stock piston ring gap - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

s13drob · 02-13-2010, 03:10 PM

im putting together my spare sr20de+T and i wanted to get some info on my piston ring end gap. its stock replacement rings

my old ring gap
1st ring .015
2nd ring .021

new rings
1st ring .011
2nd ring .019

i checked the FSM and i noticed my new rings arent within standard spec.
is it ok to run the new rings at their current spec since the original rings were also way below standard spec? heres a piece from the FSM.
thanks for any help/advice

s13drob · 02-14-2010, 12:59 PM

anybody???????????

*ManoNegra* · 02-14-2010, 01:09 PM

The old ones weren't
the new ones appear to be just within spec
I don't see a reason why not to run them
if you want better clearance they you'll probably need to buy some
and gap them yourself or have someone do it
what pistons did they come with?

s13drob · 02-14-2010, 01:20 PM

its a new oem piston ring set for stock pistons and bore. Am i reading the FSM right? the top ring end gap (for example) should be .20-.30 and new rings are .11. a little too tight right? the thing that confuses me is my old rings were below spec aswell.

tommyboi · 02-14-2010, 02:08 PM

i always heard to go .8 over what the FSM says if your boosting

TrustS13 · 02-14-2010, 02:35 PM

When I built my 4g63 I ran them a little tighter than stock gap from what I can remember. If you run them too loose, you run the risk of piston slap when its cold.

s13drob · 02-14-2010, 02:44 PM

.8 seems a little too much. im thinking im going to have to get a ring grinder and gap them bigger to the loose end of spec. turbo engines require bigger end gap and the more boost the higher you need the end gap iirc. i think its to compensate for the added heat so the rings expand to give a good seal but not touch ends and fail.

i guess i have to grind the rings for a bigger end gap. its just wierd how small of a end gap the new oem rings came. Am i missing something here?

ANY MORE ADVICE ANYONE?

s13drob · 02-15-2010, 01:09 PM

bump...............

midnight_rex · 02-15-2010, 06:53 PM

your rings are within spec. your not reading the FSM right. factory rings should not require any grinding unless your going with different bore.

your new rings:
1st ring .011
2nd ring .019

FSM specs:
1st ring .0079 - .0118 (limit .023)
2nd ring .0136 - .0197 (limit .027)

when you read in measurements like this you want to round it off. there are some machinists that do this but id rather be most accurate then not. also i never read in millimeters. reading in inches give you a better accuracy

s13drob · 02-16-2010, 03:57 AM

WTF? rex your right. i was reading the feeler gauge wrong. haha. this OEM brand gauge is tricky. how the hell did i miss that. haha damn i fail. thanks man.

atleast people can get the ring gap measurements from this thread haha

midnight_rex · 02-16-2010, 05:57 PM

no problem. it never hurts to ask and make sure dude.

02-13-2010, 03:10 PM	#1
s13drob Zilvia Addict Join Date: Jan 2008 Location: socal Posts: 774 Trader Rating: (29) Feedback Score: 29 reviews	stock piston ring gap im putting together my spare sr20de+T and i wanted to get some info on my piston ring end gap. its stock replacement rings my old ring gap 1st ring .015 2nd ring .021 new rings 1st ring .011 2nd ring .019 i checked the FSM and i noticed my new rings arent within standard spec. is it ok to run the new rings at their current spec since the original rings were also way below standard spec? heres a piece from the FSM. thanks for any help/advice

02-14-2010, 12:59 PM	#2
s13drob Zilvia Addict Join Date: Jan 2008 Location: socal Posts: 774 Trader Rating: (29) Feedback Score: 29 reviews	anybody???????????

02-14-2010, 01:09 PM	#3
ManoNegra Guild of Skullduggerous Intent Join Date: Jan 2004 Location: Socal Posts: 7,841 Trader Rating: (48) Feedback Score: 48 reviews	The old ones weren't the new ones appear to be just within spec I don't see a reason why not to run them if you want better clearance they you'll probably need to buy some and gap them yourself or have someone do it what pistons did they come with?

02-14-2010, 01:20 PM	#4
s13drob Zilvia Addict Join Date: Jan 2008 Location: socal Posts: 774 Trader Rating: (29) Feedback Score: 29 reviews	its a new oem piston ring set for stock pistons and bore. Am i reading the FSM right? the top ring end gap (for example) should be .20-.30 and new rings are .11. a little too tight right? the thing that confuses me is my old rings were below spec aswell.

02-14-2010, 02:08 PM	#5
tommyboi Join Date: May 2008 Location: Minnesota Posts: 45 Trader Rating: (5) Feedback Score: 5 reviews	i always heard to go .8 over what the FSM says if your boosting

02-14-2010, 02:35 PM	#6
TrustS13 Zilvia Addict Join Date: Nov 2008 Location: Greensboro, NC Age: 37 Posts: 631 Trader Rating: (16) Feedback Score: 16 reviews	When I built my 4g63 I ran them a little tighter than stock gap from what I can remember. If you run them too loose, you run the risk of piston slap when its cold.

02-14-2010, 02:44 PM	#7
s13drob Zilvia Addict Join Date: Jan 2008 Location: socal Posts: 774 Trader Rating: (29) Feedback Score: 29 reviews	.8 seems a little too much. im thinking im going to have to get a ring grinder and gap them bigger to the loose end of spec. turbo engines require bigger end gap and the more boost the higher you need the end gap iirc. i think its to compensate for the added heat so the rings expand to give a good seal but not touch ends and fail. i guess i have to grind the rings for a bigger end gap. its just wierd how small of a end gap the new oem rings came. Am i missing something here? ANY MORE ADVICE ANYONE?

02-15-2010, 01:09 PM	#8
s13drob Zilvia Addict Join Date: Jan 2008 Location: socal Posts: 774 Trader Rating: (29) Feedback Score: 29 reviews	bump...............

02-15-2010, 06:53 PM	#9
midnight_rex Zilvia Member Join Date: Jul 2008 Location: houston, tx Age: 38 Posts: 239 Trader Rating: (1) Feedback Score: 1 reviews	your rings are within spec. your not reading the FSM right. factory rings should not require any grinding unless your going with different bore. your new rings: 1st ring .011 2nd ring .019 FSM specs: 1st ring .0079 - .0118 (limit .023) 2nd ring .0136 - .0197 (limit .027) when you read in measurements like this you want to round it off. there are some machinists that do this but id rather be most accurate then not. also i never read in millimeters. reading in inches give you a better accuracy

02-16-2010, 03:57 AM	#10
s13drob Zilvia Addict Join Date: Jan 2008 Location: socal Posts: 774 Trader Rating: (29) Feedback Score: 29 reviews	WTF? rex your right. i was reading the feeler gauge wrong. haha. this OEM brand gauge is tricky. how the hell did i miss that. haha damn i fail. thanks man. atleast people can get the ring gap measurements from this thread haha

02-16-2010, 05:57 PM	#11
midnight_rex Zilvia Member Join Date: Jul 2008 Location: houston, tx Age: 38 Posts: 239 Trader Rating: (1) Feedback Score: 1 reviews	no problem. it never hurts to ask and make sure dude.