Head Gasket Decision
Thread Starter
Joined: Jan 2011
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From: North Houston
Head Gasket Decision I'm building a 346 LS1 with flat (0cc) pistons, stock rotating assembly, LS6 cam and 799 heads milled to 62.5cc. I have new GM MLS head gaskets (02+ LS1 gaskets, p/n 12498544), which will put my DCR and SCR where I want them to be, at 7.5 and 10.9.
However, that's using 0.052" as the compressed gasket thickness, taken from an LS1Tech FAQ. Others have indicated the compressed thickness of the 02+ GM MLS gasket is 0.056" and even 0.060". At 0.060", I would be 7.4 and 10.7.
I have no problem with 7.4 and 10.7 SCR and DCR, but that would put my quench distance at 0.054", which is high from everything I read and is asking for detonation. If the 0.052" dimension is correct, quench is 0.046", which seems to be acceptable.
Here are my questions: 1. Has anyone here verified a GM MLS 02+ head gasket thickness? 2. Is a 0.054" quench distance really too much? 3. Is 0.046" alright for a daily driver destined for 10k+ miles a year? 4. Has anyone used Cometic 0.051" MLS LS1 gaskets without issue?
Here are the values I used:
Rod Length = 6.098"
Deck Height = -0.006"
Cylinder Bore = 3.898" (not honed)
Piston Dome = 0cc
Stroke = 3.622"
Gasket Thickness = 0.052", then 0.060"
Cylinder Head Volume = 62.5cc
Intake Closes ABDC = 80deg
Boost Pressure = 0psi
Altitude = 0ft
Thanks in advance!
However, that's using 0.052" as the compressed gasket thickness, taken from an LS1Tech FAQ. Others have indicated the compressed thickness of the 02+ GM MLS gasket is 0.056" and even 0.060". At 0.060", I would be 7.4 and 10.7.
I have no problem with 7.4 and 10.7 SCR and DCR, but that would put my quench distance at 0.054", which is high from everything I read and is asking for detonation. If the 0.052" dimension is correct, quench is 0.046", which seems to be acceptable.
Here are my questions: 1. Has anyone here verified a GM MLS 02+ head gasket thickness? 2. Is a 0.054" quench distance really too much? 3. Is 0.046" alright for a daily driver destined for 10k+ miles a year? 4. Has anyone used Cometic 0.051" MLS LS1 gaskets without issue?
Here are the values I used:
Rod Length = 6.098"
Deck Height = -0.006"
Cylinder Bore = 3.898" (not honed)
Piston Dome = 0cc
Stroke = 3.622"
Gasket Thickness = 0.052", then 0.060"
Cylinder Head Volume = 62.5cc
Intake Closes ABDC = 80deg
Boost Pressure = 0psi
Altitude = 0ft
Thanks in advance!
The most common spec I've seen for GM LS1 MLS gaskets is .051" thick, but I've also seen .054" posted too. I typically use .051" in my calculations and that seems to be okay. By the way, I have 62cc 243 heads with GM MLS gaskets and everything else almost exactly like what you have and my engine runs great. I think you'll be fine.
Thread Starter
Joined: Jan 2011
Posts: 1,921
Likes: 80
From: North Houston
The most common spec I've seen for GM LS1 MLS gaskets is .051" thick, but I've also seen .054" posted too. I typically use .051" in my calculations and that seems to be okay. By the way, I have 62cc 243 heads with GM MLS gaskets and everything else almost exactly like what you have and my engine runs great. I think you'll be fine.
any track times or power numbers by any chance?I've had the head gaskets for almost a year in anticipation of this build, and I believe I saw 0.051". I found my original calculations from a year ago when I bought the gaskets, and while I didn't write down all the dimensions I used (d'oh!), the calculated SCR was 10.9:1. So I bet I used what you're quoting, 10.9:1. However, seeing people advertise 0.060" compressed is really unnerving! That could be the difference between great quench and bad quench. Thus why I'm considering the Cometic 0.051" MLS gaskets, because knowing is more than half the battle here
Last dyno numbers were 430/408 through a stalled A4. My cam is quite a bit bigger cam than the LS6 cam, although I have a porky GTO. My PB is 11.1 with nitrous and I'm trying to break into the 10's.
Thread Starter
Joined: Jan 2011
Posts: 1,921
Likes: 80
From: North Houston
Well those are some pretty nice results, congrats 
Last chance, anyone have any input on the Cometic MLS 0.051 head gaskets or measured compressed 02+ GM MLS head gaskets for thickness? I'm picking up the short block Friday and would like to know if I need to order alternate gaskets... Thanks!
Last chance, anyone have any input on the Cometic MLS 0.051 head gaskets or measured compressed 02+ GM MLS head gaskets for thickness? I'm picking up the short block Friday and would like to know if I need to order alternate gaskets... Thanks!
Thread Starter
Joined: Jan 2011
Posts: 1,921
Likes: 80
From: North Houston
