I've been driving the car for over a year and a half now and decided to do valve seals when I noticed the exhaust valve on #4 looked like it wasn't moving as much as the others, there's always been a tick that's about half the speed of the engine (you can hear it in the video) coming from the passenger side of the car and I've never been able to pinpoint it, it may have always done this, I do not know, this is my first time adjusting the valves with the covers off while running.

heres a video:
Collapsed lifter? bad cam lobe? what do you guys think, and what should I do now?

 

I'd suspect the cam lobe, esp if it's a flat-tappet (tappet is another word for "lifter") type as opposed to roller tappets.

 

It's a flat tappet, the push rod still spins but I wanna change the cam out to a roller anyway, I saved all of my roller cam top end stuff from my old 305 tpi so I'll just swap it all over and use this comp cam: link

would the engine need to come out and get rebuilt or will I be fine swapping it in? My oil pressure is as good as the day I got the engine running

 

Generally you can do a cam swap with the motor still in the chassis. In these cars though, the radiator and the piece right below the hood latch needs to come out, and maybe the AC condenser (might not have to come all the way out, just loose).

 

So what's the thought on metal shavings from the cam lobe damaging the rest of the engine?

a cam swap in the car is easy. Just a bit of time. I had to have my radiator fully out. I was most frustrated with having to loosen the oil pan a little to get the timing cover off. It worked fine but was just more of a pain to deal with.

 

For what it’s worth I run a no bypass oil filter adapter with the non bypass wix filter specifically for this reason in case if there ever was a cam failure the metal shavings would be caught by the filter before it could circulate into the bottom end.


I was reminiscing today at work and now I’m pretty sure I actually can pinpoint when the failure happened. It was probably right after I got the car on the road more than a year ago, I was doing a test run on an abandoned stretch of road near an old airport to see what my 0-60 was and I remember coming to a stop and it sounded like the engine was knocking, I shut it off and let it sit for a minute, turned it back on and the knock slowly went away, probably the lifter taking the slack after the lobe ate itself… oh well


found the roller top end stuff from my donor 305, a good cleaning and I’m off the races (one of the lifters are missing in the photo because it’s on my desk)

 

Depends on how much, how long they've been there, how much of it has got past the oil filter, etc.

You'll have a better idea once you pull the cam.

Personally I'm not all that optimistic, butt hay, some people are ALOT luckier than me. The only luck I ever have is bad, mostly REAL BAD, so I've just kinda got used to that over the years. Yours might be better than mine.

 

Yeah, that makes sense.