You need to remove the valves and measure the stems with a micrometer. The service manual and technical manual, with all the measurements, have the stem sizes. You can also remove the keepers and springs and do a rudimentary check by moving the valve head back and forth.

The guides can easily be removed and replaced using a liquid CO2 to shrink them. Use new headbolts and lap the valves while your there.

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Regards

Warren

Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor

Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL

ENTER > = (HP RPN)

Not part of the in-crowd since 1952.