<VV> engine cooling

[shortle]

Is it possible for a Corvair to run "too cool"? After deflashing the 95HP cylinder heads, using a 12 plate oil cooler with both side shrouds, using the Otto Parts pan and valve covers, both of my rear doors barely start to open and then close again very quickly when driving. I know both doors move freely and both thermostats are operating properly.
Is it dangerous for an Corvair engine to be operating in low temps (0 degrees F to 40 F)? I have heard about starting an engine with cold temps. and valve seats coming out of heads.I am getting ready to take a (long) drive of about 600 
miles.Since losing an intake seat on my 140 PG Rampside I am now nervous.
Anyone?
Thank you,
Timothy Shortle in Durango Colorado.