Quote:
Originally Posted by Bob 1967
The cover is 1 piece cast metal alloy.
I'll just accept that it's out and factor that in any future work, timing or valve clearance.
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It is just down to manufacturing tolerances then, our motors are probably all the same: +/- a few degrees. It will only really affect the ignition timing; perhaps this is a little reminder to all of us that precision mattered a lot less in the pre-digital age so it is best to set things up so they run well than by numbers in the book
PS. I was thinking about tis (as a surveyor) whilst Bobwalkin. It is perhaps not surprising that the timing mark can end up a couple of degrees out. The error balance for the chain of observations is quite large. First the hard to see mark on the crank, the parallax standard error in viewing it from an odd angle through a gap in the drive belts and pulleys must be a few degrees in itself. Then the inexact length of the belt (due to both manufacturing and wear) means the camshaft and auxiliary shafts can only be positioned +/- half the pitch of the belt teeth. Then there are parallax errors for observing both those marks. On top of that there is the positioning of the cover that contains the ignition timing marks.
Some of the standard errors will end up coincidentally cancelling each other out - but overall perhaps we shouldn't be surprised the visible error comes out to be a degree or two out.