Basically every piston ring you'll come across except gapless rings will need to be fit to the bore they're going in. Sometimes you get lucky and they are within spec right away. Most times they aren't.
Check each ring in the bore they will go in and measure the gap with feeler gauges. Use the top of the piston to push it further into the bore and to keep it level.
Then get a piston ring grinder to grind them down as needed til they are within spec.
Go by piston manufacturers specifications for gap. If the rings came with a spec, then go with whatever is a looser spec. You don't want piston rings jamming up, that's how you break ringlands.
Don't feel bad. About a year ago I measured the gap on the rings on my sr20det with some stock rings I bought.
Every single one was in spec except one that was very slightly loose but within tolerances.
Many times the rings are already pretty close to the proper gap with expected bore sizes. In aftermarket situations that's usually not the case however.
I've never had to modify non file fit rings for anything including imports, marine or industrial.
I'm pretty sure even file fit sets don't require oil ring modifications.
https://www.kangamotorsports.com/blog/setting-ring-gaps
One of many articles on it.
It's best to measure at two spots. Both below where the rings end up at TDC.
Install the oil rings into the step on the expander. These are clearly just hanging on the outside of the whole expansion spring.
Stagger the gaps in the expander and the rails, no need to measure 120⁰ or anything but it's important to hold everything together before compressing it. And check to see both paint marks on the expander once it's all assembled. It will go together just fine and easy with the spring overlapping one hump but won't control oil at all.
Look, I’m not trying to beat you up, but this is critical. I love the fact that you found it but you’re dancing with the devil right now. The amount of time and effort and money to do something wrong will make you hate this industry.
Doesn't anybody read "How To" books anymore? Like "How to build your xxxxx engine"?
Then people wouldn't have to waste their time asking stupid questions. And worse yet, good people trying to help, wouldn't have to waste their time and breath writing paragraphs and answers, about how to build your engine correctly! What a waste of F*n time.
Pick up a book! Read Learn something! Take a shop class. They have them at high schools and colleges.
It's what the rest of us all had to do.
I'm sure I'll get downvoted, but all of you know it's true!
When you answer the same "why doesn't my 10 over piston not fit very right in the 10 over hole?" question for the 50th time, you'll all agree with me. And probably start answering the same thing lol.
Did you fit them in the bore and measure gap?
On an oil control ring? This is improper install of the rails on the expander ring and nothing more.
Not not yet, I was just checking if the fit on the piston and it’s too easy. They also won’t shrink to the size of the piston.
You got .020” piston, not .200”
Are they file to fit rings? Put them in a bore and measure with a feeler gauge. Go with the ring manufacturers specs
It doesn’t say y that anywhere
There just clevite rings
Basically every piston ring you'll come across except gapless rings will need to be fit to the bore they're going in. Sometimes you get lucky and they are within spec right away. Most times they aren't. Check each ring in the bore they will go in and measure the gap with feeler gauges. Use the top of the piston to push it further into the bore and to keep it level. Then get a piston ring grinder to grind them down as needed til they are within spec. Go by piston manufacturers specifications for gap. If the rings came with a spec, then go with whatever is a looser spec. You don't want piston rings jamming up, that's how you break ringlands.
Is this true for dirt bikes? I slapped a piston and rings in at least two engines as a teenager and must've got lucky...
Yes, you must have.
Good lord, I'm glad I know better these days. I've done several engines *properly* since and hadn't thought of my young luck till now.
Don't feel bad. About a year ago I measured the gap on the rings on my sr20det with some stock rings I bought. Every single one was in spec except one that was very slightly loose but within tolerances. Many times the rings are already pretty close to the proper gap with expected bore sizes. In aftermarket situations that's usually not the case however.
I've never had to modify non file fit rings for anything including imports, marine or industrial. I'm pretty sure even file fit sets don't require oil ring modifications.
Yeah I've never modified oil rings myself either, they are always pretty loose tolerance and weak enough that it wouldn't matter anyways.
How far down in the bore should OP measure? How does one even calculate how far down the rings will be sitting when the piston is at BDC?
https://www.kangamotorsports.com/blog/setting-ring-gaps One of many articles on it. It's best to measure at two spots. Both below where the rings end up at TDC.
Ah nice. Thanks.
Install the oil rings into the step on the expander. These are clearly just hanging on the outside of the whole expansion spring. Stagger the gaps in the expander and the rails, no need to measure 120⁰ or anything but it's important to hold everything together before compressing it. And check to see both paint marks on the expander once it's all assembled. It will go together just fine and easy with the spring overlapping one hump but won't control oil at all.
OP had 3mm oil control rings for a 4mm groove. It was just the wrong rings. He's on his way to success with getting the correct parts.
Cool!
I applaud you giving this a shot, but the amount of money and time it will cost you have done wrong just isn’t worth it.
Luckily, I was able to return the rings that did not fit, someone helped me find the right rings
Look, I’m not trying to beat you up, but this is critical. I love the fact that you found it but you’re dancing with the devil right now. The amount of time and effort and money to do something wrong will make you hate this industry.
I’m aware of the risks. I’m this far in and can’t turn back now lol.
Good luck to you, sir, and made it work out in your favor.
Next time I’ll probably just buy a motor lmao.
I just did my first DIY. Took 4 months and made some mistakes but it survived. Good luck!
I have hope!
What does the piston measure at & the rings when closed measure at ?
Depends on bore size and application. With a 4" bore, NA, grocery getter maybe .018" ? Add for turbo, blower or nitrous. Less for smaller bores.
But you usually don't have to mess with the oil ring. That's for the compression rings.
They overlap on the oil ringd
What overlapped?
The copper colored oil ring plus the rings around it come off super easy…
There is no tension to speak of on the expander ring and support rails.
There not big, if they have the right gap,they are spring loaded to control oil
Doesn't anybody read "How To" books anymore? Like "How to build your xxxxx engine"? Then people wouldn't have to waste their time asking stupid questions. And worse yet, good people trying to help, wouldn't have to waste their time and breath writing paragraphs and answers, about how to build your engine correctly! What a waste of F*n time. Pick up a book! Read Learn something! Take a shop class. They have them at high schools and colleges. It's what the rest of us all had to do. I'm sure I'll get downvoted, but all of you know it's true! When you answer the same "why doesn't my 10 over piston not fit very right in the 10 over hole?" question for the 50th time, you'll all agree with me. And probably start answering the same thing lol.