or the piston inside is sticking.... all i can come up with...
designed for no or low detergent oil and now we use oil that keeps a lot of the particulates suspended...some certainly get through the filter.
for mys sins i have 2 hemi 265 engines from Australia that use the same lifters, that do this consistently. 2 engine doesn't make it the Rule but 2 in the hands of the same fella....
standard oil pump is governed by a spring/bypass valve that allows no more than about 55-60 of oil pressure and mainly settles to 40 when hot. avoids winding the impeller or drive gear off the oil pump shaft
one engine a worn out old bag of nails the other rebuilt and time and effort put in to make sure it was all good.
didn't matter what I did about preload the things would pump up to a position where the clearance was still just too much, yes they pump up but in a lacklustre way like they can't be bothered
after a lot of work i gave up, went solid lifter with adjustable rockers
they still rattle abit but not as bad as before
and this is why these motors get called rattleys in Oz....
Presume by design they have a potential to do this and something has made it worse over the years, oil modern lifters or ware....
Chrysler Oz only did experimental engines with solid lifters so no real spec for clearance shared with the public, so all we have is what a modern the cam grinder says, and he usually says 20 thou on inlet and exhaust. When they actually they could probably benefit from something closer to slant 6 spec
i did an awful lot of work to find out why one would rattle one day and another would pick up the batton and do it next day only to have 3 doing the day after.....
followed by a week of blissful silence
absolutely infuriating
i.e i feel your pain but i can't help :) other than take them out clean them out and try running standard sae 20 or 30 with little or no detergent or whatever a 360 was designed for,
which is probably a bad move given advances in oil tech
Dave