fivestardsm
Well-known member
I have been looking for a thicker mill headgasket. Anybody got any suggestion, prefferences?
Which one would be the best to use.
Thanks.
Which one would be the best to use.
Thanks.
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Thick Head gasket, which and where ??
- Thread starterfivestardsm
- Start date
Mitsu MLS, FelPro MLS, HKS MLS, lastly Cometic.
fivestardsm
Well-known member
What is the stock compressed thickness? and do the mitsu ones come thicker? I need details. /ubbthreads/images/graemlins/grin.gif
Last edited:
fivestardsm
Well-known member
What do yu mean by squish? Are you saying that it will make it squish into the cylinder? /ubbthreads/images/graemlins/dunno.gif
1990ggsxnj
Well-known member
Hmmm...The clamping force of the head bolts...or the compression "squish" at TDC?
Quoting H05TYL:
bare in mind a thicker head gasket will mess up the "squish" at the edge of the cylinders
Quoting H05TYL:
bare in mind a thicker head gasket will mess up the "squish" at the edge of the cylinders
boostedinaz
Well-known member
Why do you need a thicker gasket?
Dialcaliper
Well-known member
Stock compressed thickness is between 1.0 to 1.1mm depending on what source you look at.
The Mitsu MLS is 1.4mm compressed. Most of the Cometic/Fel-Pro MLS are 1.0mm. HKS makes a 1.6mm MLS gasket, but it's quite expensive, and hard to find.
The squish zone is the flat rim around the edge of the piston - when the piston comes up (after the spark has fired), the gasses in this area are still cooler, and get "squished" and squirted into the center of the cylinder, supposedly reducing the potential for knock.
With a gasket that is larger than the bore, some of this gas gets compressed out into the gap between the head and block instead of inward, and the knock suppression effect can be slightly reduced, although everything else will still function just fine.
The Mitsu MLS gasket only comes in one size, and is made to accomodate an .040 over bore, so using it with standard or 0.20" over pistons can leave the gap. This is one argument for boring 0.40" over if you don't mind sacrificing the ability to rebore the block (factory pistons come only up to .040 over - aftermarket pistons are made up to 0.60 over, but you need to use a special Cometic or Fel-Pro .060 over head gasket - no big deal, but your block will only have one additional rebuild instead of 2 or 3, in the event that something goes wrong)
The best choice for thick headgasket is the Mitsu MLS. Stock or .020 will work fine, but .040 over is more ideal. You'll still lose a bit of squish effectiveness, since the gap will be 1.4mm instead of 1.0mm, but it's not much to worry about - if you deck your block, it will make the gap tighter (the Mitsu gasket is thicker specifically to make up for the deck height lost when you resurface the head and block for a rebuild)
If you don't plan on resurfacing (recommended if you're using any MLS gasket by the way), the Cometic or Fel-Pro are also fine choices, but with a decked head/block, your piston to valve clearances will be reduced.
Quoting fivestardsm:
What is the stock compressed thickness? and do the mitsu ones come thicker? I need details. /ubbthreads/images/graemlins/grin.gif
The Mitsu MLS is 1.4mm compressed. Most of the Cometic/Fel-Pro MLS are 1.0mm. HKS makes a 1.6mm MLS gasket, but it's quite expensive, and hard to find.
The squish zone is the flat rim around the edge of the piston - when the piston comes up (after the spark has fired), the gasses in this area are still cooler, and get "squished" and squirted into the center of the cylinder, supposedly reducing the potential for knock.
With a gasket that is larger than the bore, some of this gas gets compressed out into the gap between the head and block instead of inward, and the knock suppression effect can be slightly reduced, although everything else will still function just fine.
The Mitsu MLS gasket only comes in one size, and is made to accomodate an .040 over bore, so using it with standard or 0.20" over pistons can leave the gap. This is one argument for boring 0.40" over if you don't mind sacrificing the ability to rebore the block (factory pistons come only up to .040 over - aftermarket pistons are made up to 0.60 over, but you need to use a special Cometic or Fel-Pro .060 over head gasket - no big deal, but your block will only have one additional rebuild instead of 2 or 3, in the event that something goes wrong)
The best choice for thick headgasket is the Mitsu MLS. Stock or .020 will work fine, but .040 over is more ideal. You'll still lose a bit of squish effectiveness, since the gap will be 1.4mm instead of 1.0mm, but it's not much to worry about - if you deck your block, it will make the gap tighter (the Mitsu gasket is thicker specifically to make up for the deck height lost when you resurface the head and block for a rebuild)
If you don't plan on resurfacing (recommended if you're using any MLS gasket by the way), the Cometic or Fel-Pro are also fine choices, but with a decked head/block, your piston to valve clearances will be reduced.
Quoting fivestardsm:
What is the stock compressed thickness? and do the mitsu ones come thicker? I need details. /ubbthreads/images/graemlins/grin.gif
fivestardsm
Well-known member
Awesome explination^^^ /ubbthreads/images/graemlins/worthy.gif
I just got back from the machineshop and we inspected everything and well... I have to repair the block. I am not doing a bore at the moment on this engine, but as for the knock issue from the "squish" factor, It shouldn't be an issue. The motor will be pretty much stock right now, so no high boost limits. I am going to go with the Mitsu gasket with ARP's. now knowing that it is a little thicker. This will give me a little more room to play. As for now, I am headed out to the shop to do some grinding and welding to get the gouge taken care of. I will post pics of the process before and after I have the block surfaced/decked to tolerances.
Thank you Dialcaliper, and all of you guys for the info that you have supplied me with.
