as an aside I have worked in adult social care a few years now and have nvq's coming out me ears it does instill, if you want it, the ability to listen and communicate. It's transformed me completely (despite my keyboard moans on here LOL).
Thanks for putting up the pics. You say the rockers have been reused and the old heads did not have guide plates which could suggest they are the self aligning ones which can give you problems. You'll have to remove one and have a proper look.
MInd you I see good stuff in your photos. imo
The heads are held down using ARP studs and nuts (I can see ARP in their tops).
This block has the studs and allows you to drop the heads straight on. And crucially when fastening down it is with hardened nuts on the top of the heads.
The original method was to use long bolts - which scare me as they are highly torqued in to an old cast iron block and some actually go into coolant passages so you have to apply sealant - a real faff on. Studs you fit and forget and racers use them so it must be good!!! I did not have enough room in my car otherwise I would swap my old bolts out asap!
Thought I'd share this stuff as it is interesting engineering - to me. lol Again apologies if you are aware of this malarky.
This is the basic valve train set up. Cam at the bottom, cushioned on to the oil filled follower (lifters).
Pushrods take the lift up to the rocker which then push the valve down
Gotta love followers as they get pumped with oil and with the spring inside allow a fair bit of cushioning.
Illiminating the tappet noise found on other setups.
This fascinates me, the hole in the side is where the oil gets fed in to the follower, it then goes up the push rod, out the top of the rockers and flows down to valve tip getting splattered everywhere too. Genius
I have these roller rockers which just roll on the valve tip but some say there is such little movement they are pointless and IF getting serious with an engine you need the ones below where they have a roller bearing in the middle where more rotation happens.
Getting back to the adjustment I tried all the methods, some critics would say a stronger hand can turn the pushrods easier so it is only approximate when we all find the pinch point from which to adjust it down the last 3/4 of a turn.
But hey! Remember there is a cushioned area within the follower so getting really bogged down in the exact science is pointless. IMO