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Crankcase evac & low tension oil rings
#1431865
05/07/13 05:58 PM
05/07/13 05:58 PM
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Joined: Aug 2011
Posts: 51
San Diego, USA
SoCalRacer
OP
member
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OP
member
Joined: Aug 2011
Posts: 51
San Diego, USA
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I'm freshening up a 340 +.030 and looking at the different oil ring tensions available. Standard tension is around 20 lbs, but 16 and 11 lb. rings are available from Total Seal. This is a drag race only 12.5:1 motor with open headers that never sees street use. It does not have a vacuum pump but does run a Vac-U-Pan. Does that provide enough negative crankcase pressure to use a lower tension ring set?
If it ain't broke ... you're not pushing it hard enough.
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Re: Crankcase evac & low tension oil rings
[Re: SoCalRacer]
#1431866
05/07/13 06:41 PM
05/07/13 06:41 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
I'm freshening up a 340 +.030 and looking at the different oil ring tensions available. Standard tension is around 20 lbs, but 16 and 11 lb. rings are available from Total Seal. This is a drag race only 12.5:1 motor with open headers that never sees street use. It does not have a vacuum pump but does run a Vac-U-Pan. Does that provide enough negative crankcase pressure to use a lower tension ring set?
If the E-vac is installed correctly yes it helps seal
the rings... it will pull about 5"HG max... is that
the best... NO... you would like to see about 14"hg max
but any negative pressure is a good thing
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Re: Crankcase evac & low tension oil rings
[Re: WO23Coronet]
#1431868
05/07/13 10:42 PM
05/07/13 10:42 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
Why exactly do you need vacuum in the pan with low tension rings? Is it just to prevent blow by? Does it actually make them seal better (push/pull them against the cylinder wall) or just prevent blow by?
Yes it actually seals them better on the lower tension rings
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Re: Crankcase evac & low tension oil rings
[Re: MR_P_BODY]
#1431869
05/08/13 07:45 PM
05/08/13 07:45 PM
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Joined: Aug 2011
Posts: 51
San Diego, USA
SoCalRacer
OP
member
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OP
member
Joined: Aug 2011
Posts: 51
San Diego, USA
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Thanks for the reply. Since the motor is apart I can't quantify how much vacuum it pulled, but it always stayed clean and dry with no smoke. Probably left a few horsepower on the table needlessly so I'm going with the low tension oil rings this time around.
If it ain't broke ... you're not pushing it hard enough.
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