no valve clearance

Hello Gents, hope you can answer a quick question for me, I am attempting valve clearance on a rebuilt head but have almost zero clearance (less than one thou)on 3 of the exhaust valves with a 2.0 shim, head is full reco with new valves,guides etc, I am wondering if it is possible to machine the underside of the bucket to creat more clearance?
Has Z1 Cammotion cams with shims top of bucket.Kz900,smog head,new cam bearings etc.I am guessing i have either a problem with the cam (doubtful)or valve stem heights incorrect.

any ideas? thanks heaps,

Kt

I don't think it's safe to grind metal off the buckets. Normally, the ends of the valve stems have to be ground but there is only a little way that can be done safely until the keepers can pop off.

"I am guessing i have either a problem with the cam (doubtful)or valve stem heights incorrect."

I really doubt it's the cam. The valve stems should have been ground by the machinist who did the head to restore original valve end heights. Low clearance can also be caused by cutting the sets too deep.

Thanks Bountyhunter, agree totally, "my" machinist is first rate, these things happen. Head coming back off!

Merry Christmas to all!
Kt

you can get thinner shims, that I'snt much clearance, not to sound stupid but you are checking em" lobe up right?

lemo32 wrote:

you can get thinner shims, that I'snt much clearance, not to sound stupid but you are checking em" lobe up right?

I believe 2mm is the thinnest shim available, hence his problem.

with valve in head, stem height should be no more than 1.499 in. or 38.07 mm according to my manual, swap valves or grind a maximum of 0.012 in or 0.3mm of valve stem end

Don't machine the bucket. You will have to tip the valves. There are gauges available for this.
racetoolz.com/

Thanks for all you replies and help guys, in process of removing my head, will have the valves machined. These things happen.

Jay, that link has some very nice additions for my home workshop!

Merry Christmas everyone, be safe and happy.

Kt:cheer:

I had the exact same problem, need to correct valve stem, I actually did machine a bucket before as a temporary fix and I had no problems but would not recommend it.Whatever was taken off the valve seat will affect stem height there after.