Ignition timing using a dial gauge

[BSA500]

Sorry if this is obvious and I am being a bit thick but I have the head off and I would like to set the timing with my dial gauge. What would 5/16 translate to movement(thousands of an inch) on the gauge. Again don't think me thick I just can't seem to work it out. I would rather do it this way than the usual sticking something down the plug hole(to be fair it hasn't been wrong yet  ).
Oh its the A7SS thanks.
Andy

[bikerbob]

There are 1,000 thous, in an inch 500 in half an inch 250 in one quarter of an inch and 125 in one eight of an inch 62.5 in a sixteenth of an inch. so for 5/16" there would be 312.5 thous. But if you have the head off it is much easier to measure 5/16" than working in thous. Don't forget when measuring the distance it is always best to take the piston below the desired setting then bring it back up to 5/16"

[BSA500]

Yep that's the figure I got it just seemed a strange figure. Yep to taking it past the timing point because of backlash.
many thanks Andy

[bsa-bill]

Yep that's the figure I got it just seemed a strange figure

Well done , I like a mental workout now and then (not always correct result tho)
now for further mind warping turn it into degrees    best google it 

[Butch (cb)]

Yeah - I'm no boffin but in imperial units the 5/16 is just taken as 5 divided by 16 to give the decimal. I tend to find it harder to get a precise location on TDC. What with the piston sitting up there with no movement for a small part of the turn before it commences its descent, and my DTI never quite settling down on it's stand.

[BSA500]

That's the advantage I suppose of having cast iron barrels, the magnetic clamp stand really grips it well  . I used it to get the crank to tdc to set up the timing gears.

[bsa-bill]

. What with the piston sitting up there with no movement for a small part of the turn before it commences its descent,

Yes it seems that way until you put a dial gauge on it then it shows movement just about all the way

[shuswapkev]

have you ever checked the timing afterwards with a light and degree wheel???