New rockers, no gap

[71Westy]

Just replaced all the rocker arms and pushrods (warranty replacement from the company that supplied my engine due to some faulty arms/rods). But... the gap on two of them (both on same cylinder) is tiny (probably a couple of thou) and non-existent (ie the arm is resting on the valve). What's going on? I've swapped the pushrods around and no difference.

I'm wondering if I've done something wrong - I've fitted and removed it a dozen times and to no avail. I've swapped the two arms around, and that changed it to one that I could adjust and one that was still very tight. I've rotated the engine to make sure the pushrods were seated. A very depressing evening as it was going well (the other head is fine).

I'm wonding what the hell to do - I'll call the supplier tomorrow but I was due to camp in it this weekend :-(

Thoughts?

Nick

 

[Marvel]

The pushrods were all exactly the same length?

 

[crede999]

Possibly worn valve guides ...were the heads new ?

 

[71Westy]

As best as I can tell, the pushrods are the same length (I've used two rulers across all 4).
Shouldn't be valve guides - these are brand new heads with 5K miles on them.....
Hmm

Gonna refit teh old ones tonight and see what happens. Plus I have a call out to the supplier.

I did notice some rockers have a code then a 1 on them, and some a 2. I take it they are all the same?????

Nick

 

[Trikky2]

Have you checked the valves by putting a straight edge across the tops of all four - to check they are all the same height?

 

[Anonymous]

Sounds like the valve seats may have recessed into the heads happens on Mexico heads

 

[71Westy]

They do look to be in line, although in the dark last night I was losing the will... so could have been making mistakes. And the one at fault was on an inlet valve (I would have thought recession would be on exhaust valves?).

It has to be said that all of the new rockers are tighter than the old ones - I had 2 or 3 threads exposed after the locknut - now I have 4-5.

Anyway, the supplier is sending some 60 thou shims for the shaft mounting which should sort it. I can only put it down to the profiling of the new pushrods or the machinging of the rockers - the pushrods are the same length as the previous ones.

Nick

 

[71Westy]

Just a follow up - I put two old rockers back on and hey presto. Gaps back to normal. So it looks like the current batch of rockers are machined less.

One problem I do have is that the M8 nuts that hold on the rocker shaft keep stripping if I try the 25 Nm (18 ftlb) recommended torque. Not encouraging. I have used BZP nuts, not softer stainless. Hmm. I'm due some new pucka ones tomorrow but I'm a little concerned.