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Ring gap - should I worry...
This has probably been discussed already but I'm not having much luck with the search function so I'll risk digging it up again...
I have a 3.2 rebuild in progress and I'm setting the ring gap for my brand new 98mm JE pistons/bored and re-plated cylinders. I've got the gap on the compression rings to .015", but when I closely inspected the edge of the ring where I filed it (using one of the less expensive benchtop ring grinders) I noticed that it was not perfectly square. I can rotate a straight edge back and forth slightly and see a bit of a gap towards the inner edge of the ring. One in particular is probably .016" on the inner edge. Should I not worry and leave as is, or try and take them up to .016" and get them square, or spend the $150 and get another set of rings? They started of at .012" which is too tight according to people I checked with and the JE spec. The JE spec sheet says I can go to .017" but most people I talked with recommended .015". Is there any particular secret to getting one of these inexpensive ring grinders to get a nice square edge? https://www.summitracing.com/parts/pro-66785/overview/ Thanks as always for any help/suggestions. Bill |
Doesn't need to be parallel perfection there IMO. Make sure you're setting gap at the tightest point and do your best at being parallel. I use a cutoff wheel in my vice to cut my rings and then hand file/debur manually. I'm usually cutting a lot of material from my rings and the old style manual wheel ring files would take hours. Opinions will vary.
Sent from my SM-N960U using Tapatalk |
Porsche gapped the 82-83 top ring at .008-0.016”
I ran .008-0.009”. No issues.http://forums.pelicanparts.com/uploa...1558392977.jpg |
JE spec is for water cooled engines.
Air cooled cylinders expand more. I followed Porsche’s gaps. Rings from Total Seal showed up, at the min spec. No trimming was needed. |
ring gap
You are ok at that spec.Total Seal rings work well but take longer to seat so leave the non detergent oil in a little longer before doing leakdown test.For reference used motors at 5% or more leakdown the ring gaps are getting close to 1mm which is the wear limit.After 5% the blowby past the rings is preheating the precious oil you need to cool the motor.Ciao Fred
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Now I'm thinking that I should get a new set of rings and not touch them if they are greater than .008"? Bill |
I would follow the maker of the pistons specs , JE knows that the pistons were made for an air cooled porsche . Call them if you are in doubt
stick to the plan |
J.E. recommendation is for a cast iron block...
Mahle ring gap is for a Ductile iron top ring...different materials have different expansion rates...this includes rings. My personal experience is no less than .013 gap on top ring for a 90mm nikasil cylinder. I did a high compression build and saw the beginning of rings butting together. This is for the rings that J.E. and CP supplies. |
I wouldn't worry about slight out-of-squareness on ring ends - not an issue. What is more important is running a slightly larger gap on the second compression ring - this helps reduce oil consumption. Only .002" larger than the top ring gap clearance can make a surprising difference.
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I'll throw this out there, if your gap is too tight, even Nikasil will be damaged (my cylinders were scored after about 5 years of running).
BTDT. I will ALWAYS go looser than tighter, but I am boosted. |
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