I bought a Mac 1 with a pinto 2.0 (bored out to 2.1) which has had a piper 285 cam fitted, along with a modified camshaft pulley. Engine seemed to be misfiring so took the rocker cover off to discover a follower has come off its spring so wasn't in contact with the camshaft (answers the misfire!) doesn't look like its caused any damage though.
My question is any idea why has this happened after it has been running fine? Also as I didn't do the original build/ engine upgrade I don't know if followers/springs etc were upgraded at the same time as the camshaft, any idea how I would tell? The main question I guess is how to avoid this happening again? Any help would be greatly appreciated!

has a valve been sticking open? I wonder if that might be the cause.

I wouldn't just pop it back on and hope for the best in case it happens again and causes real damage.

No the valve is closed, no I want to do it right but confused by not knowing what's been put in there and what would need changing after this happened

Sorry get what you mean now, don't think the valve was sticking as it was running fine, heads coming off so can investigate further

Maybe the follower pillar worked loose. I've had them do this before if they are not really tight. I just had a bad rattle, but if it goes far enough the follower can jump out.

Has it got uprated valve springs to suit? Or double springs fitted? If not valve bounce may be the cause.

As old timbo says the pillar/ locking nut will have come loose and the follower came off. Happened to me, put it back on and put a new retaining clip/ spring on it and it has run perfectly for the last few thousand miles.

Ditch

It's not unheard of for a pinto to spat a follower out, at best the valve gear is best described as agricultural.

I wouldn't take the head off for this (unless you have other reasons to warrant it coming off) refit, recheck/set all the clearances and forget about it.

It's fiddly but you can locktight the ball stud and lock nut
Valve springs can only be tested in a valve spring test rig, a pillar type spring compressor with a guage.
The only other way is to measure the valve spring installed height against the manufacturers spec
Most 285 Pinto cams use single valve springs on standard spring seats

At the same time I had frothy coffee in the header tank and water was pressurised so heads coming off so I can check for any damage at the same time. Pretty sure I got away with it as it was running before I discovered the follower had moved, on that matter would you recommend getting head skimmed as a matter of course or see what its like when off before deciding? Thanks for the replies, grateful for your help!