Enjoy my pain: how much will I pay
 

A fun one here. My car is coming back to me soon after it was found to have a faulty (not broken) valve spring, probably stemming from being improperly timed after the timing chain tensioner/guide replacement at a different shop (regret of my life...). The car had a super intermittent misfire on cylinder 7 with no driving symptoms but a slightly rough (as in, normal for other cars, but not for mine) idle in park and neutral. All other possibilities were inspected before replacing the valve springs as well as re-lapping the valves on that cylinder, and all else looked good.

In any case, what do you think I'm going to end up paying. My independent mechanic is the only person other than myself that I trust with that car, and he's a true enthusiast. Solid, honest guy. Works at $96 an hour, which is pretty good for my area.

My guess is maybe 20 hours @ $96/hr + maybe $300 in parts (including head gasket, head bolts, miscellany, etc.). Something around $2250? I went into it preparing for something for something like $4-5k, so I'm not really concerned about how much it's going to cost. Just thought it'd be a fun thought experiment. If it comes in under my price ceiling, I'll just allocate the rest to other things (cooling hoses, water pump, thermostat housing etc., although I would do all that myself, so no labor cost there).

Have fun! Schadenfreude is ok every once in while.

about $1700. Honestly, I'm pretty happy with that.

You can replace valve springs without removing the head if you're careful. I have done it in the past,

Feed in a generous length of nylon rope through the spark plug hole and then bring the piston up until it smooshes the rope against the valves.

With the valves unable to move because of the rope, you can now remove the keepers, cap, springs and replace the whole lot as needed.

I would at least try this before you commit to pulling the head.

Oh, this has all already been done. Valves were replaced, too.

One of these days I'll learn to read the time stamps.

Valve spring cannot be faulty because of wrong timing. Valves break, not springs.
I would like to know compression in all cylinders.
If valve spring is weak (not likely), compression can be ok.

Shouldn’t be more than a one day job considering only one part
 

Well,

At a guess the spin would be 9x100+300=USD1200 .... but....
There’s always the incidentals as your mechanic digs into an old car. Other problems encountered might include split hoses and broken connectors.
That’ll lead to delays and additional parts costs.

I would say say an additional work day USD900 and another USD 200 plus not including standing/storage costs if the garage charges for this.

Total=1200+900+200=USD2300 PAIN!

That’s why it’s best to DIY if you can

Yeah, I DIY as much as I'm able to. But certain things on certain cars, I defer to my mechanic. On the beater I use when I don't have the Jag, I'm perfectly comfortable learning as I go along. But with this car, I tend not to be too intrusive. Given limited garage space, the family connection to the car, and the fact that it's the only car I own (not by choice, really), I can't really afford to make any learning mistakes on it. I intend on getting there eventually, though.

Compression was very healthy and consistent across cylinders. We expected sort of the same thing: a bent valve. But nothing was obviously out of wack except for a spring, which wasn't broken but seemed shorter than the others. In any case, all valves and springs were replaced on the offending cylinder anyway. It's worth noting that the misfire on cylinder 7 was intermittent and hard to feel from the seat of your pants. I tried pretty much everything short of taking the head off before handing that job to my mechanic to do some digging. Cylinder walls were fine also, and the engine was otherwise in good shape.

That's wise. You know what you're capable of and what needs to be left to a pro.