{"id":324,"date":"2018-03-11T21:41:17","date_gmt":"2018-03-12T04:41:17","guid":{"rendered":"http:\/\/www.nickpisca.com\/diesel\/?p=324"},"modified":"2018-03-12T12:28:54","modified_gmt":"2018-03-12T19:28:54","slug":"7-3-idi-piston-ring-gap-measurement-custom-grinding-and-proper-installation","status":"publish","type":"post","link":"https:\/\/www.nickpisca.com\/diesel\/engine\/7-3-idi-piston-ring-gap-measurement-custom-grinding-and-proper-installation\/","title":{"rendered":"7.3 IDI Piston Ring Gap Measurement, Custom Grinding, and Proper Installation"},"content":{"rendered":"

Even though my original plan for this\u00a07.3 IDI rebuild<\/a> was quick and dirty, I eventually decided to invest some time, money, and effort into a decent piston ring job.<\/p>\n

Background:<\/em><\/p>\n

If you want to skip to the actual piston ring gapping and grinding, overlook this background section.<\/p>\n

So I got this ’94 7.3 from a guy in The Valley.\u00a0 He claims the engine was recently rebuilt, but I don’t know.\u00a0 The engine had some decent wear, and aside from some sloppy gasket maker and the broken crank bearing, it seemed ok.<\/p>\n

After I extracted the ’94 7.3’s pistons and rods<\/a>, I inspected the existing piston rings:<\/p>\n

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At first glance, they did appear to have very little wear and tear.\u00a0 Compared to my ’88’s rings (not pictured), these ’94’s looked pretty nice.\u00a0 So I thought I could keep these through the rebuild process.<\/p>\n

However, just to make sure they are within spec, I measured all the ring gaps in their respective cylinders.<\/p>\n

Measuring the Ring Gap.<\/em><\/p>\n

Using a Piston Ring Pliers, I removed the existing rings from the piston grooves.\u00a0 I’m trying to be careful, because I’m still operating under the assumption that I’ll reuse the existing rings.<\/p>\n

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I slid each ring one at a time into their respective cylinders and, using an empty cylinder, I pressed down my rings so that they sit further down in the bore.<\/p>\n

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Once the piston ring is situated parallel to the deck and deep into the bore, then a proper ring gap measurement can be obtained.<\/p>\n

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In order to accomplish this measurement, “feeler gauges<\/a>” need to utilized.\u00a0 If you don’t know what this tool is, it’s basically a bunch of thin strips of metal that have their thickness printed on the side.\u00a0 They go down to a few thousandths of an inch, up to approx 0.045″.\u00a0 The user just needs to use trial and error to figure out the best fit in the ring gap.<\/p>\n

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A\"\"<\/a>fter I measured all top-, 2nd-, and oil-ring gaps, I put them in a chart (see image to the right).\u00a0 Just for some comparison, here are the Official Ford Specs on the ring gaps:<\/p>\n

Ring Gap in Bore (Engine Number 598753 and lower):<\/strong><\/p>\n