[dennislbrooks]

Also, did any of the spark plugs have a little rust on them or did you have a cold miss until warmup. The 283 heads (and others) have hairline cracked before between the exhaust and intake valves that once the heads are cleaned can usually be seen. When the engine cools, antifreeze will slightly leak into the cylinder. You may want to magnaflux the heads when the head work is done.

If you have this condition, I think the head is usually a throw away. Maybe you already know you do not have this problem.