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Gapping Piston Rings
https://www.ausmini.com/forums/viewtopic.php?f=2&t=62761		 Page 1 of 2
Author:  jester99 [ Wed Apr 28, 2010 10:13 pm ]
Post subject:  Gapping Piston Rings
when gapping piston rings, is it ok to file them with a small fine file?

or should i be using the proper grinding tool to ensure the filing i make is perfectly square?

what is you opinion on these piston rings? they are to suit 68mm hillman imp pistons. they look like an older type design as they dont have any beveled edges or anything. not that i would konw much about this stuff, i am an amatuer :lol:

i am told they are about 10 years old and have been shelved all that time. they are wrapped in wax paper with trico maxigrove written on the packaging. anyone know of this brand or had experience with them?

the rings are not marked in anyway, does it matter which way they are fitted on the piston?

Image

i have just been reading alot about piston rings and wanted to ask a few questions.
Author:  Tombo [ Wed Apr 28, 2010 10:23 pm ]
Post subject: 
I have used a fine small file on mine no problems, they are soft so go gently.

I reccomend soft jaws in the vice you use (a bit of aluminium plate with a 90 degree bend) to protect the rings.

They look like compression rings to me, no ridges or chamfer, so they go at the top of the piston and have no right way up.

Make sure there is no muck left on them from the tape :wink:
Author:  jester99 [ Thu May 13, 2010 8:48 pm ]
Post subject: 
Ok so i have measured a few of the compression rings, having found 5 of them are 8 thou without having to touch them.

the rest are much smaller than this and require filing.

couple of questions, and i will file them carefully by hand with a hand file.

i have read graham russel suggests about 9-10 thu gap so this is my target gap. do they all need to be the same, or can they vary a thou of two?

for example can they be 8-10 thou, some at 8 and some at 10 or do they all need to be a set amount?

i had a new set of oil rings arrive this week as the origonal set were cast and were the incorrect size. the new set are the 3 peice type and are not cast.

do i gap all of these aswell? some have a slight burr on the tip of the ring, do i file this off and make the ends smooth?

thanks in advance 8)
Author:  jester99 [ Thu May 13, 2010 8:57 pm ]
Post subject: 
Correction, they are 4 peice rings. :lol:

Here is a couple of pics.

Image

Image

Image
Author:  Tombo [ Thu May 13, 2010 9:27 pm ]
Post subject: 
No harm in checking the oil rings (just the flat ones) but they will probably have ample gap but thats fine. Main thing here is the gap is not tight, big is ok, just offset the gaps on them when assembling :wink:
Author:  niffty64 [ Thu May 13, 2010 10:41 pm ]
Post subject: 
A local mechanic here in mildura sourced these rings for me just recently. check out the repco packaging must have been waiting on the shelve for years.
I had to file the gap. The method i used was clamp the file in the vice.
hold the rings square and rub against file

check in bore with feeler gauge

file the end
check in bore with feeler gauge

file the end
check in bore with feeler gauge

keep going until you have somewhere between .006" to .010"

Image
Author:  david rosenthal [ Thu May 13, 2010 11:18 pm ]
Post subject: 
from the last pic it looks like the rings on the right are top and second compression rings. the ones on the left the thicker ones are a cast type oil ring and the others are 4 piece oil rings. how many grooves does the pistons have.
When I do ring gaps I lay the ring on a flat surface with the gap just over the edge and gently file the gap. Do not clamp them in a vice even with soft jaws because they are very brittle ,only cast iron and if the jaws are not dead flat they can crack when tightened.
Author:  jester99 [ Sun May 16, 2010 7:38 pm ]
Post subject: 
ok gapped all the rings, they are all within 8-10 thou on the compression rings. most are 10 thou. pretty happy with the result.

the square edged oil ring, the one shaped octagonal, does not fit though. i fitted the zigzag oil ring and upper and lower oil rings fine, but this other ring will not fit any way i try it.

i did ask for 3 peice oil rings, and the supplier said they are 3 peice but arrived as 4 peice. i double checked the old oil rings and they are 3 piece so i have installed them as a 3 peice type and they fit sweet. i also checked the gaps on these to make sure they were ok.

any ideas on the 4th ring?
Author:  justincase42 [ Sun May 16, 2010 7:48 pm ]
Post subject: 
You need to install the 4th ring (rail spacer) or else you will have oil squirting out of your exhaust (Learnt this the hard way!).. The 7 sided ring needs to go into the oil ring slot first, then the upper and lower rings, then the centre oil ring.
Author:  jester99 [ Sun May 16, 2010 7:55 pm ]
Post subject: 
they just dont seem to be the right ones then maybe?

if i fit that 7 sided one first, i can fit only one of the flat oil rings and there is not enough gap to squeeze another in.

plus when this 7 sided ring is on the piston on its own, the gap is like the ring is to small, it has a gap of like 10mm. also if i fit the zigzag ring over this 7 sided ring, it then sticks outside of the piston diameter.

i must be doing something wrong or these are the wrong rings.
Author:  justincase42 [ Sun May 16, 2010 8:02 pm ]
Post subject: 
What pistons are you using, do you know the brand? Are they brand new or are you using second hand ones?

When you compress the rings with a ring compressor, the oil ring and oil spacer will compress down to fit into bore.

You have said that you can only fit one of the oil rings with the oil spacer installed. This doesn't sound right and they may have given you the incorrect rings for the pistons your using. You should be able to fit both upper and lower oil rigs, rail spacer and oil ring.
Author:  justincase42 [ Sun May 16, 2010 8:23 pm ]
Post subject: 
I just read your thread in relation to the story behind the rings. So you ended up using the old pistons with the new rings. Were the old rings 3 piece or 4 piece? JP Pistons could be the only place that can supply rings now. I don't think there is anywhere O/S that supply imp rings these days as they all get them from JP.
Author:  drmini in aust [ Sun May 16, 2010 10:51 pm ]
Post subject: 
Original Imp pistons used a cast iron 1 piece slotted oil ring with an expander behind it.
It may be that the ring grooves are not deep enough for your expander spring. But as said above if you don't fit it, she'll be an oil pumper... :wink:
Author:  justincase42 [ Sun May 16, 2010 10:58 pm ]
Post subject: 
Based on what Dr Mini in Aust has just said, you will have to either get new pistons and rings, or get your pistons machined to get the rings to fit. When I ordered a set of B series Pistons from JP, they had to machine the oil ring groove and make it wider before they sent them to me.
Author:  niffty64 [ Mon May 17, 2010 9:05 am ]
Post subject: 
the set i, got also had a 4 piece oil ring set. i check with the mechanic and he advised me to just install the oil ring and side spacers. just the same as the originals.
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