[Mk2] [Turbo] Head skim
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[Mk2] [Turbo] Head skim
I was just wondering how many times a head can take a skimming before you have to think about getting a thicker gasket than the original 1.2mm one. Say you buy a secondhand block and head and want to get them refaced, does it matter if this has already been done at some point.
Re: [Mk2] [Turbo] Head skim
Depends on how much material was taken off the last time.
Putting a thicker gasket is a bodge, personally I'd get a new head as they're dirt cheap
Putting a thicker gasket is a bodge, personally I'd get a new head as they're dirt cheap
Re: [Mk2] [Turbo] Head skim
Can you tell if it's been skimmed?
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Re: [Mk2] [Turbo] Head skim
Using a thicker headgasket is not a bodge. It's standard practice in the tuning game.
Re: [Mk2] [Turbo] Head skim
Using a thicker headgasket alters the squish and is generally not advised to alter CR
Re: [Mk2] [Turbo] Head skim
They're not talking about using one to lower CR though, using a thicker gasket to compensate for a head that's been refaced is perfectly acceptable
EX MR2 owner, currently on a '00 Honda CBR600 Follow me on Instagram @c35rob
Re: [Mk2] [Turbo] Head skim
I guess Rob im referring to a good old skim rather than a reface - you saw the turbo head I had on that turbo that had been skimmed (i.e cheesegrated) twice..... My point there was (and perhaps my ignorance showing here) if it's bad to lower CR with a HG, why is it OK to bring CR up to normal (i.e lower CR) with an overskimmed head?
Natually here i'm assuming that we dont know how much material has been removed and it could / probably is OK to skim twice. But would you? that's where my 'bodge' thought train comes from.
Natually here i'm assuming that we dont know how much material has been removed and it could / probably is OK to skim twice. But would you? that's where my 'bodge' thought train comes from.
Re: [Mk2] [Turbo] Head skim
you can measure a head to see how much has been taken off, there will (should) be a "stock" thickness somewhere in the BGB
the reason it's ok to restore the piston-to-head clearance/CR with a thicker gasket on a skimmed head, and not a good idea to smash a fatty in there to lower compression on an unskimmed head is that the PTH (squish/quench etc) clearance on a skimmed head that has been 'corrected' should be restored to stock, whereas attempting to lower compression with a thick gasket/decomp plate instead of pistons increases the PTH clearance and thus the tendency for knock
the reason it's ok to restore the piston-to-head clearance/CR with a thicker gasket on a skimmed head, and not a good idea to smash a fatty in there to lower compression on an unskimmed head is that the PTH (squish/quench etc) clearance on a skimmed head that has been 'corrected' should be restored to stock, whereas attempting to lower compression with a thick gasket/decomp plate instead of pistons increases the PTH clearance and thus the tendency for knock
EX MR2 owner, currently on a '00 Honda CBR600 Follow me on Instagram @c35rob
Re: [Mk2] [Turbo] Head skim
Ahh, I am once again educated. Perhaps i should pose my answers more as questions eh?
Thanks Rob.
Thanks Rob.
Re: [Mk2] [Turbo] Head skim
[quote="C35Rob"]you can measure a head to see how much has been taken off, there will (should) be a "stock" thickness somewhere in the BGB
Thats interesting Rob, Anyone out there with the Big Green Book able to have a look.
Thats interesting Rob, Anyone out there with the Big Green Book able to have a look.