I'm doing my first engine rebuild, thus far nothing appears to be going right. I'm about to gap my piston rings and am wondering if I have to gap the wave ring that sits between the oil rings? I'm unsure on this and I can't find anything about it even on youtube. It seem way to tight for thermal expansion in my eye's..... I'm very leary about proceeding
Pistons I'm running are NPR cast .20 over bore

You must be logged in to view this image or video.

Not to mention the fact the humidities so high my blocks rusting faster then I can build it.
Pics of cylinder 4 12 hours of sitting in my garage after preping for assembly.

You must be logged in to view this image or video.

Also wondering if the stock ring gap specs are what I should be following? (I assume so...)
Standard value:

No. 1 0.25-0.40 mm (.0098-.0157 in.)
No.2 0.20-0.35 mm (.0079-.0138 in.)
Oil 0.20-0.70 mm (.0079-.0276 in.)

Limit:
No. 1, No.2 0.8 mm (.031 in.)
Oil 1.0 mm (.039 in.)

Spray the cylinders with wd40 bro or use some assembly lube and whip the walls down. Once you get rid of that surface rust of course. The ends of the wave ring sit together or over lap if I'm remembering correctly.

I've been rubbing everything down with engine oil, cylinder 4's the only one I haven't been able to get out yet.... its scaring me.
Also been working on piston ring gaps.......!
Top rings are 0.40-0.43
bottoms are between 0. 635-0.64mm
Oil rings ****
right out the box the npr rings are way to big... so next I guess I have to check piston to cylinder wall clearences. No wonder the machine shop "forgot" to write the specs down for me, never going back there.

No they do not over lap!!!! They face each other, as to blend in.

Thermal expansion takes places above the second compression ring, the rings below are for keeping oil from entering the combustion .

And those gap numbers are way too high. Even if you misplaced the decimal point.
You need tools to measure bore and piston diameter, other wise your doing this Honda style....(blind).

You either have the wrong rings or doing something wonky.
You are inserting them in the bore to measure end gap right?

yup I'm putting the rings in the cylinder bore using a piston to make sure the rings square then measuring from there..... I'm getting very frustrated. The piston ring are correct .50 engraved right onto them. Pistons fit like their supposed to clearance is correct there. And the piston ring packs were all sealed unopened....infect the shop said they didn't want to gap the rings for me.... which was weird.
I'll post some pictures of the first and second ring in bore so you can all visually see exactly what I'm talking about.

You must be logged in to view this image or video.

You must be logged in to view this image or video.

Hard to see but the feeler gauge in the pic is .010 inch/.254 mm which is like throwing a sausage down a hallway

miliman13 said:

And those gap numbers are way too high. Even if you misplaced the decimal point.
You need tools to measure bore and piston diameter, other wise your doing this Honda style....(blind).

Click to expand...

I agree, I have tomorrow off so I might just bring the block back into town and go to the only other machine shop we have and see if they can get me the measurements. I've had hit and miss luck with the one I've been using, I was super pissed off when they didn't write down the main, bore and piston gap specs like I asked them to have for me plus they threw out my mint 85mm stock turbo pistons I was swapping out. I just really hoped to have this whole job finished by tuesday and at lest be half way through break in.

You can use a flex hone to clean it out or maybe some rust remover stuff. The flex hone will clean it up without taking material off. Works really well to deglaze cylinder walls and make fresh cross hatch.

1) I would use the stock ring gap specs
2) No, the oil ring is NOT overlapped
3) The ring gap is checked further down in the bore below the ring ridge (not at the top of the bore like in your pictures). I assume you know this, and your pictures were just for show.
4) If the cylinder walls have an adequate amount of oil on them, they will not rust. The only way rust occurs is when moisture meets bare metal...So, you need more oil.

Here's some of the best info you'll find on ring installation. Obviously the specs will not apply to you, but the installation procedure can be used:
http://www.rosspistons.com/information/racing_rings_installation.pdf

Also, see here:

I pushed rings down 2 inches into the bore and still got the same measurements........
I can't even find the receipt for the machine work any more either so this whole build is garbage, I'm going to have to save up again and start from scratch.

I think 0.016 is the allowed max OEM gap.
You may be able to get away with it
I'll double check in a bit.

Dude, first thing you need to do is measure those bores. The receipt wouldn't matter anyways, since it could say your bore is one size and your actual bore size is completely different. ALWAYS check the machine shop's work.

Measure the bores and report back.

I dont have the tooling to check myself so there's the main problem. I did check the main bearings with plasti gauge and they're all .003 so not tight but not loose either. I guess I'll run it into the city quickly and hope they dont say anything about the rust thats all over my bores... I can't get it out so more then likely I'll have to be honed and cleaned again.

