measuring piston ring gap, too wide?
03-16-2005, 03:09 AM
#1
Junior Member
Thread Starter
Join Date: Jan 2003
Location: Sacramento, CA, usa
Posts: 264
Likes: 0
Received 0 Likes
on
0 Posts
measuring piston ring end gap, too wide?
ok first of all im rebuilding a 94b18c with .25mm oversize jdm itr pistons. Today I was checking the end ring gap and the specs were wider then the specs in my 94gsr helms manual. The specs read (.017-.018) for top ring and (0.025-0.027)for second ring on all four cylinders, but in the manual the specs supose to be 0.008-0.014in for top ring and 0.016-0.022 for second.
My question is, are jdm itr ring end gap specs different? Maybe because its a higher compression motor mean more heat so the wider gaps, rings can expand? Anyone know the specs for the jdm itr or the usdm ring gap specs? If they use same specs are my rings ok with this wider gap? thanks
Modified by HKSone at 12:36 PM 3/16/2005
My question is, are jdm itr ring end gap specs different? Maybe because its a higher compression motor mean more heat so the wider gaps, rings can expand? Anyone know the specs for the jdm itr or the usdm ring gap specs? If they use same specs are my rings ok with this wider gap? thanks
Modified by HKSone at 12:36 PM 3/16/2005
03-16-2005, 06:24 PM
#6
Re: (pontiac power)
Ive found that the OEM rings tend to be on the loose side of spec for the most part. (provided they are infact oversize. like they are supposed to be)
This depends on a number of things like, the quality of the machine work being the main thing.
You may want to try a set of diffrent rings, Hastings rings perhaps, then you can set your own gap.
-s
This depends on a number of things like, the quality of the machine work being the main thing.
You may want to try a set of diffrent rings, Hastings rings perhaps, then you can set your own gap.
-s
03-16-2005, 06:26 PM
#7
Honda-Tech Member
Join Date: Jul 2003
Location: USA
Posts: 2,496
Likes: 0
Received 0 Likes
on
0 Posts
Re: (pontiac power)
You might have to get some different rings that aren't gapped too large already. I had to do this about a week ago. Sometimes the gaps are already too big before filing.
Trending Topics
03-16-2005, 07:41 PM
#9
Honda-Tech Member
Join Date: Jul 2003
Location: USA
Posts: 2,496
Likes: 0
Received 0 Likes
on
0 Posts
Re: (stock93cx)
ideally you qould use a ring filer, they make electric ones and they make hand crank ones. Or you can do the pain in the *** method and less perfect by using a regular file in a vise and filing the gap manually. then you also need to deburr them them, that is get the little micro-shards that are a byproduct of the regular filing. I used a magnifying glass to look at the gap and see the burrs and lightly file them off. 
03-16-2005, 09:16 PM
#10
Honda-Tech Member
Join Date: Jan 2003
Location: Socal
Posts: 1,180
Likes: 0
Received 0 Likes
on
0 Posts
Re: measuring piston ring end gap, too wide? (HKSone)
another question is, Are your bore size right??? machine shop could of bore the sleeve out too big, just by .002 or so. you got to check that too. my rings did not have to be file. fell with in spec. i have the same rings
03-17-2005, 02:55 AM
#11
Junior Member
Thread Starter
Join Date: Jan 2003
Location: Sacramento, CA, usa
Posts: 264
Likes: 0
Received 0 Likes
on
0 Posts
Re: measuring piston ring end gap, too wide? (TRAN)
what tool would i need to measure the bores?but the rings are right it says .25 OS on it, anyone got the jdm or usdm itr ring end gap specs??? I might try different rings but how much are hasting rings and are they reliable as honda rings? thanks
03-17-2005, 05:35 PM
#13
Join Date: Feb 2005
Posts: 106
Likes: 0
Received 0 Likes
on
0 Posts
03-18-2005, 02:19 AM
#14
Junior Member
Thread Starter
Join Date: Jan 2003
Location: Sacramento, CA, usa
Posts: 264
Likes: 0
Received 0 Likes
on
0 Posts
Re: measuring piston ring end gap, too wide? (pontiac power)
it looks like the machine shop overbored my bores .005-.007 inch over the recommended .25mm oversize. 
Anyways what are my options, #1 stay with the current oem rings with them out of spec but their not to their service limit yet or #2 get new aftermarket rings and file them to spec? #3 get aftermarket 81.5 pistons with their rings and get everything rebored with new rings (dont want to take this options because on budget)
pleast help, how much will this wider ring gap effect or bigger bore effect the performance of my motor? thanks
Anyways what are my options, #1 stay with the current oem rings with them out of spec but their not to their service limit yet or #2 get new aftermarket rings and file them to spec? #3 get aftermarket 81.5 pistons with their rings and get everything rebored with new rings (dont want to take this options because on budget)
pleast help, how much will this wider ring gap effect or bigger bore effect the performance of my motor? thanks
03-18-2005, 03:57 PM
#15
Junior Member
Thread Starter
Join Date: Jan 2003
Location: Sacramento, CA, usa
Posts: 264
Likes: 0
Received 0 Likes
on
0 Posts
Re: measuring piston ring end gap, too wide? (HKSone)
What aftermarket rings are reliable as honda or you guys prefer? rjay and sander?? what aftermarket did you guys go with? and do they make it in 81.25mm oversize? i checked hasting ring website and it only shows the standard 81mm bore...
