Welcome to the North American Subaru Impreza Owners Club Wednesday December 13, 2017
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
Go Back   NASIOC > NASIOC Technical > Built Motor Discussion

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads. 
Thread Tools Display Modes
Prev Previous Post   Next Post Next
Old 10-17-2010, 05:27 PM   #1
Bad Noodle
Scooby Specialist
Member#: 174442
Join Date: Mar 2008
Chapter/Region: Tri-State
Location: NNJ
2007 SuperWagon
I don't spell well

Default DIY Piston Ring End Gap - No funny tools

Thought I'd share what I've learned here.

So here goes.

- First, figure out what your ring end gap should be. Ring end gap is usually based on bore diameter so do your math. Your top and second ring gap will be different based on what pistons your get. For my manley 100mm pistons my end gaps are:

End gap in In = bore diameter in mm / 25.4 * factor from instructions

Top Ring = 100/25.4*0.0055 = 0.0216"
Second Ring = 100/25.4*0.0035 = 0.0137"

So first thing's first, check what you have:

I keep my bores coated with white lithium grease to prevent them from rusting. Works great. Anyway, wipe off about 2 inches. Don't need to clean it with carb choke cleaner since a little oil film is ok:

Put the ring into the bore at the top and use the piston to push the ring into place about an inch down or whatever your instructions say. You want the ring to be square in the hole. Using this piston I lines up the flat underside with the deck of the block ensuring the rings is square.

Next, insert feeler gauges into the gap at the end of the ring until you have one that just barely holds itself up. This is your starting end gap:

Next, you need to practice grinding rings. So after measuring your top and second ring gap, you will work with the ring that needs the most work. For example, my top ring starting gap was .0175" and I need .0215" so I need to grind off .0030". Since this is the first ring I'm going to be doing, need to do some experimenting first. Set before I try to go for .0215" I'm going to see if I can set .0190" properly and if that works out, then go for .0215".

The file setup look like:

When grinding the rings, grind one side only. Hold them so the flat side rides along the vice and when looking down at the ring, the edge is square to the file. This will insure the end gaps stay square. Also, only grind the ring pulling towards you or file from the outer edge towards the inner edge. Do NOT rub it back and fourth.

Use your left had to push the ring against the file and the right hand to keep the edge square. Keeping the edge square takes a little practice which is why you shouldn't grind off too much at first.

If you do really bad, when you hold the ground end of the ring into the light you will see that you're grinding only part of the face. It will looks something like:

If you're grinding the entire face, but not square, when you check your end gap as you should be doing frequently, you will see that the feeler gauge will slip easily into the inner edge but won't move all the way to the outer edge/bore wall. The error looks like:

If you're doing everything correctly, meaning your end gap is set and your faces are square, the feeler gauge should be inserted so that it touches the bore wall, should be a little snug, enough to hold itself up, and the ground faces should be even on the feeler.

Also, be sure you deburr your edges. You're not going to grind off any extra material, you just want to pull off any shards sticking out. I used a bigger dremel grinding wheel and just pulled it lightly against the edges. You can feel it catch the burrs as it moves, so once you can pull it over the edges smoothly, you're good to go.

This will take a while, so take your time. Just for reference, it took me 4 hours to do my rings working at a even pace. Took me about 2 hours to get the setup right and learn to grind them properly, then another 2 hours to do all the rings.
Bad Noodle is offline   Reply With Quote

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Piston ring end gap advice afmardve Built Motor Discussion 22 10-15-2010 10:40 PM
piston rings...end gap? Mawheaton Normally Aspirated Powertrain 1 02-17-2009 01:43 AM
JE 2618 Pistons Ring gap & valve notches... xbcaraudio Built Motor Discussion 4 04-17-2008 11:23 PM
ej20 arias .020 over pistons ring gap Scooby Rex Built Motor Discussion 5 07-31-2006 12:24 AM
ej20 arias .020 over pistons ring gap Scooby Rex Built Motor Discussion 1 07-26-2006 10:33 AM

All times are GMT -4. The time now is 09:40 PM.

Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2017 Axivo Inc.
Copyright ©1999 - 2017, North American Subaru Impreza Owners Club, Inc.