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  View original topic: AA 95.5mm piston ring gap question
Pascal Fri Feb 18, 2011 5:43 am

So I have my new 95.5mm AA piston and I'm checking the ring gap. Everything I've read says they come with Hasting rings, so I checked their website for the specs. The spec says for 3.5425" to 4.3299" cylinder diameter the ring gap should be .012 to .022". My ring gap seem to have a sligh wedge shap to them with a little machining ridge near the outside edge of the gap that prevents them from closing up flush. I can get a .020" feeler gauge in the gap but it gets tighter as I push it in toward the outside of the ring gap. a 0.018 feeler gauge fits all the way in the gap fairly easily. With that large of a gap should I be concerned about the ends of the rings not mating up tight, or should I try to file them to get a better closing gap. I'm concerned that because they are so close to the upper spec that filing might take the gap over the spec. Thanks

morymob Fri Feb 18, 2011 6:09 am

Did u try putting ring in upside down look ing at bottom, this might help to see /measure that area. I have used lots of Hasting rings but none with what u describe.Maybe this their attempt at Sealed Power method of sealing the gap and stay clear of a patent .

Pascal Fri Feb 18, 2011 6:39 am

I'll post some pictures to clarify things.

tencentlife Fri Feb 18, 2011 11:33 am

0.003" min gap per 1" of bore. Larger is not a worry, smaller is what presents potential disaster. Yours are more than fine, but I have one question: how is it that filing the ends will close a gap? I'm only asking because I want to live in a universe where every time I say "I've cut that board three times and it's still too short" would get me a free beer.

turbotransporter Fri Feb 18, 2011 11:45 am

tencentlife wrote: 0.003" min gap per 1" of bore. Larger is not a worry, smaller is what presents potential disaster. Yours are more than fine, but I have one question: how is it that filing the ends will close a gap? I'm only asking because I want to live in a universe where every time I say "I've cut that board three times and it's still too short" would get me a free beer.

:lol: Funny stuff. After over 20 years of residential remodeling I like: "measure once, cut twice, get a new piece of wood" :roll:

Pascal Fri Feb 18, 2011 12:00 pm

tencentlife wrote: I'm only asking because I want to live in a universe where every time I say "I've cut that board three times and it's still too short" would get me a free beer.

:lol: , well, my universe here in the Maritimes is probably pretty similar to yours, but if you ever make it out this way I can guarentee you'll have all the free beer and wine you want 10C :) .

My picture will be worth a 1000 words...

Pascal Sun Feb 20, 2011 12:01 pm

Here is my picture. Hard to get a good quality one.


Howesight Sun Feb 20, 2011 12:08 pm

Hey Pascal:

That little nib on the outside diameter of the ring has gotta go. Your feeler guage is not measuring it, I suspect. Use a good quality ring file.

Pascal Mon Feb 21, 2011 9:17 am

I asked the company I bought my piston and liners from if they were in fact Hastings rings and they said they were either Hastings or Grant rings. They go back and forth between the two dependign on availability. Can anyone tell what brand these are? Thanks


Zero419 Mon Feb 21, 2011 9:26 am

I had the same kit.
Not sure on the ring brand.
I was told they cam wit Hastings, then I ruined them by spiraling them on and off.
I ended up buying new Hastings.
I hope you are using ring pliers to get them on and off and you are not spiraling them on and off.
You need to scrub those pistons and cylinders.
10cent hooked me up with the method.
From memory I think it went:
-soap and water
-WD-40 with clean shop towels until the shop towel comes out clean.

Pascal Mon Feb 21, 2011 6:48 pm

hero419 wrote: I ended up buying new Hastings.

Do you remember if they looked like the ones that came with your original kit. I was looking at your engine build thread and noticed that the rings that came with your kit look just like mine. The reason I ask is I've read nothing but good things about Hasting rings, but a few critical things about the Grant rings. I know I'm supposed to take these things apart and inspect and make things right if they are not, but I have Deves rings and Goetes rings and they were perfect, no touching up needed. That top compression ring gap that came with the AA pistons were not square, and there are burs on each end of the ring that face the gap, from where they were filed. Also the top and bottom surface of the top compression ring has the machining marks in them, kind of like a brushed metal finish. I can only think that this would wear the ring lands out as they move in and out of the lands. The Deves and Goetes top rings were smooth in comparison.

tencentlife Mon Feb 21, 2011 6:55 pm

That is a chrome top ring, looks the same as Hasting's but I don't know what comes with Grants.

Pascal Mon Feb 21, 2011 7:15 pm

Here is a closer view of the top ring showing the machining marks.



Tencent, are the chrome rings shiny when new? I have a slightly used set of rings and the top ring was very shiny. This one is not shiny at all. I know it's not aluminum but it look just like brushed aluminum. Thanks

tencentlife Mon Feb 21, 2011 7:31 pm

That's how they look.

morymob Tue Feb 22, 2011 6:52 am

Gotta do search later but somewhere recently i heard Grant now owned by Cofab, if so might explain some quality issues.



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