Double checking head gasket thickness
Double checking head gasket thickness I have ported 243's with 65cc's I'm going to install on my LS1 so going off the sticky thread I should be at 10.4cr with a .060 gasket, 10.6cr with a .051 gasket, and 10.7cr with a .040 gasket.
SO I'm wondering if I'll be alright with the .040 gasket or would I have any issues?
No cam yet because I need to figure out my gasket thickness for the Pat G questionnaire.
SO I'm wondering if I'll be alright with the .040 gasket or would I have any issues?
No cam yet because I need to figure out my gasket thickness for the Pat G questionnaire.
Launching!
Joined: May 2012
Posts: 209
Likes: 1
From: NC
Ideally you would look at the platform of intended use. If it is NA then you need to optimize quench and squish - ~ 0.030 to 0.035 being the range that is recommended. This is for optimal efficiency for flame travel over the piston surface area. If you are using NOS under a 300 shot then tune it NA and pull timing. Over 300 then other factors come into play or tend to be much more important.
You need to take into consideration lift of IVC and EVC events if you're eyeballing a high lift narrow LSA design - especially with larger rocker ratios. If you optimize quench and use a radical cam then you will need to consider clearancing the pistons for PTVC.
Every build is different. You can get general ideas from the stickies but in reality it boils down to your intended purpose and measurement(s).
You need to take into consideration lift of IVC and EVC events if you're eyeballing a high lift narrow LSA design - especially with larger rocker ratios. If you optimize quench and use a radical cam then you will need to consider clearancing the pistons for PTVC.
Every build is different. You can get general ideas from the stickies but in reality it boils down to your intended purpose and measurement(s).
Ideally you would look at the platform of intended use. If it is NA then you need to optimize quench and squish - ~ 0.030 to 0.035 being the range that is recommended. This is for optimal efficiency for flame travel over the piston surface area. If you are using NOS under a 300 shot then tune it NA and pull timing. Over 300 then other factors come into play or tend to be much more important.
You need to take into consideration lift of IVC and EVC events if you're eyeballing a high lift narrow LSA design - especially with larger rocker ratios. If you optimize quench and use a radical cam then you will need to consider clearancing the pistons for PTVC.
Every build is different. You can get general ideas from the stickies but in reality it boils down to your intended purpose and measurement(s).
You need to take into consideration lift of IVC and EVC events if you're eyeballing a high lift narrow LSA design - especially with larger rocker ratios. If you optimize quench and use a radical cam then you will need to consider clearancing the pistons for PTVC.
Every build is different. You can get general ideas from the stickies but in reality it boils down to your intended purpose and measurement(s).
Before you can figure quench, the OP needs to know how much the piston comes out or is below the hole. He needs to calculate his deck height in correlation to where the piston is at TDC. After he knows this, then he can select a headgasket. Most guys that give info here seem to leave this important measurement out when talking about quench. From my experience not all LS motors are equal and vary as to how much the pistons come out of the hole.
OP you need to measure.
OP you need to measure.
Launching!
Joined: May 2012
Posts: 209
Likes: 1
From: NC
Before you can figure quench, the OP needs to know how much the piston comes out or is below the hole. He needs to calculate his deck height in correlation to where the piston is at TDC. After he knows this, then he can select a headgasket. Most guys that give info here seem to leave this important measurement out when talking about quench. From my experience not all LS motors are equal and vary as to how much the pistons come out of the hole.
OP you need to measure.
OP you need to measure.
If it's a stock shortblock, .006 to .010" out of the head is a good guesstimate when purchasing parts. Of course you measure at TDC, and if you do, you can always order gaskets and overnight them to you. But .040" should be safe. If you had a blueprinted shortblock, .036" would be acceptable if it were Zero Decked.
TECH Fanatic
Joined: Jun 2011
Posts: 1,343
Likes: 8
From: Katy, TX
Here are some equations I used that may help you. Good luck with the build!
http://www.scribd.com/doc/145057435/...RAFT-01-Jun-13
http://www.scribd.com/doc/145057435/...RAFT-01-Jun-13
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If it's a stock shortblock, .006 to .010" out of the head is a good guesstimate when purchasing parts. Of course you measure at TDC, and if you do, you can always order gaskets and overnight them to you. But .040" should be safe. If you had a blueprinted shortblock, .036" would be acceptable if it were Zero Decked.
Here are some equations I used that may help you. Good luck with the build!
http://www.scribd.com/doc/145057435/...RAFT-01-Jun-13
http://www.scribd.com/doc/145057435/...RAFT-01-Jun-13
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Most guys tend to assume things that shouldn't be assumed. I had not read the thread but assumed deck height and piston height were mentioned if discussion of compression ratios were given. If you're talking about headgasket thickness without the common sense to measure your own block then you have no business building the motor.
The .040's should be fine, heads aren't milled much if at all so piston/valve clearance won't be an issue and neither will compression be an issue as its an N/A build.
He's using a stock short block, not like it's a custom built race short block with aftermarket pistons and such. So it is ok to assume the piston/deck heights.
The .040's should be fine, heads aren't milled much if at all so piston/valve clearance won't be an issue and neither will compression be an issue as its an N/A build.
The .040's should be fine, heads aren't milled much if at all so piston/valve clearance won't be an issue and neither will compression be an issue as its an N/A build.
TECH Senior Member
Joined: Mar 2004
Posts: 14,620
Likes: 17
From: BFE
He's using a stock short block, not like it's a custom built race short block with aftermarket pistons and such. So it is ok to assume the piston/deck heights.
The .040's should be fine, heads aren't milled much if at all so piston/valve clearance won't be an issue and neither will compression be an issue as its an N/A build.
The .040's should be fine, heads aren't milled much if at all so piston/valve clearance won't be an issue and neither will compression be an issue as its an N/A build.
