Valve stem length

[sean_rfi]

Hello All,
I posted about this recently but I'm not sure how to proceed...
I've had the head for my Z900 A4 refurbed - k-line inserts and the valve seats refaced and ground to accept the original valves.
I then attempted, as best as I was able, to assess the valve clearances by fitting each valve and the cam with the head on the workbench. I appreciate that this is not likely to be very accurate and the clearances are likely to change when the head is fully assembled and fitted but it seemed the only way of doing the initial setup. By doing this I found that only 2 or 3 of the clearances were on the low side - 235 below. So ideally, I need to get at least two of the valves shortened a little so I can use all mid range shims. (I think it was Rob who very kindly responded to my last post and suggested that I do this)
My two questions are -
Is my method of measuring the valve clearances on the bench likely to be useful at all
and secondly can anyone recommend someone who can trim/tip the valves for me.

Thanks in advance,
Sean

[zed1015]

Bench shimming is normal practice to make sure you have enough valve clearance before fitting the head.
You need to measure the valve stem installed height to determine if you have enough scope for future adjustment and if not shorten the stems to suit.
There's a shim chart in the manual which cross references stem height to shim thickness required so you don't have to keep assembling the valve gear and cams to try different size shims.
You want to be as close to the minimum 37mm height as possible to attain the thickest shim.
You measure from the bare head casting with the valve spring seat removed.
It is very difficult to get an accurate reading with a steel rule or verniers because of the valve guide preventing getting close alongside the valve stem so you really need a height gauge like mine in the pic .
By the manual the valves can be tipped by a maximum 0.3mm to regain some clearance but if that isn't enough the collets and retainer height can be reduced by up to 1mm to allow further reduction of the valve stem length.

Contact Dave Ennis ( Forum member buzzard ) at Buzzworkz for the valve work etc as he's closer to you..

https://www.facebook.com/BuzzWorkz/

PICT1468_zpsd16d63cd.jpg (89.1 KiB) Viewed 1484 times

[sean_rfi]

That's brilliant - thank you very much.
Just the advice I was hoping for.

[Gray17]

Good afternoon guys,
Firstly i have done a search on the forum and Google and read several posts from this and KZ forum theres even a video but it wont open for me.
So im now at the stage of wanting to bench check my shim clearences before i re fit everything.
The head has been away and had new guides and seats re cut but their supposed to have trimmed the valves back to allow for this to maintain the clearence if that makes sense. But obviously i want to check.
So am i correct in assuming i slide the valve and cam bucket/shim then refit camshaft with bearings and caps but without springs/colletts, hold valve fully closed and measure clearence, do that for all inlets, then repeat same for exhausts but using exhaust cam? If not how should i do this?
Thanks

[sean_rfi]

Hello Graham,
This is pretty much exactly what I did. The valve faces had been resurfaced and valve seats had been recut and the valve stem tips appeared to have been ground to shorten them as part of the overhaul.
However, when I checked, in the way you described, I found two of the clearances were a little small - about 225/230. So this was when I posted for advice and Rob replied and suggested that ideally they should all be high 200s (close to 3.0mm as possible). In the end I decided had enough to do so dropped the head off with Dave at Buzzworkz and he would make sure it was all set correctly.
I'd liked to have set it up myself but wasn't entirely confident and didn't have the facility for grinding the stem tip if required.

[Gray17]

Thanks for reply Shaun, i can see that would certainly be the easier and probably sensible option, however in my case it would hold up my engine rebuild, which i would like to crack on with myself if possible. Having paid to have work done already seems a double whammy to pay again to have same work done. Plus im thinking if this is something that needs doing regular, its something i need to learn for myself. They said if any valves need further trimming they would do it for me if i told them the amount needs removing, alternatively they suggested if i have a bench grinder with smooth wheel, they would loan me their V blocks to do it myself, i know the theory, but not sure id trust myself with the practice!!! Of course they may all be fine but i still need to verify this before i rebuild the head.
Something else ive just noticed, gone to the cam caps and all the bolts are painted black, but half of it has come off, not good,i m now wondering if when it was rebuilt theyv used the outer casing ones instead of the chrome ones as noted from previous post they are the same size and my cam cover was painted black like a Z1B which now vapour blasted is back to silver alloy like it should be. When i think of the other mods they maybe tried to make it look like Z1B 3ven thogh its an A4 and ran out of money, hence why its half of 1 and half of the other?