Actually, at 19 degrees the only heating issue was in traffic in hot 100 degree weather. My distributor is an FBO stage II, and Don set it up for 18 at idle. Motor is a 9:1 360 with a 455/475 Doug Herbert Cam.
Any other time of the year traffic was not an issue. I have the clutch fan going back on, just need to acquire the fan shroud.
Point being said what is your total timing....10 is my initial and 35 is my total in at 2900 rpm....too much initial timing will cause you issues also..remember that I see those hot temps also...
last night's pic with HHR fan and snow shovel air spoiler...