Valve clearance after valve job 1982 GPZ750

So this is a follow up to an earlier post. My 1982 GPZ750 head was taken to a local machine shop and given a valve job. After bench testing, the clearance on the intake valves was unchanged after the work. On the exhaust side however, there is no clearance even after installing the next to the thinnest 2.05 shims. If I order new exhaust valves and give them a quick lapping would that give me back some clearance? I do not want to grind down the valve stems, and I do not want to take the head back to the local shop as I'm not feeling too kindly towards them at this point. Thanks in advance, Mark

The main reason why people go 1mill over on valves is that is all that will work with the head anymore.

What does that mean exactly, 1 mil over? Over sized valves?

yes oversized because there iss not enough metal left to work with. they dont sit down in as far.

Where can I get those, and would they need to be lapped in?

a good machine shop would have known that your old ones wouldnt work. new vales need new seats cut. You can get some room on the old ones if they tipped .30

"Good machine shop" is certainly the variable here...

New valves may sit a little higher, but it depends on how aggressively the shop faced the old ones. In my opinion the proper fix is to tip the valves. Even if you get new valves I'd tip them before install, otherwise your engine is going to enter service with all the shims right near the very bottom of the available shim range.

I just redid my 750 head, including cutting the seats and facing the valves, and after tipping the valves all my shims are in the 2.50 range or fatter.

Where you say tip the valves you mean grinding the ends of the stems? How much did you take off?

Madtrout wrote: Where you say tip the valves you mean grinding the ends of the stems? How much did you take off?

The machine shop faced the valves and tipped them, and I'm not sure how much they cut, but as we discussed in your previous thread I think you are safe to cut them something like .010" before you have to start managing how far the keepers are sticking up. And FYI, Jay from APE said that they kiss the keepers a little to get even more life out of the parts. This may seem extreme, but the keepers stick up quite a bit above the retainer so shortening them down doesn't hurt the parts in the least.

Thanks for all the feedback. I'm going to call the machine shop on Monday and insist they make this right. And I was so looking forward to reassembly this weekend! Glad I bench tested it first. Mark

At this point I would have them "tipped".
Steve


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