Topic: Dumb question: what do cam tower pucks do?

[The Gurg]

Why isn’t there metal where the cam tower puck is?

[seanbarney41]

because you wouldn't be able to remove the cylinder head screw (or is it a nut?) that lies underneath

[754]

Not only that , even  if there was no fastener, you have to get the sand out after the casting of the head..
 If you can't see if any is left in there, that would not be good.

[The Gurg]

Right, I removed the head, so I should know that. Thanks. Looked all over google for the answer. Just needed to actually be in front of the engine.

[PeWe]

Those pucks are there to cause leaks of oil
Non hardening sealer on the shelves in these holes before pucks goes on to ensure no leak. Not too much, enough to  cover the outer edge of the puck .

[The Gurg]

I need a video of the right amount of 3bond to apply to the pucks! The time is coming!

[PeWe]

You will see. Apply an even amount aroubd the holes. Let cure  20 minutes ir so.
I hope you have verified that all threads are OK, cam studs not creeping up . (Very small radius of alu follow the  stud were attached into head)

Place the pucks, press down a little. Wipe off sealer coming up.niw time to rest mount rhe cam holders. Tighten them a little. Remove them an wipe off the overflow of sealer. Use acetone on the cloth to clean quickly.
The area close to the oil orificies mist critical to not get any sealer overflow .
Mount the  cam holders again and tighten the bolts and nuts.

 Very important to not tighten too much.
10Nm can be to much as I have seen ( OK with Time-serts glued ).
 If no thread inserts only soft alu, 8Nm (6ft lbs). Honda specified too much and threads will go bad. Not good when engine is revving.

[The Gurg]

Got the cylinders on.

PeWe
How do you verify cam studs aren’t creeping up? Double nut them and torque or just check by hand?

Are you adding Threebond 1184, letting it dry for 20 minutes, then adding the pucks or adding threebond, placing the pucks, wiping the excess and letting it dry for 20 minutes before mounting the towers? Assuming it’s the latter.

The amount of threebond should be a thin film?
 
Which bolts are you only torquing to 6ft lbs in the head?

[PeWe]

If you look close to where studs enter the head. If it has started to creep up, there is a small radius of aluminium follow the stud. Very little, maybe 0.5mm. That is what I have seen.

I add the sealer and let it dry a little so the puck will raise a little bit over the head surface to ensure pressure when cam holder is mounted.

I have placed the pucks direct too so they stick to the sealer.

I torque all of the M6 by 8Nm 6 ft lbs). If thread has a healthy insert, I tighten harder. Max 10Nm (7.3 ft lbs)

I tightened all by 10Nm before. Honda specify more. I got some bad threads that way.

Honda shop manual specify 6.5-9.4 ft lbs on these bolts and nuts. 9.4 ft lbs is 12.7 Nm. I remember I tightened by 12Nm back in early 80's so I know why all threads were stripped.

Both my bikes had time- serts in all cam holder threads. Except for the later head my K2 got last fall replacing a smoking K1 head. A very fresh and probably never worked on K6 head. I think I tightened 8-9Nm on all.

Max torque for grade 8.8 M6 is 9.8Nm.  I wonder what max is for aluminium thread? Honda's bolts are forged and withstand much more than the threads can.
They should have specified 8- 10Nm (6-7.3 ft lbs).

It is rather thrilling when tighten the nuts on the studs when enter the 8Nm area and after. The wrench should feel firm and click when reaching the torque.
A bad thread will click later and feel softer. Then you know it will soon give up.

The small M5 holding the rocker shaft 5 Nm ( 3.6 ft lbs).

I have a good 1/4" torque wrench 2.5-25Nm I trust.

[ekpent]

  I tore down a 750 engine to repair once and when I pulled the cam towers off was surprised to see someone had used just regular o-rings instead of the nickel size flat disk pucks. Guess it would still work but of course I put it back correctly. Never know what you might find inside these old bikes.

[754]

I would wipe off pucks, install dry, then see how high they sit.. then decide how much sealant to use. If they are sticking above you won't need much.  I have at times re used them.

[PeWe]

+3  reuse
I have reused them too. If they are not very old and hard.

[campbmic]

I should have a spare set of those pucks in my old kit if anyone needs them (just pay postage). PM me

[70CB750]

  I tore down a 750 engine to repair once and when I pulled the cam towers off was surprised to see someone had used just regular o-rings instead of the nickel size flat disk pucks. Guess it would still work but of course I put it back correctly. Never know what you might find inside these old bikes.

Technically there is no reason for pucks, O rings would do. 

Actually having a groove for o ring around a hole would be the best solution.