Engine Cylinder measurements before and after boring

[Hamza]

Hi guys,

Working on a 79Z..

So I got the block bored out to 65.00 mm. I asked the machine shop to give me 0.04 mm of piston to wall clearance. Cylinders were not too out of round except cylinder 5 which I felt may need some work. Engine is in good health otherwise from the looks of it. Pistons from cruzinimage and then inspected under a measuring microscope (a tad of an overkill..had access thought i would break out the big guns).

I miced the bore gauge to 65.00 mm and took the following readings. My table shows the min and max recorded post boring. Before boring the table shows preop measurements. I read clearance is from 0.01 to about 0.09 mm?

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Pics of pistons measured 10 mm up from skirts. Effectively i think ill get a minimum of 0.02 mm if i match pistons to wall clearance. The issue is that I asked him to give me 0.04 mm across all cylindera, he reckons he measured all the pistons and cuz they were the same he bored it based on the one...I reckon thats a bit lazy and may explain the variation.

I think I can make it work...looking for some candid advise!

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[Crazy Canuck]

This is an old post, but I’ll give you my .02

On initial start and for the first while when breaking it in a fair amount of wear will occur while the parts are getting used to rubbing against each other. I’m sure if you go easy on it the first while it will be all good in the end.

And ya....getting the microscope out is a little over the top.....these are just machines that run just fine when many things are not “perfect.”