Ross pistons, Mahle rings end gap
#939539
02/28/11 01:12 AM
02/28/11 01:12 AM
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Joined: Feb 2010
Posts: 18,493 Granite Bay CA
Kern Dog
OP
Striving for excellence
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OP
Striving for excellence
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
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I have a 74 440, .030 over with a 4.15 Eagle crank, Manley rods and Ross pistons. I'm filing the Mahle rings to fit and making each ring fit each cylinder. The instructions state .004 end gap for a 4 inch bore for moderate performance and .0055 for street/drag racing. I filed the top rings to .020 and started filing the second rings. The tech sheet recommends a larger gap on the second rings, so I went with .024, which is in keeping with the .0055 street/drag racing spec. I went too far with 2 of the rings. Both measure .030, .006 larger than the others. The tech sheet shows the .030 number for drag nitrous apps. I may drag race the car, but I have no plans to run spray in this motor. Whats the chance that the larger second ring gaps would be a problem? I pulled the 3000 mile engine to address an oil burning problem. I found the oil rings had no tension and the compression rings were worn enough to have end gaps in excess of .050. I performed cranking compression tests several times over the past few years trying to diagnose the oil burning, and the numbers were always in the 180 range and within 6% of each other. With worn rings, I would think those numbers are not bad. With that in mind, would wider gaps on the second ring matter much, if at all? I dont want to be a cheapskate here. If its suggested that I order 2 new rings to make all the end gaps consistant, I'll do it.
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Re: Ross pistons, Mahle rings end gap
[Re: Cab_Burge]
#939542
02/28/11 02:08 AM
02/28/11 02:08 AM
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Joined: Mar 2007
Posts: 3,300 Northern Indiana
Dunnuck Racing
master
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master
Joined: Mar 2007
Posts: 3,300
Northern Indiana
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Quote:
don't worry about the .030 gap on the second rings, they are a scraper ring to help control oil use so go for it. I agree! You are better to err on the large side than to be to tight with the gaps,and end up having a ring's end gap butt together and cause damage. Also,pre-gapped sets are usually that loose anyway. Don't sweat it! Keith
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Re: Ross pistons, Mahle rings end gap
[Re: Kern Dog]
#939546
02/28/11 05:20 AM
02/28/11 05:20 AM
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Joined: Jul 2010
Posts: 2,091 Delray beach, Florida
Performance Only
top fuel
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top fuel
Joined: Jul 2010
Posts: 2,091
Delray beach, Florida
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when your going to great lengths to maske sue everything is just so with a build but something like this ring end gap mistake happens, you just have to ask yourself if you want to correct the mistake, or just forget about making the build as good as you can. it's always easy for people with no vested interest to tell you what you might want to hear. in the end you have to trust your own instincts. in the end, either the work is correct, or it's not. which one are you willing to accept. if it were mine, or a customers engine, we'd correct the mistake. and another way to look at it, if we were building it for you and we told you we made a mistake on the rings, would you be okay with it? or would you "expect" us to correct it. if it's the latter of the two, think about it.
machine shop owner and engine builder
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Re: Ross pistons, Mahle rings end gap
[Re: Performance Only]
#939551
02/28/11 03:38 PM
02/28/11 03:38 PM
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Joined: Dec 2008
Posts: 1,200 UK
602heavy
pro stock
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pro stock
Joined: Dec 2008
Posts: 1,200
UK
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Quote:
when your going to great lengths to maske sue everything is just so with a build but something like this ring end gap mistake happens, you just have to ask yourself if you want to correct the mistake, or just forget about making the build as good as you can. it's always easy for people with no vested interest to tell you what you might want to hear. in the end you have to trust your own instincts. in the end, either the work is correct, or it's not. which one are you willing to accept. if it were mine, or a customers engine, we'd correct the mistake. and another way to look at it, if we were building it for you and we told you we made a mistake on the rings, would you be okay with it? or would you "expect" us to correct it. if it's the latter of the two, think about it.
....cool post.
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Re: Ross pistons, Mahle rings end gap
[Re: Kern Dog]
#939552
02/28/11 04:23 PM
02/28/11 04:23 PM
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Joined: Aug 2003
Posts: 43,307 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,307
Bend,OR USA
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The oil rings NOT mounted on te expanders will have almost or no tension by themselfs One way to check oil ring tension is to mount them (theoil expander and both rings on the pistons with no other rings and not connected to the rod, buy a fish scale and attach it to the wrist pin and slide the piston into the bore upside down all the way to the bottom of the bore so you can pull the piston out of the bore with the fish scale, watch the scale and see how much tension(in lbs) it takes to move the rings and pistons up the bore (Do several pistons in other bores also ) Let us know what you find out , if you do it BTW, it doesn't hurt to check the oil ring end gap also file as or if needed per the ring makers instruction BTW, rotate the block so the bores are parelel(SP?) to the floor so your not fighting gravity
Last edited by Cab_Burge; 02/28/11 04:24 PM.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Ross pistons, Mahle rings end gap
[Re: Cab_Burge]
#939553
02/28/11 06:05 PM
02/28/11 06:05 PM
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Joined: Jul 2010
Posts: 2,091 Delray beach, Florida
Performance Only
top fuel
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top fuel
Joined: Jul 2010
Posts: 2,091
Delray beach, Florida
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Quote:
BTW, rotate the block so the bores are parelel(SP?) to the floor so your not fighting gravity
not to be too picky, but i completely disagree with the above statement. the reasoning behind that is two fold. 1) the piston and pin in a common engine will weight about 2 pounds. if you hang the piston and pin on your scale BEFORE you do the test, you'll know how much those parts weigh. (that's gravity) you can deduct the weight from your test readings. 2) if performed as suggested above, you are more likely to have the piston trying to [Edited by Moparts - Family Friendly Site - Keep it clean] in the bore, giving a somewhat false reading due to excessive skirt drag. i'm of the opinion that when testing ring tension, you should be pulling the piston vertically through a very clean bore with a very lightweight oil, such as marvel mystery oil or transmission fluid. you need some lubrication to get accurate results. don't use 40 or 50 wt. oil for the test. the above is my opinion only and is not intended to provoke or otherwise excite anyone.
machine shop owner and engine builder
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Re: Ross pistons, Mahle rings end gap
[Re: Performance Only]
#939554
02/28/11 07:42 PM
02/28/11 07:42 PM
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Joined: Dec 2008
Posts: 1,200 UK
602heavy
pro stock
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pro stock
Joined: Dec 2008
Posts: 1,200
UK
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Most everyone disagrees but i'll say it anyway .............why go larger on 2nd ring gap?.....if machine work is done correctly for the ring pack being used then blowby should be minimal ,excessive 2nd ring end gaps on street motors will have oil contaminated along with regular oil changes , the larger the 2nd ring end gap the wider the trail of oil entering top ring land through endgap , cast iron rings will expand @ a lesser rate than ductile/steel & will also be subjected to less heat , the iron ring will also wear @ a faster rate than steel , gapping bothe rings the same would end up with a larger 2nd end gap in a running engine....... take the gapless top ring for example , Total Seal say these type rings installed correctly have near on zero blowby , yet they recommend 2nd ring gap to be larger than top end gap , an example was a 4500 bore running nitrous (250 shot) , total seal recommended top ring end gap .007 X bore = .032" , 2nd gap .008 x bore= .036" , this was a street motor whereby engine oil was changed every 1000 miles due to contamination , i'm still baffled as to why Total Seal recommend such large 2nd end gaps considering blowby being near zero with these rings. , i asked the question directly to Total Seal on another forum & got no reply.
Last edited by 602heavy; 02/28/11 07:49 PM.
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