Re read my first post, and check to see if the valve guides have excess side clearance.
Fraud's in aussie had a problem a few years ago, they removed tooo much "tin" from the cast iron mix and the life of valve guides was about 10 mins., I know as I worked for them back then and it was my job to fit new heads if the previous one developed a tick. I was fitting two heads an hour ( 6cyl ), and there were 4 cars each needing attention, kept me busy for several days until they finally went back to the original cast iron mixture. I was even dismantling the heads before fitting and giving them a generous amount of oil, it didn't help, thats the fraud way of doing things,
always trying to save a few pennies and not worrying about quality.
