Measuring bores, which tool to get?

[wil892]

Hi

I've finally got the chance to strip out the pistons on my GTD and see what condition the bores are in. To measure them I need a bore gauge but I think there are two ways I could do this.
Firstly I could get the telescopic gauges which are then measured with a micrometer (which I would also need to buy) or I could get the dial bore gauge which obviously would show the specs on the dial.

Which is the most accurate? Obviously if I did it using the telescopic way I could use the micrometer to measure the piston diameter as well. How does everyone else do it? What kind of accuracy do I need, 0.01mm?

Thanks
Will

[rabbid79]

The nice thing about the bore gauge/dial indicator is you can easily run it up and down the cylinder to check taper and various other defects.

[wil892]

True, and I think it would be easier to take readings from. How important is it to measure the pistons. I they are out of spec should it be visible? I'm hoping the bores are within spec, so I can hone it and get the pistons nice and clean, reinstall with new goetze rings and get my compression back. Last time I looked which was 20k miles ago I could still see the cross hatch but there was some crud on the pistons so thinking it may just be sticking rings on one or two cylinders.
I'll also be able to check how the chinese head casting has coped over that mileage.