Did I make my ring gaps too loose?
Thread Starter
Heel & Toe
Joined: Aug 2021
Posts: 18
Likes: 0
Did I make my ring gaps too loose?
Rebuilding the LS6 after cylinder #7 ring land failure & have gone with forged pistons (DSS) & rods (Scat).
First time getting this deep into an engine, so first time gaping rings. DSS spec sheet for the rings recommended bore * 0.005 top & 0.0055 2nd gaps for an NA engine. Which for 3.903 over bore comes out to 19.5 & 21.5, call it 20 & 22 thou.
After the #7 failure and reading various bits of internet wisdom (I know!), I went with bigger gaps: 22 & 26
Now I'm thinking that's too big - it's 15% (top) & 25% (2nd) over the manufacturer recommendation and way above stock.
Are those gaps going to be cause excessive blow by? I'm OK getting another set of rings (that's the cost of learning!).
(the engine has cam, heads, intake, headers; car is 75% track use & will see back to back HPDE sessions).
First time getting this deep into an engine, so first time gaping rings. DSS spec sheet for the rings recommended bore * 0.005 top & 0.0055 2nd gaps for an NA engine. Which for 3.903 over bore comes out to 19.5 & 21.5, call it 20 & 22 thou.
After the #7 failure and reading various bits of internet wisdom (I know!), I went with bigger gaps: 22 & 26
Now I'm thinking that's too big - it's 15% (top) & 25% (2nd) over the manufacturer recommendation and way above stock.
Are those gaps going to be cause excessive blow by? I'm OK getting another set of rings (that's the cost of learning!).
(the engine has cam, heads, intake, headers; car is 75% track use & will see back to back HPDE sessions).
Drifting
Joined: Sep 2009
Posts: 1,862
Likes: 594
From: Prescott, Arizona
I think it is better to have larger gaps for many reasons. I have not seen blow by complaints of large gapped supercharged or turbocharged engines.
If you ever add forced induction you will want larger gaps.
Hot Rod Magazine once disassembled a junkyard 4.3 Liter LS and put it back together with all the original parts, making ONE change -- they gapped the rings at 0.026". This stock junkyard engine was then put on an engine dyno and turbocharged for almost 100 runs, the last of which were just below 1,000 horsepower. The otherwise stock junkyard 4.3 stayed together.
I would definitely add coolant air bleed piping to the rear head ports to join with the front coolant air bleed piping. I have seen some reports on the Forum that claimed lack of such rear head coolant air bleed ports contributed to cylinder #7 failure.
I added rear coolant air bleed piping to my 2001 in August 2017 and am preparing for the car's 27th day on a road course race track.
If you ever add forced induction you will want larger gaps.
Hot Rod Magazine once disassembled a junkyard 4.3 Liter LS and put it back together with all the original parts, making ONE change -- they gapped the rings at 0.026". This stock junkyard engine was then put on an engine dyno and turbocharged for almost 100 runs, the last of which were just below 1,000 horsepower. The otherwise stock junkyard 4.3 stayed together.
I would definitely add coolant air bleed piping to the rear head ports to join with the front coolant air bleed piping. I have seen some reports on the Forum that claimed lack of such rear head coolant air bleed ports contributed to cylinder #7 failure.
I added rear coolant air bleed piping to my 2001 in August 2017 and am preparing for the car's 27th day on a road course race track.
Thread Starter
Heel & Toe
Joined: Aug 2021
Posts: 18
Likes: 0
I would definitely add coolant air bleed piping to the rear head ports to join with the front coolant air bleed piping. I have seen some reports on the Forum that claimed lack of such rear head coolant air bleed ports contributed to cylinder #7 failure.
I added rear coolant air bleed piping to my 2001 in August 2017 and am preparing for the car's 27th day on a road course race track.
I added rear coolant air bleed piping to my 2001 in August 2017 and am preparing for the car's 27th day on a road course race track.
. Which kit did you go with?
Drifting
Joined: Sep 2009
Posts: 1,862
Likes: 594
From: Prescott, Arizona
I made my rear coolant air bleed connections from a 2001 and later front pipe, had to cut it and splice in a short 1/4" heater hose to make it fit. ran 1/4" heater hose around the passenger side valve cover and Teed it in just past the throttle body.
https://www.ebay.com/itm/35391769481...75.c101224.m-1
https://www.ebay.com/itm/35391769481...75.c101224.m-1
Race Director
Joined: Oct 2004
Posts: 12,864
Likes: 4,667
Rebuilding the LS6 after cylinder #7 ring land failure & have gone with forged pistons (DSS) & rods (Scat).
First time getting this deep into an engine, so first time gaping rings. DSS spec sheet for the rings recommended bore * 0.005 top & 0.0055 2nd gaps for an NA engine. Which for 3.903 over bore comes out to 19.5 & 21.5, call it 20 & 22 thou.
After the #7 failure and reading various bits of internet wisdom (I know!), I went with bigger gaps: 22 & 26
Now I'm thinking that's too big - it's 15% (top) & 25% (2nd) over the manufacturer recommendation and way above stock.
Are those gaps going to be cause excessive blow by? I'm OK getting another set of rings (that's the cost of learning!).
(the engine has cam, heads, intake, headers; car is 75% track use & will see back to back HPDE sessions).
First time getting this deep into an engine, so first time gaping rings. DSS spec sheet for the rings recommended bore * 0.005 top & 0.0055 2nd gaps for an NA engine. Which for 3.903 over bore comes out to 19.5 & 21.5, call it 20 & 22 thou.
After the #7 failure and reading various bits of internet wisdom (I know!), I went with bigger gaps: 22 & 26
Now I'm thinking that's too big - it's 15% (top) & 25% (2nd) over the manufacturer recommendation and way above stock.
Are those gaps going to be cause excessive blow by? I'm OK getting another set of rings (that's the cost of learning!).
(the engine has cam, heads, intake, headers; car is 75% track use & will see back to back HPDE sessions).
Drifting
Joined: Apr 2008
Posts: 1,687
Likes: 86
From: De Pere, WI
You will be fine. your gap is about what I am running for my twin turbo 404 LQ4 that should be in the 1100 - 1200 whp range. Per Wiseco, they said I could either run the "Street/Moderate Turbo" or "Turbo/Supercharged Race Only". I split the difference at bore * 0.0055...Your's comes out to about bore * 0.005. You are fine.
