Head Temperature

[Die Hard]

What is considered too high for head temperature on a Twin Cam? At what temperature do you risk engine damage?

[Pirsch Fire Wagon]

Very interesting question.

That is a question perhaps can't be answered specifically. Numerous factors affect critical temperature. Oil, Ambient, Saturation, Bearings, Oiling Jets, etc. I would think the list of components causing the failure would be extensive.

I assume someone could, in a controlled environment conduct a destructive survey. Oil Temperature Average is 220* - 260* and Head Temps run 300* - 350*.

I would be persuaded to lean to the critical viscosity breakdown of a given oil thereby failing to lubricate.

When I teardown I can witness excessive heat but, have no definite reference of what temperature caused the damage.

[838]

What is considered too high for head temperature on a Twin Cam? At what temperature do you risk engine damage?

How are you measuring this? What temps are you seeing? My 117" will see highs of  290-295  on really hot days measured by power vision. 11.25:1 compression and 210 ccp.

[Die Hard]

My head temp sender is on the the rear of the front head just to the left of the intake manifold.

I am not using an oil temp gauge because the sending unit for it on the Screaming Eagle plus 1.5 quart oil pan is at an awkward location behind the primary and simply sticks out to far for my comfort level. Besides that, I would like to think head temp is a more pertinent reading than oil temp.

[Appowner]

Where on the head the temp is sampled is also important.  Especially should you compare different engines.  An IR image of the head will show different temps in various parts of the head with the exhaust valve area being the hottest.  Consistency is key here.  I suspect the temp difference between the intake and exhaust manifolds could be 100 degrees or more.

[Die Hard]

I have S&S Super Stock heads and they came with the head temp sender location already machined out in the location I described above.