Valve Lapping... looking for some words of wisdom

[jmgtp]

I have a set of 0 mile heads going on the car. Though they have no miles they have been sitting for years and the valve seats look a bit oxidized/tarnished. The valves going in are from a 120k mile engine. I plan on using a chemical of some sort to clean the valves before lapping.

Questions:
1) I plan on doing this by hand. Are the simple suction cup tools good enough? They have some cheapo's on ebay.
2) In the course of lapping I'll be sure each valve is used to lap a valve seat. However, is it important that the valve that laps a seat is installed into that seat?
3) Since the seats are presumably new, and the purpose of lapping is to just clean them up, should I stick with the finer compound or still start off coarse and then lead in to the fine stuff?
4) Since the valves have a good bit of use, how can I spot a burned exhaust valve or other kind of defect? Will it be obvious?

v6z24 has a decent write-up: http://www.v6z24.com/howto/valvelapping

Any veteran words of wisdom?

I'm planning on getting this done near the end of November and I'll likely take pictures to document removing the heads, disassembly of the valvetrain, lapping and reassembly.

[Superdave]

I only use fine grit for lapping, Basically just look for pitting in the valve or anything that dosen't look quite right. The regular suction cup hand tools work ok as long as the valves are very clean and it can stick to them.

If you lap a valve to a seat, always leave it in that seat.

[jmgtp]

Thanks Superdave. I'm probably overcomplicating a fairly simple process.

Any recommendations on what to use to clean the valves? I'm sure carb cleaner would work but I'd probably have to buy 10 cans worth. Is there anything over the counter that I could get a gallon of and let the valves soak? Then hopefully a rinse under the faucet and they'd be clean?

I'll have to devise a method to track what valve goes where.

Anyone know what kind of metal the valves are made of? The valve spring compressor that I have isn't quite pointed on the part that contact the valve face but it looks like it could inflict harm on a soft metal. I might work some kind of rubber foot onto it.

[pocket-rocket]

I've never harmed any valves in any engine using a valve spring compressor. I also put them in the same seat, but I tend to start with course, mix course and fine for medium, then finish with fine, but that's me. I also used a cordless screw gun on low speed on the stems of the last ones I did. I've never had the best of luck with the suction cups, even with brand spanking new valves. ForcedFirebird raves about Formula 88, but Ben and I searched all over Warsaw, and I checked around here in Elkhart and no one had it, so it might only be sold down south, but check around for it just in case. As for spotting a burned or defective valve, I imagine once it's clean it would be pretty easy to spot something like a crack, or after you lap it you would be able to see where the seat area wasn't cleaned up from being warped or pitted beyond acceptable levels.

[Superdave]

I use one of these..




He loves sandblasting.. hehe

[55trucker]

While you are doing the lapping.....periodically stop and wipe off the compound and check for the contact *ring* that will become visible on the valve face.....ideally you want it to be in the center of the face but if it is slightly off to one or the other direction that shouldn't be of concern, the pattern should be uniform all around the valve face (the same goes for the pattern that you will see on the valve seat). If the pattern is close to the valve *margin* that can indicate that the mouth of the seat needs to be slightly opened (multi angle valve work)up to move the contact point (but not much at all , you don't want to *sink* the valve) to keep the pattern in the ideal location (if the pattern IS close to the margin there is a chance that the valve can burn out). Also, if you have access to the specs and a vernier caliper, check the installed height of all the valves, this again will let you know if the valves installed height are within specs and if any of them are sitting *deeper* into the heads than the others, ideally you want them to be all the same dimension. Have at it.

[pocket-rocket]

I use one of these..




He loves sandblasting.. hehe

And I thought I was the only one with their old home theater receiver in the garage for a source of music out there...

[Superdave]

works like a champ!

the cd player is full of dust and won't play anymore though...

[SappySE107]

I would consider lapping for intakes, but 120k mile exhaust valves are probably pitted pretty bad. Your seats look fine now, fine crossbuffs cleaned off the oxidation look no problem. I would get new exhaust valves or see about how much needs to be taken off and if the margin thickness is enough after recutting the seat area on the valve.

[pocket-rocket]

works like a champ!

the cd player is full of dust and won't play anymore though...

I either plug in my iPod nano with a "y" adapter or plug in my laptop with my wireless adapter to play music off of my desktop in the basement over the network.

[jmgtp]

Damn, I was hoping it wouldnt be a problem to reuse all the valves. New exhaust valves are looking to be at least $150 for all 12. Is it visibly obvious to tell if they aren't any good?

[SappySE107]

You would have to measure the margin (flat spot at the end of the valve head) and see how much you can possibly remove and then compare to what needs to be removed. Unless you have done valve refacing before, its no going to be easy to judge by looking.