Piston Ring Questions, Placement, Gap, etc. Options

[914four]

Getting ready to set up new 96mm Keith Black pistons with Hasting rings. There seems to be conflicting information for the need to check the ring gap. I'd like to make sure I install the rings and pistons correctly.

Is it necessary to verify a proper ring gap size?

If so, what is the proper gap how can I best check it?

Is there any difference in the two sets of seal rings other than a dimple on one of the rings? (they seem to be the same size)

The old Raby video shows the ring gap placement at about the 4 and 10 o'clock positions. Is this still the preferred position for the ring gaps?

[saigon71]

Just went through this:

I would recommend checking your ring gaps...it eliminates any guess work. All but one of my new rings were within spec. One was .002 tight, so I just filed the end of the ring down a little bit.

To check, insert a ring one at a time into the cylinder and push it into the bore with a piston so it's perfectly square. Then measure the gap with feeler gauges.

Your best bet is to contact Hastings for the recommended spec and the question about the seal rings being the same. It's hard to go wrong following anything Jake says about ring gap placement.

[r_towle]

There is no debate regarding verifying ring gap when building a motor.
There are those who check and verify every measurement, and their motors tend to last.
There are others who don't, and just bolt things together.

Please measure your ring gaps, they are never right.

Rich

[stugray]

Are these the Keith Black Hyper Eutectic pistons?

Did you get them from EMW?

Was there a sheet in the packaging that says that you MUST increase the ring gap over stock?

There was a HUGE debate over this years ago.
I got the pistons from Jake Raby. Jake said use the Rings "AS IS - They are set already"
The sheet in the box with the pistons said "INCREASE RING GAP OR ELSE". ( I still have the sheet if you would like to see it)

So there was a big argument over whether I should listen to the verbal instructions or the instructions that came with the packaging.

Well, I opened the gaps up some and split the difference between what the instructions said and what Jake said.

AND it was a dam good thing I checked the rings. One set had not been gapped at all.

[Mark Henry]

I run .015 on steel and I'm running .005 on nikasil. Sometimes bigger just because out of the box they often have bigger gaps.
I orientate my rings 10, 2 and oil scraper 9 o'clock.

[r_towle]

AND it was a dam good thing I checked the rings. One set had not been gapped at all.

This!!

(IMG:style_emoticons/default/aktion035.gif)

Trust but verify

[914four]

Thank you for the replies and I have further questions.

After installing the ring on the piston then into the cylinder, it looks like you need to have the ring just in the piston, even partially out to be able to measure the gap.

My flat blade feeler gauges are rounded on the end and will not get close enough to measure this gap so I assume there is a special type of feeler gauge to use in this case.

There is no paperwork with the pistons and Hasting does not give a gap recommendation. Should I use the suggested .005 for this type of piston?

[Java2570]

Do it like this picture shows.....feed the ring into the cylinder by hand and just use the piston top to square and straighten the ring. Then you can check the gap with the feeler
gauge.

[Mark Henry]

Is .005 what LN is suggesting?
On nickies Charles said you can run no gap, but you won't find a ring much under .005
That said on most tech I've researched tightening gaps doesn't make a huge difference, but at the same time new engines are running tighter gaps for emissions.

java shows the correct way of measuring the gaps.

[Bulldog9]

The deeper you go in the rabbit hole the more opinions you will get. Some say the upper ring needs a bit wider gap because it gets hotter and expands more. to NOT would cause the ring to expand and the lack of gap will cause it to break in the cyl.

KB said to open the gap by .010, Len Hoffman and Jake Raby said leave as is, Because they weren't uniform I just couldn't do that.

I set the top ring gaps at .020 and the second ring at .015, and filed the ends square
so I'm guessing going from the stock .015 to .020 is a met in the middle compromise. Most important to me is that the gap was even when compressed in the cyl.

The first pic shows the top piston rings and how they measured with a feeler gauge in the cyl. One said .022, but it was .020. All the 2nd rings were spot on at .015, no modification necessary.

** The 2nd compression ring has a dot that must face up. Pay attention, I goofed up on a couple and broke one taking it off..... Now I have a full set minus 1 ring. If you goof one up let me know I'll send it off your way.

[914four]

Great information!

This is the kind of information that service manuals assume is known through years of experience. I'm learning through the many years of experience of those on this board and hope to do it right the fist time.

Thank you all!

Kelvin

[914four]

My assumption is that you would use the cylinder that the ring is going in to set the ring gap.

[914four]

Is .005 what LN is suggesting?

No one has suggested any ring gaps. I was looking at the .005 from your earlier post. Got the pistons and cylinders from Tuttle so they could match the head work to the cylinders for me.

Kelvin

[Mark Henry]

Is .005 what LN is suggesting?

No one has suggested any ring gaps. I was looking at the .005 from your earlier post. Got the pistons and cylinders from Tuttle so they could match the head work to the cylinders for me.

Kelvin

OK, but be aware the small gap is Nickies, aluminum cylinders like in later 911 engines and from LN.
The aluminum expands more/faster than the steel ring.
I'd stick with no less than .015 on the iron cylinders.

[pilothyer]

My assumption is that you would use the cylinder that the ring is going in to set the ring gap.

By All Means, Yes.

[914four]

My initial checks show the compression rings to be close to the correct gaps with .022 and .015. The oil scrapper rings have a rather large gap that is too big for me to measure with my feeler gauges. Is there any concern for the oil scrapper ring gaps?

[r_towle]

This is a metal expansion issue, and for every set of rings, the answer can be different.

When I do this, I rely upon the manufacturer of the Pistons, rings, and cylinders to give me the proper guidance.

If th gap is too small the rings could seize in the cylinder within minutes of starting the motor for the first time, or once it really get heated up.

If the gaps the too large, compression could be compromised and blow by could be a significant issue on day one.

I have sent back rings and I have tossed specific rings if they do not meet the specs.

The other key measurement is the thickness of the rings versus the thickness of the grooves in the piston. You need that specific clearance number from the piston manufacturer. Steel and aluminum change size at different rates.

Rich

[porschetub]

make sure the ring is evenly done the barrel,measure the depth with a set of Vernier calipers,the rest...do what Mark says after that.

[Olympic 914]

Interesting ring gap article I came across when doing my rings. seems the gap is not as critical as the pressure on the cylinder wall. as rings wear they loose some of the spring pressure.

http://www.diagnosticengineers.org/journal...edge%20Gaps.php


looked up the KB pistons installation instructions and the ring gap should be { Bore x .0065} , so for my 96mm pistons I went with .025
2nd ring should go at .016, oil rings same.

I used the same KB pistons and Hasting rings that you have.

I have not run my engine yet so no info on compression

[r_towle]

Interesting ring gap article I came across when doing my rings. seems the gap is not as critical as the pressure on the cylinder wall. as rings wear they loose some of the spring pressure.

http://www.diagnosticengineers.org/journal...edge%20Gaps.php


looked up the KB pistons installation instructions and the ring gap should be { Bore x .0065} , so for my 96mm pistons I went with .025
2nd ring should go at .016, oil rings same.

I used the same KB pistons and Hasting rings that you have.

I have not run my engine yet so no info on compression

Well done, and this is what the OP needs to do, research...