2.5NA maximum head skim?

90project · May 5, 2020

Hi everyone
For a 2.5 NA (12J) does anyone know what the minimum clearance is between valve face and cylinder head gasket face?
I have a a head which I suspect has been skimmed several times. The valve faces still sit below the gasket face of the head...but only just! Is there likely to be a clearance issue with the top of the pistons?
I cant find a minimum clearance value listed anywhere.
Many Thanks
Andy

jamesmartin · May 5, 2020

no spec was given,you can cut valve seats to sit valve further in

90project · May 5, 2020

jamesmartin said:
no spec was given,you can cut valve seats to sit valve further in

Thanks
The value I’m looking for (as I’ve just been advised) is ‘Valve stand-down’. If I check valve/piston clearance with plasticine what sort of value am I looking for?
Ta!

jamesmartin · May 5, 2020

90project said:
Thanks
The value I’m looking for (as I’ve just been advised) is ‘Valve stand-down’. If I check valve/piston clearance with plasticine what sort of value am I looking for?
Ta!

it is indeed termed as such but there aint no value given, the pistons dont protrude above the block like on late engines, your best bet is to fit the head using the old gasket if possible and use your plasticine then turning the engine over twice

90project · May 5, 2020

jamesmartin said:
it is indeed termed as such but there aint no value given, the pistons dont protrude above the block like on late engines, your best bet is to fit the head using the old gasket if possible and use your plasticine then turning the engine over twice

Cheers...much appreciated

2.5NA maximum head skim?

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