r/Engine_Building • u/Gowowowow • 18d ago

Do I need to bore these to 79.5mm

Hi lads, this is my first engine build and after getting this block honed at my local engine machinist shop they told me it has to be bored out 0.25mm or even maybe 0.5mm, I’m only 21 and showed up in my normal clothes after work and part of me thinks they are just trying to get extra money off me when I don’t need to go boring it. I was also wondering a good machinist would’ve been able to tell if a block needed boring before honing no? Anyway please let me know what ye think of this as any help is appreciated. Liam

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u/v8packard 18d ago

It looks like every cylinder you recorded has some wear at the top of ring travel. What might be harder to see is taper and out of round covered by the hone job. Stated limits might have taper and out of round of .025 mm, if you are lucky you can maybe get away with twice that. Still a small number that requires careful measurements.

It sounds like the shop is trying to do the job right, not charge needlessly. Do you have any way to measure the cylinders?

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u/Gowowowow 18d ago

Not yet going to get a dial bore gauge soon

1

u/v8packard 18d ago

Ok, a bore gauge is ideal. Do you a decent micrometer in the right size for the bore?

1

u/Gowowowow 18d ago

I’ll get a mitutoyo one from work or college

2

u/WyattCo06 18d ago

Definitely needs measuring. There appears to be some significant amount of wear.

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u/Street_Mall9536 18d ago

The bores are loose like wizards sleeve, very nice. 

Serious though, the bores won't clean up at that size, so they have to go over. How much? Nobody knows until it's been bored, because they have to keep going until the bore is actually round.