[JSeery]

Disclaimer, I don't use rotators! So, keep that in mind, it is possible I'm not 100% correct on this information. What I looked up for 1952 is 39 - 40 lbs at 1.89 install height. Need to install a valve guide with a valve and the retainer assembly on the valve (a little weight check spring is helpful, but not required). With the valve assembly (minus the spring) in place, measure the install height (from the top of the retainer to spring seat on the guide). Inside measuring dividers (the compass type with the manual adjuster) work good for this. Then measure the calipers to determine the install height. Now measure the spring pressure at this height, if the pressure is to low at the install height, then determine the shims required to get the spring pressure correct. Clear as mud I'm sure! Slightly higher spring pressure at install height is ok, just don't want it too high, saw something like 50 max.