I was curious if any of you guys know some of the standard procedures for properly gapping a ring. I have seem some info saying ranging from 4 thousands to 6 thousands per inch of bore. Anyways how critical is it to have the gap absolutly perfect? what if you have it a couple thousands larger than what is suggested?

 

You want the least gap possible. That is short of ever touching each other due to thermal expansion. The less gap help prevents premature future oil usage and excesive blow by. Just gap rings per manufacture suggestion. Or buy pregapped or gapless rings

Always pay attention to the direction on ring gap placement during piston installation.

 

Well I gapped mine to .025 on the top ring, .026 on the second ring on a 4.155 bore. However 2 of my cylinders I ended up with a .028 and a .030 top ring gap. This really pissed me off as I honestly tried very hard to take my time and take it slow. But some how I just took too much off too fast. but at the same time, 5 or 4 thousands looks like absolutly nothing, and I am wondering if it would hinder performance much?

 

Always lots of discussion on ring gapping. GKull is right, you want the least possible without them butting...hence the .004 per inch guidelines.

But a lot depends on what you will be doing. Is Nitrous in the plan? You need to loosen them into the .006 per inch range.

If you are using Hypereutectics, typically they require a much larger than normal gap to keep them from butting due to the extra heat retained in the piston crown area. Same with blowers.

Lots of folks are playing with leaving the second ring looser than normal..meaning a larger gap than the top one. For years it's been the other way around, but current thinking is to allow whatever gets past the top ring to go on by the second a little easier to keep from "unseating" the top ring. While some of your seal is at the edge on the cylinder wall. much of it is actually along the bottom of each ring land. If too much pressure is trapped between the top and second ring it can unseat the top one causing leakage.

You have them a little loose for an unblown, forged piston, no nitrous motor, but it won't kill you. You might try combining your tightest top ring with your loosest second ring to even things out or other way around...whichever you want. You also might try them in different cylinders to maybe help. A little cylinder bore size difference can make a big difference on ring gap.

Pay attention to the ring gap placement. It does make a difference as to which side you palce things with respect to minor and major thrust surfaces. Just use the Gm manual or the instructions in the box.


JIM

 

Thanks for the response, I am going twin turbo. So yes Cylinder pressure will be at a maximum. This really bothers me, I am half way tempted to just pull them out and get another set.

 

the guys have given you good info as far as they went but keep in mind that its better to be a few thousands to large than a few thousands to tight on the ring gap! if the ring ends expand and touch under high cylinder heat and pressure they can and will lock the ring in the cylinder, that can and frequently does pull the top ring land off the piston, with the comon result that those chunks of busted aluminum bounceing around in the cylinder cant be easily compressed, and either a rod, or the cylinder head or both take a tremendous beating and engine failure is the result of the bits of aluminum and steel whipping around at 5000rpm and being slammed into other parts at 40 to 50 times a second with 300 plus foot lbs of tq,thats like useing a sledge hammer on your engine)

http://www.kb-silvolite.com/speclear.htm
http://www.totalseal.com/howdoo.html
http://www.holley.com/HiOctn/ProdLin...IECP/Ring.html
http://www.babcox.com/editorial/ar/ar110060.htm
http://www.axtellsales.com/NewFiles/HowTo/How%20To%20 PDF/Piston%20clearancing%20and%20Ring%20End% 20Gap%20Instructions.pdf
http://www.hastingsinc.com/Service%2...stallation.htm

 

Twin Turbo??? That's important!

I'd probably leave them where they are....as mentioned.....too little is worse than too much. You don't want to take ANY chances with it during the tuning process. Boost will make up for any slight leakage. I don't think you will have any issues.

You might check around with folks that are running a similar intake/head setup and see if there are any particular cylinders that tend to run hotter/leaner than the others. Most engines have a pattern with certain components. You could install the looser rings in that hole and have a little insurance.

JIM

 

Very intresting. Thanks for the responses so far. I also called around and I basically heard that it probabily won't be noticable what so ever. and hardly any noticable HP loss. however it still gets me why they would have such small differences between what a daily driver stock engine would have and a nitro drag engine would have.
So how about this for a question. What would you do if you wanted a gap of .025 and ended up with a gap of .030????

 

The biggest difference is the amount of heat each combination will put into the piston/ring ackage. There has to be more clearance for the increased heat. Under severe operating conditions those larger gaps are likely to close to something pretty close to what the milder combos experience anyway. The more power, the more heat, the more clearance. You have to set it up for worst case scenario. It's all a compromise.

Being you will have twin turbos, you will have lots more heat and potential for problems than a N/A deal. Definitely better to err to the safe side.

I doubt you will see any issues with it. If it really bothers you, you MIGHT be able to get a single ring set for your application and just re-do that one hole. Depends on what rings you have.

Check with local engine builders...they might have a set sitting around where they did the same thing and might be able to sell you enough to make them all perfect.

Are you dead sure the rings are square in the bores when measuring? Just a little "twist" really throws off the measurements. One way is to install the oil rings on a flat top piston and use it to square them with. Just insert inverted piston until oil rings lay on deck and reach in from bottom and make sure ring is pushed square against piston. Remove piston and measure gap.


JIM

 

DANG I didn't think of using a piston with the oil rings. I simply just pushed them down with a new piston. One other point i guess I should bring up is, I don't have a engine rebuild book, and the instructions for the rings didn't state anything in regards to proper clocking of the rings. I went ahead and clocked them to 3 o clock and 9 o clock, then the oil rings have their gaps in between those. any details on the rigt way? so I can go and fix that problem.

 

What brand of rings are you running?? You sure they are good enough for twin turbos? You really have to make sure you don't skimp on rings and pistons on a boosted motor. There WILL likey be some detonation eventually and cheap rings won't take that long.


Check out Sealed Powers web site ..they should have some pictures for you, basically you are putting compression ring gaps at 3 and 9 like you did, but they need to be in the right place. One bank goes on one side, the other bank goes on the other side. The oil rings get staggered a particular way too.

The way you have done it will work, all rings will move during use and rotate around piston. Putting them in the right place to start helps keep them in the right area and not end up with gaps aligning later.

You really need to get a couple of engine books as you get into this deal. They will help...mine are pretty dog eared..I still use them regulary..the mind fades.......


JIM


[Modified by 427Hotrod, 4:06 PM 7/23/2003]

 

I had some books, but felt I had a pretty good grasp over the engine basics, but I just have not really got into the details of the rings.

I am going to really get into the details of the rings. I spoke with 2 more race shops today and they said I should replace them. I asked why and they both said that it's possible now that the combustion flame could travel down past the gap much easier and over heat the second ring and ring land. makes sense to me. But again how in the world would such a small gap create such an issue. By the way they were speed pro's moly rings. I thinking about replacing them all now with some childs & albert stainless conventional ring set. Pisses me off so much though I so want to just get it together and be done with this, pay off my bills and move on.. arg!!!

 

Alright I went with the Childs & Albert Stainless steel file fit ring set. now i want to get one of those handy ring filers so i don't make the same mistake again.