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Hi guys,
I measured piston ring end-gaps and some were too large, including all the oil rings. I have standard bore diameter. Any advice here ?


Some gaps were significantly over spec, including all the oil rings (yes, I measured them far down in the bore, not at the top).

Too small end-gap is way worse than too large, but have a look at these measurements....


#1 compression ring gaps are averaging around 0.016" which is close enough to spec.

#2 compression ring gaps are averaging around 0.019" which is within spec, but one ring is 0.023" and another is 0.039" ! I tried moving these rings to different cylinders.... and its due to that ring being small, not a large cylinder.

Oil ring end gaps are averaging around 0.037" which is way larger than spec.


'82 - '83 specs are:
#1 spec = 0.0083" - 0.0146"
#2 spec = 0.0067" - 0.0209"
oil ring spec = 0.0079" - 0.0276"


Here's that #2 ring with the really large 0.039" gap, you could drive a bus thru there. The cylinder above shows a normal gap.


I'm happy with all the #1 gaps and and those are the most important, but the oil ring gaps are way over, and a couple #2 ring gaps are way over also. These are a Beck/Arnley ring set 013-3867. I don't think my bores are worn out, the machinist said there wasn't much wear.

How big a problem is this ? Seems like the oil rings may not be that big a deal. Should I buy another set of rings to replace some of the short #2 compression rings ?
Thanks
Hi, I’ve been a machinist for years. Bore out your engine to straighten out block. You shouldn’t have those waves at the top. At least hone it out to straighten out the cylinders. You can hone it 1mm without boring it. (A good machine shop can) don’t waste your time and money. Do it once, do it right. Did you check piston to bore clearance? You can do it at home with a feeler gauge, most likely the oistons are to loose in the bore causing them to rock at the top of the cylinder giving you that wave pattern at the top of your cylinders. Also check the notes for taper. You should check ring gap about 1/2-1 inch down in the bore. If the block is straight you don’t have to check the ring gap at multiple places in the bore. Ring gap is more important at the top of bore than the bottom. You should measure before you buy parts and find out what you really need! Good luck.
 

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Registered
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2 Posts
Hi guys,
I measured piston ring end-gaps and some were too large, including all the oil rings. I have standard bore diameter. Any advice here ?


Some gaps were significantly over spec, including all the oil rings (yes, I measured them far down in the bore, not at the top).

Too small end-gap is way worse than too large, but have a look at these measurements....


#1 compression ring gaps are averaging around 0.016" which is close enough to spec.

#2 compression ring gaps are averaging around 0.019" which is within spec, but one ring is 0.023" and another is 0.039" ! I tried moving these rings to different cylinders.... and its due to that ring being small, not a large cylinder.

Oil ring end gaps are averaging around 0.037" which is way larger than spec.


'82 - '83 specs are:
#1 spec = 0.0083" - 0.0146"
#2 spec = 0.0067" - 0.0209"
oil ring spec = 0.0079" - 0.0276"


Here's that #2 ring with the really large 0.039" gap, you could drive a bus thru there. The cylinder above shows a normal gap.


I'm happy with all the #1 gaps and and those are the most important, but the oil ring gaps are way over, and a couple #2 ring gaps are way over also. These are a Beck/Arnley ring set 013-3867. I don't think my bores are worn out, the machinist said there wasn't much wear.

How big a problem is this ? Seems like the oil rings may not be that big a deal. Should I buy another set of rings to replace some of the short #2 compression rings ?
Thanks
You should recheck your bored for taper and size with a bore gauge. That wave shouldn’t be there. Your pistons are probably to loose in the bore. A good machine shop could hone it to the next size to straighten it out. Take it to a good machine shop. Just looking at it tells me it needs to be bored out.
 
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