Je piston ring gap?

[Neffets]

I have a couple of 90mm Je pistons 9.5:1 that have 1,5-1,5-4mm groves in them for the Carerra piston rings.
But do I use JE spec for end gap or OEM ? Nikasil cylinders with 0,004" clearance.

[Neffets]

Its a NA motor with carbs, there is a big difference in JE vs OEM, Je states min 0.4mm end gap on 1.ring, but OEM says 0.1mm. But I guess JE spec is for iron cylinders

[Mark Henry]

Have you tried them in a jug yet?
Likely you won't have to touch them because they're already over OE spec.

[DRACO A5OG]

I have CP Pistons (wedge type) and 98MM (3.8582") Cylinders with CP Ring Set.

I called CP and this is what they stated, use their recommended specs and it must be convert to inches to get the proper gaps:

Top
3.8582 X 0.0045 = 0.017" Gap

2nd
0.004"-0.008" wider than Top Gap, Tech recommended by 0.005" = 0.022" Gap

Oil ring retainer rings
NIB 0.010" minimum is 0.015", No calculating, just need to grind them to be a minimum gap of 0.015" or bit more will not hurt.

Question, how in the heck do you grind or file the retainers without bending the crapola out of them? SO freakin thin.

[DRACO A5OG]

Any one have tips on filing down retaining oil rings a literal hair?

[DRACO A5OG]

Yes, I used my piston with a ring on it and insured they are square on the other side as well.

Thanks for the reply :-D

[Jameel]

Originally Posted by DRACO A5OG

Any one have tips on filing down retaining oil rings a literal hair?

I used one of these, borrowed from a friend. https://www.summitracing.com/parts/sme-906000/overview/

I think I could do it by hand by pinching the ring between two small blocks of wood to immobilize it (or sliding it in a kerf in the block, which would be better) letting perhaps 1/16" protrude out the end, then file the end with a diamond honing stick, like for sharpening pocket knives. That's what the wheel on the commercial tool above has on it.

[DRACO A5OG]

Doh, I almost bought that one. I go the other cranked one, the wheel is so course, I can see it just snag the retainers, for that matter the other two rings as well :-(

[Andy@Altitude]

I pulled my motor this winter and found a hole in #6 cylinder and scoring on all cylinders and scuffed cylinder skits. This is a 3.5l turbo motor, 8.5CR, GT2 EVO cams. JE pistons and Nickies. Max boost set to 10-12psi. Less than 8,000 miles on the motor. After a few weeks of a long WTF moment I discovered the top ring from JE was gapped at 0.0130-0.015. This is what caused motor failure and $5,000 or replacement parts and alot of hours (not to mention the mess of cleaning dirty oil out of all coolers and oil lines) .

I had prior always used Mahle PC sets so never checked ring gaps. Turbo motors must have a larger gap , on my 100mm bores should be .022. JE does not go out of it's way to tell you this, BEWARE THESE FEW THOUSANDS MAKE A BIG DIFFERENCE AND WILL ABSOLUTELY CAUSE PREMATURE ENGINE FAILURE!!

[Mark Henry]

Ummm... every set of JE's I've received from LN has instructions included, instructing you to check the ring gap and has the formula to figure out your ring gap. Similar instructions come with Gotze rings, Deves, Hastings. I don't care who built them, P&C, CR. crank, rods, etc., I check every measurement.
I've build many engines, I never skip doing a ring gap check.

I've also run smaller than recommended (by ring manufacturer) with consulting Charles at LN with no issues, .015 is a bit small, but I'd also be looking at timing and/or AFR issues.
Often the result is not the cause.

[prschmn]

Andy, If you could still measure the top ring gap isn't that telling me it didn't break? They don't tolerate losing there gap for long. I'd agree with mark that you likely have a timing or lean problem.
I think it's important to realize that reccomended gaps all seem to be geared to iron cylinders and keep in mind that Al cylinders expand at about three times the rate of steel-hence the cylinder increases in diameter a ton more so smaller gaps can be used.
And that's why factory gaps specd from Porsche are so much less.