Nope, not just the washer looking thingies, but the little silver collars around the valves that hold the collars on (valve retainers). The F retainers have a little groove in them that fits around the ridge on th F valve. The spring collar is also different, it has a 1.5 = 2mm larger hole. If you're re-doing an F head (and an appropriate name that is!
), take a look at the old spring collars under a magnifying glass, and make sure that they aren't starting to split. I had 2 on an old head that split, one broke in half and dropped the valve, the other was just split on one side, just waiting for the other side to let go.
Aftermarket springs from the K will work on the F. Check with
www.blackdiamondvalves.com (kibblewhite) or
www.megacyclecams.com or
www.m3racing.com for springs and retainers.
