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Several (most?) of the big Jap fours have you check the clearance with the lobes 'angled'. This means you only have to turn the engine over twice. From memory (and don't shoot me if I remember this wrong, it's years since I did this for a living..) T1 you check half the valves (all on no1, the inlets on 2, the exhausts on 4) and on T2 you check the remainder. The results are always the same as checking with the lobes at 180deg to the valve, btw, but it saves a lot of winding!

Tex, you have a way with words which often gives me a good laugh. Thanks heaps!

I agree with Steve. I always tend to do it one crank rev away from full valve lift (180deg on the cam). It's usually pretty easy to judge the full lift point by eye, give or take a few degrees. Base circle run-out is usually negligible so anywhere reliably away from the ramps should be fine. If in doubt do it in accordance with the manual. Valve timings are usually stated at a certain lift (1mm or something) which is after the ramps, but clearances are always (to my knowledge) quoted with the follower on the base circle. You sometimes have to be careful with finger follower arrange

To be honest, though, with an overhead cam I've always just checked the clearance when the rocker (or follower) is on the base circle: i.e. when the lobe is pointed directly away from the rocker/follower. It just seems easier than worrying about lining up markings, which can be error prone. Is that wrong, do you think? Does anybody know of an engine which specifies the clearances anywhere other than the base circle (i.e. part way up the quietening ramp)?

Correct, Steve. You check them after the inlet has closed and before the exhaust starts to open. This is sometimes referred to as 'on the rock' as the piston goes over tic the valves 'rock' one (or two, obviously) closing and the other(s) opening.

That worries me! Not telling you how to suck eggs, but that sounds like the crank was slightly off the marks and cam wasn't quite at the correct timing. It might be a good idea to double check. Ball ache, I know but better safe than sorry.

Spot on, Steve

Anyone who says different is on thin ice..

On my course we were told that you can't use feeler gauges to measure a gap exactly, nor to set it. The idea is that ALL dimensions everywhere in engineering have a tolerance - there is no such thing as an exact dimension. Suppose our clearance is supposed to be 0.17mm - it should have a tolerance specified, such as +/- 0.02mm. So the gap is allowed to be anywhere between 0.15mm and 0.19mm. The correct check for the clearance is to confirm that a 0.15mm gauge slides freely, and a 0.19mm gauge won't enter. That is the go - no-go test Tex refers to. What you don't do is check for a "sl

I'm struggling with the concept of Honda building an engine with adjustments out of spec. I just don't see it happening. More likely (to my mind) is 'enthusiastic amateur' mechanics not understanding 'go - no go' or 'sliding fit'. 'Back in the day' I had to do all sorts of adjustments to Moto-Guzzi, Ducati, Triumph & Norton bikes on PDI. The Hondas were always perfect. Every time.