I usually run .020-.022" for the top and .024" for the second ring on engines that will see moderate power.

Tight ring gaps break cast Pistons.

Im at the machine shop right now and went over it with them they say its fine. Told them to get the bore and piston to wall measurements for me and reclean the block. Should hear back shortly....wasted four days off doing nothing tho which pisses me off.

donniekak said:

I usually run .020-.022" for the top and .024" for the second ring on engines that will see moderate power.

Tight ring gaps break cast Pistons.

Click to expand...

buhay6 said:

Im at the machine shop right now and went over it with them they say its fine. Told them to get the bore and piston to wall measurements for me and reclean the block. Should hear back shortly....wasted four days off doing nothing tho which pisses me off.

Click to expand...

Listen to them. A larger just needs larger venting via the pcv system. I always run my gaps on the larger side.

donniekak said:

I usually run .020-.022" for the top and .024" for the second ring on engines that will see moderate power.

Tight ring gaps break cast Pistons.

Click to expand...

ok I trust you I'll just leave my gaps as is and hope for the best when I get the block back tomorrow.
I'm getting the machine shop to completely re-clean my block so then it should just be a matter of throwing it all together tomorrow afternoon. I'm going to see if I can even swap motors tomorrow if I have enough time. Going to finish doing the rest of the prep for the remaining components tonight.

keltalon said:

Listen to them. A larger just needs larger venting via the pcv system. I always run my gaps on the larger side.

Click to expand...

That's one of the reasons I'm pulling my current early gen 7bolt out of service, my PVC system is totally overwhelmed. Even with just 10psi its pumping engine oil into my intake, I have top up my oil every 400km (260miles ish). Along with my crank shaft end playing being extremely questionable with about 1mm of in and out movement she's in very rough shape. I'm one of those people who'd rather save an engine then blow it up

buhay6 said:

I'm getting the machine shop to completely re-clean my block so then it should just be a matter of throwing it all together tomorrow afternoon.

Click to expand...

Hell, I'd have them gap the rings then. They'd probably do it cheap, since the have the proper equipment to do it.

GST with PSI said:

Hell, I'd have them gap the rings then. They'd probably do it cheap, since the have the proper equipment to do it.

Click to expand...

haha well they don't really need to be gapped tho, they're already on the loose side right? I am how ever tempted to say "here's my crank while your at it" and have them just put my rotating assembly together for me.

buhay6 said:

That's one of the reasons I'm pulling my current early gen 7bolt out of service, my PVC system is totally overwhelmed. Even with just 10psi its pumping engine oil into my intake, I have top up my oil every 400km (260miles ish). Along with my crank shaft end playing being extremely questionable with about 1mm of in and out movement she's in very rough shape. I'm one of those people who'd rather save an engine then blow it up

Click to expand...

You missed understood . You did the right thing pulling the old engine , if an engine is worn its not the same as a couple thousand ring end gaps.

donniekak said:

I usually run .020-.022" for the top and .024" for the second ring on engines that will see moderate power.

Tight ring gaps break cast Pistons.

Click to expand...

Those are my exact numbers!!
But I'm on wiseco pistons, not OEM cast pistons.
It's within reason to be loose on the aluminum pistons since it expands more than other metals.
I would not recommend those numbers for cast.

Below are the specs.

You don't gap piston rings due to expansion of the piston, you gap them because the rings themselves expand. If you put to much heat into a ring with a tight gap on a cast piston, the ends will butt together, the ring will buckle, and the ring land will crack off the piston.

So based on your measurements... your fine

I'm definitely looser on the second ring then I'd prefer. Just got back from picking the block up from the machine shop, this time they gave me all my measurements YAY!
Pistons are 3.3660
Cylinder bores are 3.3675
Piston to wall clearance is 0.0015 (little tighter then spec so I'm cool with that)
No.1 Ring .017
No.2 Ring .026

Thanks for posting the factory specs Miliman13 I couldn't find them and my hynes manual is well.....terribly useless.

Thank you all for your knowledge and input it's been much appreciated!

Got another question guys. f***ed up assembly when I was putting the pistons in the bore, rod nicked the crank rod journal and put a mm nick in it (fuel line fell off the rod bolt). what are my options? new crank or can I gently sand down the high points on the nick?

You were supposed to have the crank journal at bdc when installing the piston..........
Pull the crank take it to your machinist and get their opinion.
We can't suggest much with out pictures as well.

Can you catch your fingernail on the nick?