Correct PISTON GAP (part two)

[MandarinaRacing]

Ok, having figured out the most sensible way to position the gaps, a new question arises...
What about gapping the rings....????
Of all the engines I've seen rebuilt I never saw anybody doing this....but all the car mags and experts say that it's a MUST....

First of all I don't have a ring grinder, and I would'nt feel comfortable doing it with a file on a vise

Is this procedure ABSOLUTELY mandatory? For a re-ring job?

Alex

 

[80broncoman]

I belive you should measure your gaps to make sure you got the right rings. One usally has to order rings for file fiting. They are usally not sold
to a customer with out them being told. Also a lot of time can be saved by taking one piston and putting the lower compression ring on it and use it upside down to push the other rings evenly down in the cylinders to measure the gaps.
Jim

 

[MustangSix]

For a daily driven, mild performance 200/250 engine, the ring end gap should be between .011" - .022". You can verify this by inserting a ring into the bore, squaring it up with a piston, and using a feeler gauge to check the gap.

Most good quality ring sets will fall in this range when fitted to the specified bore. Be aware that you cannot file moly rings. Filing causes the moly layer to flake off.

 

[goinbroke2]

There can be alot to this, but not for the street. It depends on gas/alchy/nitro/nitrous/blown/rpm/etc.
Just make sure your second ring has more gap than the top. Why? Because at high rpm the gases leaking past the top ring will build up against the second and go under the first causing ring flutter which can break rings/lands....I'm going too deep again aren't I?
I put the rings 1/3 apart and gap to application. Go by what the spec's call for, you only deviate to suit a specific application.

 

[broncr]

I've only seen the gap being "addressed" once. I was working at a shop and this kid's uncle had a hot 396 Chevelle (12 second quarters). The kid was just 14 and was making sure ALL of the gaps were the same. His dad had an end gap grinder at the shop.

That was also the first time I had seen a head milled so far down that you could see through some of the low spots in the edge casting.

I agree that for most of us it's an issue that we needn't be concerned about . The few times I've checked, it was in the spec range. The ONLY time I'd be concerned is with a worn block that is being honed rather than bored. So in your case, Mandarina (re-ring job), I'd check it, but not be too concerned. If the gaps are that much different, you may have to use oversized rings.

& relax, it's good that you're thinking about these things now, rather
than after the engine is together.
Broncr

 

[MandarinaRacing]

Thanks guys!

From the looks(& feel) of it there doesn't seem to be any wear on the cylinder walls.
Broncr, one question though, my engine pistons are already 0.040" over, so I bought 0.040 over rings part # E219X40 .....did I buy the correct ones???? Is this what you mean by oversize rings?????

Alex

 

[broncr]

Well, I've never had to use them, but my understanding is that rings are available in small increments greater then the standard overbore sizes. I looked into them a couple of years ago before deciding to bore +.060.

Measure your end gap first, then go chasing my phantom if you must... (.041, .042...) I'd be surprised if you weren't in range. "If it will catch a fingernail, bore it"...

Broncr

 

[Falcon62]

I always check ring end gap when assembling an engine, and I normally check it on all cylinders. It's a peace of mind thing. On daily driver engine, I prefer ring end gap to be mid-range or less.

If your bore is .040", then .040" rings are the correct size for your engine.

The only time I used oversized rings was when I reassembled my 428 during a re-ring job. The bore was already at .030", so I bought .035" rings and file fit them to each cylinder.

If you are going to file rings, I highly recommend you buy a ring filer or practice on some cheap rings before you try this on a set you will acutally use.

"If it will catch a fingernail, bore it"...

Absolutely right, and you can't see or feel cylinder taper unless it's really bad.