Thread: ring gap questions
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03-14-2007 09:02 PM #1
ring gap questions
I read that most prefit piston ring sets are undersized by up to +.030. I am
guilty on just slippin the rings on in the past, thinking they were right for the application from the factory. I know now that .016 to .018 is a correct gap to use. Is it true that you can give away 20-30 hp by not checking end gap?
Does any brand offer correct prefit sizeing or is it file fit from now on? Thanks."oohh...thats gonna leave a mark!"
1997 s-10, 357 C.I., 350 turbo, speedpro 11:1,Comp Cam custom grind mech. roller, Canfield heads, 1.6 roller rockers, edelbrock tm-1, holley 750sp, Hooker Headers, MSD, 3K B&M stall, 4:11 gears
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03-14-2007 09:20 PM #2
I don't know about the rest of these guys, but I never assume anything when it comes to building a motor. I measure everything and in the case of pistons and rings, I talk to the manufacturer and get the recommended gaps for the application I'm building. Leave nothing to chance and you'll have no bad encounters.
Just like with cams. NEVER, NEVER purchase a cam based on the information you get on this or any other forum. Many of us can get you close and you can compare cams from grinder to grinder based on the knowledge gained here, but before you lay down your hard-earned green, talk with a tech at the cam grinder, not a tech at summit or jegs.PLANET EARTH, INSANE ASYLUM FOR THE UNIVERSE.
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03-15-2007 06:52 AM #3
Originally Posted by techinspector1
Words of wisdom, Read and Heed!!!!
Assuming anything out of the box is correct can be a very costly assumption. Using Denny's method, it doesnt' take a whole lot of time to verify the ring gap. Same goes for the rest of the engine parts, verify the correct fit before you do the final assembly!!!!Yesterday is history, tomorrow is a mystery, Live for Today!
Carroll Shelby
Learning must be difficult for those who already know it all!!!!
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03-15-2007 07:09 AM #4
I was reading a book on how to balance and blueprint a chevy sb, by Rick Voegelin, but it was a 1988 edition.. so I guess some things never change.
TRW and Sealed Power are stated as the only two who make oversize, .005, file fit sets. I know this still isnt the case. Would anyone like to make a recommendation on who makes quality sets that are affordable. I imagine C & A make them, but I bet they are expensive."oohh...thats gonna leave a mark!"
1997 s-10, 357 C.I., 350 turbo, speedpro 11:1,Comp Cam custom grind mech. roller, Canfield heads, 1.6 roller rockers, edelbrock tm-1, holley 750sp, Hooker Headers, MSD, 3K B&M stall, 4:11 gears
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03-15-2007 08:55 AM #5
This is real elementary stuff and you probably know it already. I sure don't mean to insult you, but make certain that your rings are properly "clocked" (the gaps are properly spaced around the piston and not neatly lined up in a row), and the oil ring spacer gap should be lined up with the piston pin toward the rear of the engine.
Also, make sure your oil rings are installed correctly with the spacer stopper pins facing in.
Take it from somebody who has done it wrong despite having a piece of paper from the navy saying that he is an engine mechanic.
Jim
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03-15-2007 10:40 AM #6
Good stuff guys. I'm printing it and putting it in my home-made assembly manual. I hope thats all right with you guys."oohh...thats gonna leave a mark!"
1997 s-10, 357 C.I., 350 turbo, speedpro 11:1,Comp Cam custom grind mech. roller, Canfield heads, 1.6 roller rockers, edelbrock tm-1, holley 750sp, Hooker Headers, MSD, 3K B&M stall, 4:11 gears
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03-15-2007 12:54 PM #7
Posted by Denny:
"Some racers believe that opening up the 2nd end gap even more (say an additional 10%) can improve overall ring sealing by allowing trapped gases to escape before they blow past the top ring and cause ring flutter at high rpm (say above 5000 to 6000 rpm)."
What's alluded to here is that the rings seal on the bottom of the ring against the flat shelf of the ring land. Blow-by past the cylinder wall/ring face junction of the top ring can cause a pressure build-up between the first and second ring and can apply enough pressure to unseat the top ring off the ring land and eliminate the seal. By allowing a little extra room for these gases to exit past the second ring and into the crankcase, the integrity of the top ring seal at the ring land is assured.PLANET EARTH, INSANE ASYLUM FOR THE UNIVERSE.
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03-15-2007 03:48 PM #8
You know you guys are gonna make me tear my 440 apart again, don't ya!"oohh...thats gonna leave a mark!"
1997 s-10, 357 C.I., 350 turbo, speedpro 11:1,Comp Cam custom grind mech. roller, Canfield heads, 1.6 roller rockers, edelbrock tm-1, holley 750sp, Hooker Headers, MSD, 3K B&M stall, 4:11 gears
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03-15-2007 04:22 PM #9
I run a gapless compression ring, love em. Probably not recomended for daily driver type engines, but it sure works great on the go-fast stuff....Yesterday is history, tomorrow is a mystery, Live for Today!
Carroll Shelby
Learning must be difficult for those who already know it all!!!!
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03-15-2007 04:54 PM #10
Dave how does that work, just curious."oohh...thats gonna leave a mark!"
1997 s-10, 357 C.I., 350 turbo, speedpro 11:1,Comp Cam custom grind mech. roller, Canfield heads, 1.6 roller rockers, edelbrock tm-1, holley 750sp, Hooker Headers, MSD, 3K B&M stall, 4:11 gears
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03-15-2007 05:29 PM #11
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03-15-2007 05:42 PM #12
Hey Dave , I was just being lazy on ya. I went to Total Seal and read up on the gapless setup, works great I suppose, but MAN! they are expensive!"oohh...thats gonna leave a mark!"
1997 s-10, 357 C.I., 350 turbo, speedpro 11:1,Comp Cam custom grind mech. roller, Canfield heads, 1.6 roller rockers, edelbrock tm-1, holley 750sp, Hooker Headers, MSD, 3K B&M stall, 4:11 gears
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03-15-2007 11:30 PM #13
As in, I see no difference on the stick when I change the oil. I'm not paranoid enough to actually measure the amount of oil that goes in and what comes out. I run my motor full throttle all of the time, it's too fun not to. I built it 2 summers ago and it's got 20k miles on it now. I've been running a fairly light oil, 10w30. I switched to 15w40 on the last change because I like the extra EP additives like zinc and phosphate. I almost a quart within the first 1200 by my first oil change. Afterwards, I haven't burned anything.Last edited by 76GMC1500; 03-15-2007 at 11:32 PM.
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03-16-2007 06:46 AM #14
Originally Posted by techinspector1
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03-16-2007 09:41 AM #15
Interesting. Well at this point I'm in favor of testing each bore for taper, trying to nail the .016-.018 for the top ring, adjusting the 2nd ring and run a standard oil (vs. low tension). Unless someone sways me from here, thats how I'll work it for now. I wonder how Eric does his???"oohh...thats gonna leave a mark!"
1997 s-10, 357 C.I., 350 turbo, speedpro 11:1,Comp Cam custom grind mech. roller, Canfield heads, 1.6 roller rockers, edelbrock tm-1, holley 750sp, Hooker Headers, MSD, 3K B&M stall, 4:11 gears
I wanted to complain about this NZ slang business, but I see it was resolved before it mattered. LOL..
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