filing piston ring end gap

Paul LeClair

Paul LeClair

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Staff member
Location
Calgary, Alberta, Canada
Hi all

have a new set of "file to fit" piston rings. Before my garage fire I had a litle hand cranked grinding wheel thing that I used to use to set ring end gap.

it really wasn't that great. Don't really want to waste $70 or so on a cheap one, and don't want to spend the several hundred for a good one.

either going to clamp a file in a vice upright and drag the rings across it, or thinking about using a high speed Dremel with a cutting/grinding wheel?

Has anyone got any tips or suggestions? The basic advice always typically seems to be to file from the outer edge of the ring to the inner edge so you don't leave burrs on the outer edge of the ring that contacts the piston wall, and to file the ends square to each other
 
Yep, good quality small file (fine cut) works fine for low volume work. Your last sentence covers exactly the way I used to do it before getting one of those little grinding jiggers and did plenty that way with no issues.
 
clamp the rings in your pich vice with just about 3mm showing and the end sqauer to the jaws, then use the fine cut file as mentioned above, deburr all for edges with emery paper.
cut once measure twice, when its gone it cant be put back.
CLEM
 
1957 Gilera piston has four rings, one piston. Hand filing ring end gap sucks, thankfully only one piston. Clamped a double sided fine file upright in the vice, moved each ring gap against the file, constantly checking resulting gap by inserting ring half way into cylinder bore, using the piston to square the ring up in the bore, checking with feeler gauge. I found the process slow and stressful. I usually like fine detail work, but not this ring end gapping, at all.:rolleyes::rolleyes:(n)(n) Those of you good at this, my hat is off to you!!
 
Yes, correct tangential load is where it is at. And the fit of the roundness/fit of the ring into the bore. I have heard people say that you can get an oversize ring and fit it as long as the end gap is correct, not in my book though. It is reassuring though to see the info from the article that a correct ring is not particularly dependent on end gap.
 
Ditto Paul, a custom made dremel jig, took some little time to design and fabricate properly, though was a tedium remover no question. BTW of custom rings, the gal at Deves is/was no little clever gal, had a "problem" with witness marks on a cylinder bore, 180 early barrel. Had even automotive engineers mystified, while in conversation with Deves gal, she mention back clearance on the piston ring grooves, near zero on the old rings and new ones....solved! Modified a HSS parting tool bit, eased the back clearance to Deves spec, still going... maybe 20 years later... as it may help others with obscure ring issues. j
 
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