Topic: tappets, valve tops and cam cover replacement

[hymodyne]

morning,

I'm trying to re-assemble the top end of a '72 500/4 following a gasket replacement.

I set the cam cover on and tightnted bolts gradually distributing the tightening down as evenly as possible. I got the cover in place and began to set the tappet clearances. after cranking it over a few times, I noticed that there was a distinctive "Ping!, or snap!"when certain tappets pushed or released from the valves. I took my screwdriver and used it to pry loose the tappets that have goten caught at the edge of the valve top, as per the manual. after doing this, I would still hear that sharp tappet-to-valve sound, sometimes regularly, from a specific tappet, and other times very intermittently; sometimes it wouldn't occur for four or five kicks of the starter. last night, I was adjusting tappet clearance when I tried to kick it over, and it wouldn't budge. I wired up the starter, and it couldn't move the engine either. OK, something's stuck, so I quit for the night. This morning finds me with the cam cover off, and the engine turning smoothly without the cover, but there are little nips and chips on the tops of the valves where they contact the tappets. what should I do before I re-assemble, and how can I eliminate that "Ping" ?

[Tim.]

COMPLETELY back-off (perhaps even remove) the tappets before replacing the valve cover.  Then, go through the tappet adjustment process.

Something didn't get aligned the first time - hopefully you didn't bend anything (i.e. a valve).

One trick is to use elastic bands stretched from the intake tappet across to its exhast tappet partner - this holds them up so nothing gets in the way when placing the valve cover back.  However, still back the tappets right off when putting the cover back on.

As you go through the tappet adjustment process, make sure the tappet lines up perfectly with the valve.

Do you have the manual?  An extremely-high quality version is available for download here (300+MB).

You mentioned gasket replacement - head gasket?  Did you have the cam shaft out of the engine?  Are you 1000% sure it is back in properly (align slot on right-end of cam level with the engine, etc. etc.)?  If things were 'stuck' you could have had the piston up against a valve, suggesting the cam isn't in properly.  Double check this.

[Tim.]

By the way - 'nips' and 'chips' sound really really bad.  Any pics of this apparant damage?  Did you do a valve job (lapping, seals etc.) when you did the overhaul?

[TwoTired]

Sorry to be the bearer of bad news.  But, from your description, you have bent some of the valves due to improper installation of the valve cover.  There is a section in the Honda maintenence manual the warns about and describes this procedure.  Since the bent valves don't slide easily in their bores anymore, due to being bent, they stick, and when they do release, they ping (valve spring ring).
Time to pull the head off, Im afraid.