Piston Ring's Gap 72mm

So do I need to check the ring gap in the cylinders? Do I do this from the top or the bottom of the cylinders?

yep, you need to set ring gap.

where the two ends of the ring come toghter when placed in cylinder bore, manufactures recommend a certain clearance.

I would push ring down about 1/2" in the bore to measure gap.

DobbinsCMA wrote: So do I need to check the ring gap in the cylinders? Do I do this from the top or the bottom of the cylinders?

I think you check it at several points up and down the bore, haven't done it in a while. I recall the proper nominal end gap is about .003" - .004" of end gap PER INCH OF BORE DIAMETER.

I think service limit is actually about double nominal which sounds like a lot but there isn't that much compression loss at the end gap point, most of it is past the rings in the piston grooves.

That means I should be able to get 10 sheets of paper between the ends of my ring? Cuz it looks pretty small in my picture. 1 sheet a paper is 1 mil or .001 inches. What do you think about the gap?

DobbinsCMA wrote: That means I should be able to get 10 sheets of paper between the ends of my ring? Cuz it looks pretty small in my picture. 1 sheet a paper is 1 mil or .001 inches. What do you think about the gap?

No, you go buy a set of feeler gauges.

10 pieces of paper, give me a break.

go to AutoZone and spring $8 for feeler gauge........ :whistle:

Well I have this cool thing called a micrometer that measure to the ten thousandths place of an inch. I measured each page (thicker pages than normal paper) as being .01145 or .011. That being said, yes I would love some but why buy them for one use? Do you want to send me the money? Give me a break. Normally yes I would agree that the right tools matter when doing such important measurements. But thank you Dr Gamma for your reply.

What I am asking is .0113 inches the right gap at .004 for these rings? Thats all.

Stupid question for you Mr. Dobbins, what are you planning to use when you check your valve clearance??

That fancy micrometer??

That is a good point. I guess I could but maybe I should get some. Though I do not appreciate your negative judgmental tone. This a place to help people not to be a jerk. Notice how 4TheKZ1000 said the same thing but not in a way that made him look like an condescending arse. I do not do this for a living nor do I pretend to be a professional so I understand that I may be a little ignorant.

Now back to my initial question of the gap for 72mm rings. Since you are so very experienced do you think you could give me a double check on my math? That would be most helpful Dr Gamma.

Wiseco recommends setting the top ring gap using this formula-(bore size(in inches)) X .0040 Say your bore size is 80mm then 80/25.4(mm/in).15 in. X.004= 0.012 in. end gap

www.wiseco.com/PDFs/Manuals/RingEndGap.pdf

you would not want to use paper because you want to be able to "feel" the drag of the feeler gauges.
rings are either cast iron or chrome-moly,which are both much harder than paper and would be impossible to get the same "feel"twice .

hth,
leon

It also helps to make sure piston is sitting level/square in the bore when measuring.
Take a piston and shove it in upside down in the bore using it to square the ring up about midway down the bore, pull piston back out before measuring.