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melville wrote:A few degrees after TDC and the right exhaust will be off the ramp, possibly letting the cam rest in a more neutral spot, and with a little pressure applied via the feeler gauge shoved in under the rocker the cam can be shifted a touch toward the right.

Interesting...I've never heard anyone mention this before or it being a factor during setting valves. So, if one did set the gap as you suggest to the required spec, then there would be times during engine rotation where the valve clearanc would be less than spec. Is it a good thing to do this then? In my mind, it's best to err on the side of loose clearance (especially for the exhaust valves) rather than on the tight side.

Kurt in S.A.

Kurt in S.A. wrote:

melville wrote:A few degrees after TDC and the right exhaust will be off the ramp, possibly letting the cam rest in a more neutral spot, and with a little pressure applied via the feeler gauge shoved in under the rocker the cam can be shifted a touch toward the right.

Interesting...I've never heard anyone mention this before or it being a factor during setting valves. So, if one did set the gap as you suggest to the required spec, then there would be times during engine rotation where the valve clearanc would be less than spec. Is it a good thing to do this then? In my mind, it's best to err on the side of loose clearance (especially for the exhaust valves) rather than on the tight side.

Kurt in S.A.

I'm strictly TDC on my Boxer (2 or 4 cylinder) valve adjustments, and I get the impression that BMW wants us to do it that way. pkboxer noticed a curious effect of TDC adjustments when checked off TDC, and I 'splained it to the best of my knowledge. All else equal, I think adjusting at TDC will give the loosest overall clearance.

GSPD used to say it was not necessary to be spot on tdc on compression because the valves are closed either side of tdc.
Meaning that the cam lobes are not near opening either valve. If I recall correctly.

Easiest way for me to find compression stroke on lh side is to stick my thumb over the spark plug hole and feel/hear for escaping air when turning (knocking) the rear wheel in 5th gear.. tdc is not far after that.
Sometimes I might use my dipstick to tell me 'exactly' where tdc is instead of looking through the timing hole with a torch.
When I've set the LH valves, I knock the wheel around a little, push the dipstick in (maybe 1") Keep knocking the wheel around until the dipstick moves out again, guaranteed tdc on compression on RH side.

No harm is done to the dipstick or the piston crown. The dipstick lays almost horizontally when poking in the spark plug hole due to the angle of the hole and the thin dipstick. I can get to within .2mm of tdc with this method. Not that it is necessary to be that accurate.

ME 109 wrote:GSPD used to say it was not necessary to be spot on tdc on compression because the valves are closed either side of tdc.
Meaning that the cam lobes are not near opening either valve. If I recall correctly.

Easiest way for me to find compression stroke on lh side is to stick my thumb over the spark plug hole and feel/hear for escaping air when turning (knocking) the rear wheel in 5th gear.. tdc is not far after that.
Sometimes I might use my dipstick to tell me 'exactly' where tdc is instead of looking through the timing hole with a torch.
When I've set the LH valves, I knock the wheel around a little, push the dipstick in (maybe 1") Keep knocking the wheel around until the dipstick moves out again, guaranteed tdc on compression on RH side.

No harm is done to the dipstick or the piston crown. The dipstick lays almost horizontally when poking in the spark plug hole due to the angle of the hole and the thin dipstick. I can get to within .2mm of tdc with this method. Not that it is necessary to be that accurate.

That's the best part of OHC's - you can see the damn cam and you know exactly what's going on.

When you set the clearances on a six cylinder engine you use the rule of seven, that is, when the inlet valve on cylinder 1 is at full lift you set the clearance on the inlet on cylinder 6.

The same system works on our airheads, but you will have to work out the magic number yourself.

But no matter how you do it, the final check should always be with a " stethoscope" on a hot motor - you want the lightest of clicks inlet, slightly louder exhaust and both sides equal, and for some reason I rarely get that setting with feeler gauges.