Tom,

First of all 250* is not that hot for a .12 especialy durning breakin. If you have lots of smoke there is not too much to worry about. Some engines are just real tight and will get hot until broke in.

"HSN really wont effect an overly lean lsn @ idle , just try adjusting your lsn."

AI is right here!

During breakin the low speed responce should not be crisp at all, if so you are to lean on the bottom. If at 3 to 4 turns on the LSN it is too rich and loads up and or dies turn the idle screw in a bit until it stays running. If you are not driving the car and getting the RPM's up the HSN won't do anything for cooling.

What kind of temp gun are you using. Unless you are using one of the better ones (exergen, SP?) I have seen temps off as much as 40 to 50*. When I am breaking in a engine I will heat it up to about 250* with a heat gun before I even turn it over. After it is running I try to maintain temps between 230* & 240*. I do this by wraping the head with tin foil. This alows me to run very rich and still keeps the temps up.

Richen up the LSN!

If you have any more questions just Post up!

Scott