Thread: ring gap questions

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Originally Posted by jimmyjeep

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???

If you're going to open up the second ring, make the gap 1.5 to 2 times wider than the gap on the top ring. That's what the experts recommend. Also, pay close attention to the procedure used to hone the bores. Here's a blurb from Speed-O-Motive:
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When installing new rings, the single greatest concern is the cylinder wall condition and finish. If the cylinders are not properly prepared, the rings will not be able to perform as designed. The use of a torque plate, head gasket, and corresponding bolts are necessary to simulate the stress that the cylinder head will put on the block. Main bearing caps should also be torqued in place. The correct procedure has three steps. First the cylinder is bored to approximately .003" less than the desired final size. Next it is rough honed within .0005" of the final diameter. Then a finer finish hone is used to produced the desired "plateau" wall texture. Use a 280 - 400 grit stone to finish cylinder walls for Plasma Moly rings.

Note - the "grit" number we are referring to is a measurement of roughness, it is not the manufacturers stone part number (a Sunnen CK-10 automatic hone stone set #JHU-820 is 400 grit). The cylinder bores should be thoroughly scrubbed with soap and hot water and then oiled before piston and ring installation.

Piston ring grooves are also sealing surfaces, and must be clean, smooth and free of defects. Ring side clearance, measured between the ring and the top of the groove, should be between, .001" and .004"."

Jim, I'd also advise you to go with the high side of the spec on top ring gap. If you get a little more gap than you might think you need, it's not going to make a huge difference in the way the motor responds. But if the gap is too tight and the rings end-butt, you are looking at doing the whole thing over again and if the bore is already at max, you're looking at finding another block before you can begin. Err on the side of caution. Be sure and follow the manufacturers instructions to the letter. If they don't give you an end gap figure, get on the phone and nail it down for sure.

first step is TQ the main bolts/studs down this will pull on the bores and i bore with the main TQ down .the way i do it is leave .004 this has alot to do with that kind of block it is as to how out of round the bore will get with the TQ plates . in the bore use sunnen stones 1set roughing to about.002 is left .2step hone medium to.0005.3 fine to 0000. then plateau hone i would add that i do used TQ plates i do use them all most of the time .when i am done a have less then .0005 from top to bottom of the bore this is check with a sunnen bore gauge have be doing them this way it works for me and it takes a day i let the bores cool down they will move from the heat when honing them and if you are cutting your rings and was hone with a QT plate then you should have one on the block when you cut the rings

Pat's got a good proceedure. Torque plates are hard to beat especially when used with temp compensation for round and straight bores.

I worked in the Ford diesel plant for a while and ran the hone that did the 6.0 blocks. One block per minute. The first step is about .0040 from final size, one stroke in and out takes out about .0025. Stage 2 is the medium stones and takes out about .0010. About 15 strokes. The final sizing .0005 puts the final bore finish and size. Held to around .0001/.0002 for all 8 cylinders at a given temp. Cylinders were round and straight within about .0002 as I recall. The machine was nearly 200 feet long and fully computerized. It would do these all night long and not require adjustment. Bore sizes were done with an air gage accurate to .00002 4 zero's with 2!! Temp compensated. Finish was also checked top middle and bottom at the same time and all 8 were the same and to spec or something was wrong and the line shut down. no torque plate but the main girdle was on and torqued. Not bad for a production motor.

It took about 8 hours to get the machine temp stabilized so it was not shut down except for a good reason.

One more thing. For those of you who have wondered what the circumferential groove is that is between the first and second ring land on a piston, it's an accumulator space for gases which have escaped past the first ring to expand and exert less pressure on the underside of the top ring, lessening the chances of unseating the top ring. More volume, less pressure. Pretty cool, huh.

[QUOTE=jimmyjeep]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![/QUOTE

Heck, everything is expensive!!! What's another couple hundred in rings????

What the other guys said on bore finish is very important. Guys like Pat that have a lot of experience with a power hone will do a great job. The guy I use now has a power stroke hone and it does great too. Even a good hone in the hands of a bad operator will give you grief for as long as you have the engine!!! Spending the extra $$$$ to get the right man with the right machine to do your cylinders is money well spent!!!!!