Re: File Fit Ring End Gap Specs on Street Motor ?
[Re: Classof70Chally]
#212890
02/03/09 12:42 PM
02/03/09 12:42 PM
|
Joined: Feb 2003
Posts: 12,675
Columbia, CT
moper
I Live Here
|
I Live Here
Joined: Feb 2003
Posts: 12,675
Columbia, CT
|
What kind of rings are they? (brand...) I would use the ring manufacturers spec, with some modifications..lol. I run the tops at the "4 per inch of bore" rule and round up. So 4.355" would get an .018" top ring gap. Unless the piston requires differently. Diamonds don't take anything sprecial. I also run and extra thou per inch of bore on the 2nd ring. A lot has changed in the understanding of how rings work, and the 2nd ring with a larger gap can make more power and run cleaner.
Well, art is art, isn't it? Still, on the other hand, water is water! And east is east and west is west and if you take cranberries and stew them like applesauce they taste much more like prunes than rhubarb does. Now, uh... Now you tell me what you know.
|
|
|
Re: File Fit Ring End Gap Specs on Street Motor ?
[Re: Classof70Chally]
#212891
02/03/09 12:47 PM
02/03/09 12:47 PM
|
Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
|
Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
|
Quote:
I'm getting ready to file fit the rings on my 440 street motor for my sig car and wanted some input on the ring end gap. Most of the tech articles I've read seem to want .004" per inch of bore for the top ring and .003" per inch of bore on the second ring. With a finished bore of 4.350 this works out to .018" for the top (rounded up from .0174) and .013 for the second. The pistons are forged Diamond units made from 4032 aluminum which has 15% silicone added to reduce expansion by 15% . The piston to bore clearance is .0045 as per Diamonds recommendation. The motor will be street driven with NO power adders and a max rpm of around 6,000. Any input would be appreciated. Thanks. 
I tend to use the manufacturers specs but now days
I open the second ring gap up a little larger than
the top.... reason is, if the pressure got by the top
I dont want to try and hold it in and cause ring
flutter on both rings
|
|
|
Re: File Fit Ring End Gap Specs on Street Motor ?
[Re: Classof70Chally]
#212896
02/03/09 02:06 PM
02/03/09 02:06 PM
|
Joined: Feb 2007
Posts: 5,080
organ
maximum entropy
master
|
master
Joined: Feb 2007
Posts: 5,080
organ
|
yes. and i'm VERY surprised they did not recommend a bigger second ring gap. almost everyone does now.
for what is the good life if not doing things thoughtfully?
|
|
|
Re: File Fit Ring End Gap Specs on Street Motor ?
[Re: Classof70Chally]
#212897
02/03/09 02:13 PM
02/03/09 02:13 PM
|
Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
|
Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
|
Quote:
Okay, so if Total Seals specs show .020 for the top then maybe go .022? But they show a spec of .015 or .016 for the second then you would go .022 to .026 ??? 
I would set them at
top ring--- .020
second ring --- .022
also I dont set them loose.... try to be accurate with
your feeler gauges(vertical and square). Dont over
heat the engine the first few times you fire it up
|
|
|
Re: File Fit Ring End Gap Specs on Street Motor ?
[Re: Classof70Chally]
#212900
02/03/09 03:27 PM
02/03/09 03:27 PM
|
Anonymous
Unregistered
|
Anonymous
Unregistered
|
Quote:
OK. So it looks like I will split the difference here and go with .022" for the top ring and .024" for the second ring. Is there anyone here that sees a problem with those specs ???
yes, i see a problem with it. first off, it's a street engine, secondly, it's completely N/A. follow the ring manufacturers specs for your application. round up to the nearest .001 for the gap recommended. the pistons you have, which are high silicon, not silicone, also have a built in balance groove between the top and 2nd ring. this will eliminate the need for such a wide 2nd ring gap.
if it were a racing engine i would have a different recommendation.
|
|
|
Re: File Fit Ring End Gap Specs on Street Motor ?
#212901
02/03/09 03:47 PM
02/03/09 03:47 PM
|
Joined: Feb 2007
Posts: 5,080
organ
maximum entropy
master
|
master
Joined: Feb 2007
Posts: 5,080
organ
|
Quote:
Quote:
OK. So it looks like I will split the difference here and go with .022" for the top ring and .024" for the second ring. Is there anyone here that sees a problem with those specs ???
yes, i see a problem with it. first off, it's a street engine, secondly, it's completely N/A. follow the ring manufacturers specs for your application. round up to the nearest .001 for the gap recommended. the pistons you have, which are high silicon, not silicone, also have a built in balance groove between the top and 2nd ring. this will eliminate the need for such a wide 2nd ring gap.
if it were a racing engine i would have a different recommendation.
that groove is called an accumulator groove, btw.
for what is the good life if not doing things thoughtfully?
|
|
|
Re: File Fit Ring End Gap Specs on Street Motor ?
[Re: maximum entropy]
#212903
02/03/09 04:02 PM
02/03/09 04:02 PM
|
Anonymous
Unregistered
|
Anonymous
Unregistered
|
the 2nd ring will never see the same amount of heat as the top ring, especially in a street application. that combined with the accumulator/ channel/ groove, is the reason for leaving the 2nd ring a small amount tighter in the bore. (less expansion}
that groove is called an accumulator groove, btw.
it's also called a pressure balance channel, a pressure balance groove and a few other things. different names from different piston manufacturers.
Last edited by DRAM_Perf_Only; 02/03/09 04:07 PM.
|
|
|
Re: File Fit Ring End Gap Specs on Street Motor ?
#212904
02/03/09 04:44 PM
02/03/09 04:44 PM
|
Joined: Feb 2007
Posts: 5,080
organ
maximum entropy
master
|
master
Joined: Feb 2007
Posts: 5,080
organ
|
there are definitely numerous ways to skin that cat. the tight gaps concern me. .013 on the second is really tight. be very careful to get the gaps perfectly square ( as you always should ), and don't overheat that thing. i have a very similar build in my street strip car, and i'm at .022 top and .024 second, and have as near zero leak down as a conventional ring engine can have. i seriously doubt one could find a measurable difference in leak down between .013 and .024 on the second ring. the extra silicon, btw, makes for a much more scuff resistant piston. good choice.
for what is the good life if not doing things thoughtfully?
|
|
|
|
|
larger second ring gap has been shown to actually improve top ring seal. it allows combustion gases that have leaked past the top ring to escape past the second, preventing top ring flutter. also, a little too big is way better than a little too small. if the ends ever butt, you've got trouble.
down the track for a time slip just to see what it will do. I appreciate everyones input on this. This is my first 'file fit' ring job and it's nice to have the accumulated engine building knowledge that is available here on this site. 
