" From: farna@xxxxxxx " " I agree the heads were probably set up for some alloy valve that would " take the higher exhaust heat. Could have been stainless in the mid 60s " though, not sure if sodium filled were around! something like stainless " would definitely need to be larger in diameter to take the heat though. sodium filled exhausts were well known in aircraft engines as far back as ww2. it's not impossible that they were used at indy of all places, with its early adoption of turbocharging and very high outputs per cubic inch. ________________________________________________________________________ Andrew Hay the genius nature internet rambler is to see what all have seen adh@xxxxxxxxxxxxxxxxx and think what none thought _______________________________________________ Amc-list mailing list Amc-list@xxxxxxxxxxxx http://splatter.wps.com/cgi-bin/mailman/listinfo/amc-list