1. Is there risk of head damage due to faulty/sticky valve lifters?
Yes, there is a risk that there could be damage to the head, but more likely to the piston crown and valve stems/face than the head face itself. Turning the engine over by hand is not enough to determine a bent valve stem; that is just sloppy and I would ask them to take the head off, remove the valves and check for lateral play in the valve seats if they really are too cheap to just replace the head and rocker assembly together...which is probably what they'll end up doing anyway.
2. Would it have been possible for the piston to touch a valve if the valve was sticky or stuck, causing misfire?
I think that you'd know about piston/valve contact on a bigger scale than a misfire i.e. the valve would most probably bend or even fracture off, causing nasty things to happen, but I could be wrong. Theoretically, valve/piston contact would cause a lapse in timing that could trigger a misfire.
The best way to determine valve/piston contact would be to remove the head and take a look.
3. Has anyone experienced this problem on a new head (not to impressed seeing it was a
JCW head)
Not personally, but this is a risk with running hydraulic tappets in any car. One of the oil feeds in lifter arms may have become clogged with contamination from your oil, a possiblity if the particle was small enough and plausible since you have only just run in your car no? If not, was your car due an oil change soon?
4. Are the same valve lifters used on the
JCW head than a stock
MCS?
Yes, all the same valvetrain is used.
5. Is there any special way to "run-in" the new parts?
Don't stress the engine for prolonged periods at the same RPM i.e. freeway driving. You want to build up engine temp, but also vary the loads i.e. driving up some gentle inclines, then some town driving. Never go WOT for at least 1500miles and at that point, go for an oil change. Also, no going past 4500rpm for at least 1500-2000miles to allow for the piston rings to scuff the bores sufficiently and for everything else to bed in. If you are talking about just the head, then take it easy for 500 or so miles, and watch the oil pressure is sufficient if you have a gauge.
Hope that helps.
Henry
I have done 2500km after getting a JCW210 conversion done. I noticed a whirring phrrr type noise from around 4000 rpm upwards and went to the dealer. They listened to it and immediately decided to replace the harmonic damper (crankshaft pulley) This was done on Monday. It was late when I collected the car but I found the noise to still be there. Took the car back yesterday morning and took the main service tech for a ride. He was not sure what it was and said I should book the car in for a check today. Just after driving away the car started backfiring and making a constant loud ticking tappet sound. Managed to get back to the dealer with quite a very sick sounding car, struggling to idle at around 500 rpm. They have now traced the posible fault to a faulty hydraulic valve lifter/tappet. They took the tappet cover off and rotated the engine by hand. The valves open and close normally which should indicate that the valve stems are not bent, no springs are broken and there is no visible damage. They will be installing a complete new set of tappets/rocker arms/valve lifters whatever the correct name is because they are not able to isolate the suspect one. Questions:
Anyway 2 things worth checking are that the cam-chain tensioner was released after rebuild and that the tensioner is not faulty. Finally a compression check should reveal if anything touched (bent) .