P.S. Before anybody starts to rip this thread apart because I will be welding on the block deck/ cylinder bore surface... just don't, I know what I am doing. /ubbthreads/images/graemlins/grin.gif
I just got back from the machineshop and we inspected everything and well... I have to repair the block. I am not doing a bore at the moment on this engine, but as for the knock issue from the "squish" factor, It shouldn't be an issue. The motor will be pretty much stock right now, so no high boost limits. I am going to go with the Mitsu gasket with ARP's. now knowing that it is a little thicker. This will give me a little more room to play. As for now, I am headed out to the shop to do some grinding and welding to get the gouge taken care of. I will post pics of the process before and after I have the block surfaced/decked to tolerances.
Thank you Dialcaliper, and all of you guys for the info that you have supplied me with.
P.S. Before anybody starts to rip this thread apart because I will be welding on the block deck/ cylinder bore surface... just don't, I know what I am doing. /ubbthreads/images/graemlins/grin.gif
Last edited:
slugsgomoo
Well-known member
Quoting Dialcaliper:
Stock compressed thickness is between 1.0 to 1.1mm depending on what source you look at.
The Mitsu MLS is 1.4mm compressed. Most of the Cometic/Fel-Pro MLS are 1.0mm. HKS makes a 1.6mm MLS gasket, but it's quite expensive, and hard to find.
The squish zone is the flat rim around the edge of the piston - when the piston comes up (after the spark has fired), the gasses in this area are still cooler, and get "squished" and squirted into the center of the cylinder, supposedly reducing the potential for knock.
With a gasket that is larger than the bore, some of this gas gets compressed out into the gap between the head and block instead of inward, and the knock suppression effect can be slightly reduced, although everything else will still function just fine.
The Mitsu MLS gasket only comes in one size, and is made to accomodate an .040 over bore, so using it with standard or 0.20" over pistons can leave the gap. This is one argument for boring 0.40" over if you don't mind sacrificing the ability to rebore the block (factory pistons come only up to .040 over - aftermarket pistons are made up to 0.60 over, but you need to use a special Cometic or Fel-Pro .060 over head gasket - no big deal, but your block will only have one additional rebuild instead of 2 or 3, in the event that something goes wrong)
The best choice for thick headgasket is the Mitsu MLS. Stock or .020 will work fine, but .040 over is more ideal. You'll still lose a bit of squish effectiveness, since the gap will be 1.4mm instead of 1.0mm, but it's not much to worry about - if you deck your block, it will make the gap tighter (the Mitsu gasket is thicker specifically to make up for the deck height lost when you resurface the head and block for a rebuild)
If you don't plan on resurfacing (recommended if you're using any MLS gasket by the way), the Cometic or Fel-Pro are also fine choices, but with a decked head/block, your piston to valve clearances will be reduced.
Quoting fivestardsm:
What is the stock compressed thickness? and do the mitsu ones come thicker? I need details. /ubbthreads/images/graemlins/grin.gif
even though .040 is potentially fine, i'll take the trade off and not cut the block as far. I'd recommend staying with .020 if you're boring the block. /ubbthreads/images/graemlins/dunno.gif
Stock compressed thickness is between 1.0 to 1.1mm depending on what source you look at.
The Mitsu MLS is 1.4mm compressed. Most of the Cometic/Fel-Pro MLS are 1.0mm. HKS makes a 1.6mm MLS gasket, but it's quite expensive, and hard to find.
The squish zone is the flat rim around the edge of the piston - when the piston comes up (after the spark has fired), the gasses in this area are still cooler, and get "squished" and squirted into the center of the cylinder, supposedly reducing the potential for knock.
With a gasket that is larger than the bore, some of this gas gets compressed out into the gap between the head and block instead of inward, and the knock suppression effect can be slightly reduced, although everything else will still function just fine.
The Mitsu MLS gasket only comes in one size, and is made to accomodate an .040 over bore, so using it with standard or 0.20" over pistons can leave the gap. This is one argument for boring 0.40" over if you don't mind sacrificing the ability to rebore the block (factory pistons come only up to .040 over - aftermarket pistons are made up to 0.60 over, but you need to use a special Cometic or Fel-Pro .060 over head gasket - no big deal, but your block will only have one additional rebuild instead of 2 or 3, in the event that something goes wrong)
The best choice for thick headgasket is the Mitsu MLS. Stock or .020 will work fine, but .040 over is more ideal. You'll still lose a bit of squish effectiveness, since the gap will be 1.4mm instead of 1.0mm, but it's not much to worry about - if you deck your block, it will make the gap tighter (the Mitsu gasket is thicker specifically to make up for the deck height lost when you resurface the head and block for a rebuild)
If you don't plan on resurfacing (recommended if you're using any MLS gasket by the way), the Cometic or Fel-Pro are also fine choices, but with a decked head/block, your piston to valve clearances will be reduced.
Quoting fivestardsm:
What is the stock compressed thickness? and do the mitsu ones come thicker? I need details. /ubbthreads/images/graemlins/grin.gif
even though .040 is potentially fine, i'll take the trade off and not cut the block as far. I'd recommend staying with .020 if you're boring the block. /ubbthreads/images/graemlins/dunno.gif
bazeng
Well-known member
Dialcaliper, great explanation.
You should be named the VR4 encyclopedia... does all this stuff come off the top of your head?
You should be named the VR4 encyclopedia... does all this stuff come off the top of your head?
Quote:
Dialcaliper, great explanation.
Indeed, thanks.
The difference between understanding a concept, and knowing how to relate that concept to others is something I am, unfortunately, quite familiar with.
It seems you suffer no such indignity.
Dialcaliper, great explanation.
Indeed, thanks.
The difference between understanding a concept, and knowing how to relate that concept to others is something I am, unfortunately, quite familiar with.
It seems you suffer no such indignity.
