only opens to about 160 or so. I've wondered too whether to put in a 180.

[Guest Nile Limbaugh]

Years ago 160 was standard for those engines but 180 was an option for winter. I've always used the 160 with no problems.

[Reg Evans]

Ditto.

[grey beard]

It is likely the 160 degree thermostats hark back to alcohol antifreeze days, for that was the norm then. Today, with ethylene glycol coolant, I like to run a minimum of 180, in order to get the block warmed up more quickly on short runs. This has the additional benefit of helping to keep the engine cleaner, if you are still using the old road draft tube crankcas ventilation system.

Using modern antifreeze, even with no pressure cap, your boiling point will be closer to 250 then to 212 degrees, so a 180 stat feels about right to me. JMHO:)

[Don Coatney]

NAPA sells a new 180 degree thermostat that works on an external by-pass system for less than ten bucks. Part number THM155. There is a thread about this on the P-15 side.

[Reg Evans]

Don,

A few questions about your redheaded fire spitter....Have you installed it yet?

How much did you have milled off?

Did you do a compression check before and after the install?

How can you determine if the head has been milled in the past?

Just curious if and how much your compression reading increased and if you could feel an increase in HP.

The reason for all these questions is because I have a Spitfire head ready to install on my truck but now I'm thinking I should have had more than .050 removed.

[grey beard]

Gents,

Methinks the question is not how much the compression will go up - actually it's the compression RATIO we wanna' raise, not the cranking compression.

When I was ready to do my cylinder head, I put a wad of solder on top of the piston dome and cranked the engine over a few times with two head bolts holding it on. Did the same thing on top of both an intake and an exhaust valve after they were adjusted, and based on the space available above these parts I took an even 0.100" off. She cranks nicely and sounds real healthy. Could have taken more off, but I really don't know how much meat there is in the head water jacket area left to play with. After all, head gasket thickness can vary nearly that much depending on composition and different brand names.

Anyhow, why be greedy? JMHO

[Don Coatney]

.

Have you installed it yet?

No.

How much did you have milled off?

Thirty thousands. Did this based on my measurements of my reground cam total lift. I dont want any valve to head clearance issues and left room to remove more meat in the future.

Did you do a compression check before and after the install?

When installation day arrives I will do this. Compression checks on my engine have always been 120 # across the board.

How can you determine if the head has been milled in the past?

James Douglas bought a NOS head. He sent me the measurements before he installed it. My Spitfire head measured the same as his NOS head.

Gents,

Methinks the question is not how much the compression will go up - actually it's the compression RATIO we wanna' raise, not the cranking compression.

Dave;

Cold cranking compression readings are a good indication of compression ratio in a healthy engine.

[IanT_Qld]

Using modern antifreeze, even with no pressure cap, your boiling point will be closer to 250 then to 212 degrees, so a 180 stat feels about right to me. JMHO:)

Well what do ya Know! I've learnt that 212F is boiling point. (only ever use Degrees Celsius) When I replaced my thermostat I took the housing to the shop and chose a thermostat that would fit, and would open between 175 and 212 because according to my temp gauge that is operating temperature, settled for 180F as that felt right. I am off the belief that the sooner the block get to temp the better.

Air temp is generally between 15 and 38 C max air temp (60-100F) where my truck is kept in Queensland.