03-18-2005, 06:30 PM
#16
Honda-Tech Member
Re: measuring piston ring end gap, too wide? (HKSone)
I would start with raising cain at the machine shop. They did a bad job of boring out your cylinders, apparently. 
Have you talked to them about it?
Have you talked to them about it?
03-19-2005, 06:22 PM
#17
Junior Member
Thread Starter
Join Date: Jan 2003
Location: Sacramento, CA, usa
Posts: 264
Likes: 0
Received 0 Likes
on
0 Posts
Re: measuring piston ring end gap, too wide? (drdisco69)
nope i haven't but hey i need to know which aftermarket rings should i go with? and maybe they could pay for it...
03-19-2005, 06:49 PM
#18
Honda-Tech Member
Join Date: Mar 2003
Location: Hudson, NH, 03051
Posts: 3,333
Likes: 0
Received 0 Likes
on
0 Posts
Re: measuring piston ring end gap, too wide? (HKSone)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HKSone »</TD></TR><TR><TD CLASS="quote">it looks like the machine shop overbored my bores .005-.007 inch over the recommended .25mm oversize. </TD></TR></TABLE>
If the bores are really .005"-.007" over the plus .25mm(.010") the rings are the least of your problems .The piston skirts will break right off.I hope you (they) mean .0005"-.0007".
If it was my own engine I would run them as they are.The biggest problem is not having enough gap.If it was a customer engine I would give it a try with JE or CP ring.And they are what I usually start with.
Glenn
</TD></TR></TABLE> If the bores are really .005"-.007" over the plus .25mm(.010") the rings are the least of your problems .The piston skirts will break right off.I hope you (they) mean .0005"-.0007".
If it was my own engine I would run them as they are.The biggest problem is not having enough gap.If it was a customer engine I would give it a try with JE or CP ring.And they are what I usually start with.
Glenn
03-21-2005, 01:07 AM
#19
Junior Member
Thread Starter
Join Date: Jan 2003
Location: Sacramento, CA, usa
Posts: 264
Likes: 0
Received 0 Likes
on
0 Posts
Re: measuring piston ring end gap, too wide? (NJIN BUILDR)
according to the measurements from the piston rings it looks like its about 0.005 too big. I'm sorry i'm not sure what you mean, so you're saying the .005 larger bore will break my piston skirt? please read the first post, i have the ring measurements....Do CP have rings for .25mm oversise itr pistons? If you're saying it would break my piston skirt, then i would need to rebore my setup and get .5 oversize to fix the problem?
03-21-2005, 04:51 AM
#20
Honda-Tech Member
iTrader: (3)
Join Date: Jan 2000
Location: Bloomington, IN, USA
Posts: 10,180
Likes: 0
Received 3 Likes
on
3 Posts
Re: measuring piston ring end gap, too wide? (HKSone)
My piston-to-cylinder wall clearances are around .0022" to .0023" and my top ring end gap is .014" to .015", and the 2nd ring end gap is .024" to .025". JDM ITR .25mmOS pistons and OEM Honda .25OS rings.
I'd have the bore size remeasured again as well as the piston-to-cylinder wall clearance if you're really worried about running too loose.
Personally, I think the clearances are a little on the loose side, but still usable. Your oil consumption shouldn't change that much with that small of a difference in end gap specification.
I'd have the bore size remeasured again as well as the piston-to-cylinder wall clearance if you're really worried about running too loose.
Personally, I think the clearances are a little on the loose side, but still usable. Your oil consumption shouldn't change that much with that small of a difference in end gap specification.
03-21-2005, 03:46 PM
#23
Junior Member
Thread Starter
Join Date: Jan 2003
Location: Sacramento, CA, usa
Posts: 264
Likes: 0
Received 0 Likes
on
0 Posts
Re: measuring piston ring end gap, too wide? (drdisco69)
i'm sure the bores are at least .005 too big,so it shouldn't cause any piston to wall problems even its over the piston to wall spec in the factory manual? but where can i rent or borrow a dial bore gauge? i dont want to purchase it because i wont use it all the time.. anyways what aftermarket rings are reccomended and where can i get them?
03-21-2005, 04:18 PM
#24
Member
Re: measuring piston ring end gap, too wide? (HKSone)
Go back to the machine shop and have them measure the piston and cylinder size while you are there, then worry about the ring gap. If the bore is too big you are stuck.
03-21-2005, 05:37 PM
#25
Honda-Tech Member
Join Date: Mar 2003
Location: Hudson, NH, 03051
Posts: 3,333
Likes: 0
Received 0 Likes
on
0 Posts
Re: measuring piston ring end gap, too wide? (HKSone)
Piston to cylinder wall clearance is listed as .0004"-.0016".The service limit is .0020".I would go as far as .0030" but that is it.To much clearance will be very noisy and allow the piston to rock in the bores.This WILL break a oem cast piston.If your clearance is excessive you will need to go to the next oversize.
Glenn
Glenn