Ring Filing?

[BlueShift]

Has anybody on here rebuilt a TDC or installed new rings? I have some questions about the ringset I bought and GM specs.

I test fitted my rings into the bores and am getting something like .015" gap on the top ring and roughly the same on the bottom ring. GM says that spec is .008-.018" on the top ring and like .022"-.032" on the second ring. It's a Sealed Power plain iron ringset with moly face topring for the later year style piston. I was under the impression that they were good to go out of the box, but I'm beginning to wonder about that. Also, my machinist mentioned that Silvolite pistons commonly recommends a wider top ring gap, as the hypereutectic alloy pistons tend to reflect more heat, causing the top ring to get hotter than ordinary cast pistons. I'm using Sealed Power hypereutectic pistons, and am curious if this is a factor here as well?

Be eternally grateful for any pointers, info, etc!

[your_I.D.]

from Summit:

"If you're looking for pistons with an unbeatable combination of performance and value, Speed-Pro hypereutectic pistons are for you. These pistons are manufactured from FM244 aluminum alloy, which contains 16 percent silicon for greater strength and wear resistance. They're also molded in the latest permanent-mold technology to ensure the precise fit and tight bore clearances that today's top engine builders demand. They're ideal for use in high-performance street, bracket racing, and Oval Track, and will work perfectly with normal ring end gaps. "

[BlueShift]

Cross Post From PFF

Some of my findings after taking actual, precise measurements today:

A little more on piston rings and the big, headache inducing, head banging on hardwood desk causing lack of information regarding ring gap on these motors. I took them back off of my pistons (I do everything backwards...) and test fit them in the bore and measured their clearance.
1.) Using a flat top piston as a guide, press the ring (with the top side of the ring up, obviously) into the bore about where it would be at TDC. Make sure it's dead square.

http://img.photobucket.com/albums/v249/pyromaniacal/TDC%20Swap%20Project/Engine%20Rebuild/Assembly/Piston.jpg

http://img.photobucket.com/albums/v249/pyromaniacal/TDC%20Swap%20Project/Engine%20Rebuild/Assembly/Ring_In_Place.jpg

2.) Using a feeler gauge, measure how much end gap is present - consensus seems to be that the best reading is where the gauge slips in just snug enough to barely hold the gauge in place, without excess force required:

http://img.photobucket.com/albums/v249/pyromaniacal/TDC%20Swap%20Project/Engine%20Rebuild/Assembly/Measuring_Gap.jpg

My end gaps with rings straight from the box as measured by a brand new feeler gauge are as follows:

#1 Top: .015" Second: .013"
#2 Top: .014" Second: .013"
#3 Top: .015" Second: .013"
#4 Top: .015" Second: .014"
#5 Top: .015" Second: .013"
#6 Top: .014" Second: .013"

... Ok. GM (96+) spec says .008" - .018" for the top ring, and .022" - .032" (!!!) gap for the second ring. That's a big ass gap, from what I know. My machinist also says that even .024" gap on certain KB hypereutectic pistons is extreme, and .032" is nuts. I called the Federal Mogul tech line and after telling him it was a basically stock rebuild, he said something along the lines of "well um... just put them at GM spec, or something, yeah." Great. The most interesting thing was when I looked up rules of thumb for high performance motor building (SBC's mostly). They say .004" per inch of bore for the top ring, and 80% of the top ring gap for the second ring gap. Guess what that turns out to be? .0146" --> .015" for the top gap! Second gap computes at .01168 --> .012" which is really close to the .013 I'm getting! Are these things already ready to drop in, with performance use gaps already set up? There's no mention of ring gapping on the box, or anywhere. In fact there's no indicator that I should file at all, except for the glaring mismatch between what GM wants and what the second ring is set up at. I'd personally rather not file if I don't have to, but I gladly will if that's what I gotta do.

I'm so incredibly confused that I don't know what to do. I'm not going to take a chance with what has to be one of the most critical components in an internal combustion engine. Can anybody give me a couple pointers here, and perhaps shine some light on the big ring gap mystery? I'm pretty much out of places to ask, my machine shop says stay where they're at, and perhaps file a little on the second ring. Another machine shop (that didn't rebuild the motor) says file them to GM monster gap specs. The rings themselves are perfectly gapped for performance specs that may or may not apply to my engine. I'm totally out of places to ask and have no clue who to believe. Anybody have any ideas? This is the only thing holding me back at the moment.

[BlueShift]

from Summit:

"If you're looking for pistons with an unbeatable combination of performance and value, Speed-Pro hypereutectic pistons are for you. These pistons are manufactured from FM244 aluminum alloy, which contains 16 percent silicon for greater strength and wear resistance. They're also molded in the latest permanent-mold technology to ensure the precise fit and tight bore clearances that today's top engine builders demand. They're ideal for use in high-performance street, bracket racing, and Oval Track, and will work perfectly with normal ring end gaps. "

you_I.D. - My machinist JUST looked up his Sealed Power catalog earlier and found this out, after making me incredibly paranoid. Thanks man!

[your_I.D.]

The only rimg gaps I have ever filed. Were a set of Total Seal rings. I've built in excess of 100 SBC using Seal Power parts. I would just check ring gap to make sure I had the correct set for my over bore on one cylinder. Then assemble it. Never had a ring problem.

[BlueShift]

Another Federal-Mogul/Sealed Power tech today told me that the E928K ringset isn't a file to fit set - that the file fit sets end in 25 or something like that. I'm beginning to think that having verified that the gaps aren't all over the place, that maybe I should just drop them in. I'm still looking for a last word before I commit though.