I have an aluminum block with B1 heads and set the valves exactly as you stated. My hot settings are supposed to be 22In 24Ex. and I set them at 10In 12ex, cold. Get them close, heat the motor up, and check the hot, then check them again when the motor cools. They do need to be pretty tight cold, so when warming the engine, I don't rev more than 2000 rpm. I'm not sure what you are talking about when you mention "preload". If your valves are binding agaist the pistons, you're too tight. I hope this helps.