A little advice on ring gaps and assembly lube

[steve cowan]

.018 top ring; .025 second ring. Use a good assembly lube on bearings and wd 40 on rings. Any questions on ring lube go to total seal web sight.

hi Steve316,
that second ring gap is a hair bigger than i have ever used myself
care to share your speed secret ( compression ring flutter at hi rpm ??.let a little oil past to help seal the top ring ??)

[Olds455]

Why is everybody so against the use of synthetic oil? That's factory fill for many, many vehicles for multiple manufacturers. If it's so bad, why don't they all do the initial fills with Dino oil and demand that owners not use synthetic until a specified point? They use it from the moment the engine is assembled and nary a single problem due to using synthetic oil from mile 0. So why the big push to not use synthetic oil? Same reason you guys are so stuck on 70s technology?

[cjperformance]

Why is everybody so against the use of synthetic oil? That's factory fill for many, many vehicles for multiple manufacturers. If it's so bad, why don't they all do the initial fills with Dino oil and demand that owners not use synthetic until a specified point? They use it from the moment the engine is assembled and nary a single problem due to using synthetic oil from mile 0. So why the big push to not use synthetic oil? Same reason you guys are so stuck on 70s technology?

I can absolutely tell you that after experimenting on my own engines that assembling one bank after 'dipping' 4 piston assemblies in synthetic 5/40 penrite oil and just adding a smear of mineral penrite 15/40 'running in' oil on the other 4, then doing the 1st 1000km on Delo400 15/40 that all pistons and bores look just the same ! Amazing!

[benno318]

we all have different stories to share regarding synthetic oil and bedding in. im not saying anyone is wrong or right, i read all posts with interest.

ill share a story from one of my customers, i do some machine work for him but he does all his own assembly and will just bottle brush hone at his place. little isuzu g161, its a race series all using the same cars, he had a road car that was the same also, and used to run in his race engine in that car if he couldnt make it to the track with the race car to put laps on it. he would freshen it once a year prior to the new season.

one year after a big thrash getting it all ready, he added engine oil at about 3am and was so tired he didnt realise it was the race synthetic oil, not the run in mineral oil. after a few days running around, the engine didnt feel right (he had been racing these things well over ten years so knew them backwards) and was down about 15psi compression per pot. then discovered the wrong oil was added, tried to run it harder with no success, so bit the bullet, pulled it out, re-honed it, new rings (same brand) and got the power and compression back doing the same thing the next week but with the mineral oil. won lots of races and if i recall, another championship that year.

a few years after that he did another freshen, put the engine straight into the race car and did a days practice. i was there also and it rained all day, i too was running in an engine in my own (different class) race car and found the rain to be good conditions for my running in, however his car just spun the wheels everywhere and he told me he simply couldnt load it up like normal if it was dry - he was noticably down on pace that weekend and said he thought it was due to the run in process.

these little things run a stock type piston with 2mm plain old cast iron compression rings - i wonder if that, and perhaps the ball hone, is why it is so sensitive compared to modern stuff??
i mean, i use chrome rings in some stuff and if it ever comes back apart, the contact area is tiny on the barrel shaped friction surface, compared to old thick rings.

[steve316]

I run .025 on second ring to help keep pressure build up down as not to unload top ring.

[steve cowan]

I run .025 on second ring to help keep pressure build up down as not to unload top ring.

Thanks for the follow up
I figured it was for ring flutter control

[n2omike]

I like to use 2-cycle oil on the pistons/rings/cylinders. It's designed to burn away cleanly. It's also designed to properly lube things, even when diluted 50:1!

[65dragster]

Update. I found a slight nick in #1 cylinder wall, maybe 1/3 down from top. It is enough to catch a finger nail. The bore-hone is fresh. Not sure what happened or whether to address it. I can post pics, if it is helpful. Run it or take back to machine shop to do another light hone? Thoughts?

[steve316]

Any nicks that would catch ring or piston as passed over it needs to be taken care of.

[65dragster]

Steve, is there something I can do to manually dress the nick or does it need to be re-honed?

[engineguyBill]

Jamie,
A nick that you can feel with a fingernail can be an issue. I would have your machinist look at the block and see what he says.

[Keith Morganstein]

Update. I found a slight nick in #1 cylinder wall, maybe 1/3 down from top. It is enough to catch a finger nail. The bore-hone is fresh. Not sure what happened or whether to address it. I can post pics, if it is helpful. Run it or take back to machine shop to do another light hone? Thoughts?

It depends if the nick is below the surface or has a raised edge. If entirely below the surface, it’s not going to cause an issue.
If it has a raised edge that will catch the ring and scrape the piston, it’s an issue.

Look at it with magnification. Try to determine if it’s raised. You could take a piece of piston ring, holding the face against the wall and see if that catches the nick. You can probably debur it if it’s raised, very carefully with a small sharp curved tool or a small stone. Or just a couple passes with a hone.