Head Skimming

[nova_saloon]

Have a C20XE head that could possibly need skimming, what is the normal thickness of a unskimmed block as i do not know weather this head has been skimmed or not. and i dont want to get it skimmed if it puts the compression up to high! what are there to look out for? or what should you not get it skimmed passed! :thumb:

[KSRY]

Good garages (those that do skimming) usually make a small mark on the side (usually a very small drill divet) to indicate if its been skimmed, well the head I've got at the moment has that (two marks)

[nova_saloon]

okay cheers, will look for a mark, still intrested to see what the head would be unskimmed in thickness so i can gauge it all

[Benn]

Why do you think it needs skimming?

[bmw156]

i had my cocast head skimmed and i thought it was really close but it seems fine. there were numerous "drill" hols in one side 3 or 4 IIRC which i thought might be a mark for skimmed history. i asked the guy at the skiming place and he said he has never seen that befor. so was unsure.

[nova_saloon]

Why do you think it needs skimming?

metal ruler test.

Anyone know what the rough thickness of it should be :thumb:

[Iain]

Haynes says cylinder head minimum acceptable height after machining is 135.63 mm

[philip]

xe or LET?

if measure the oil way in the head it should be about 1.7mm iirc. but common sense really, i think 7thou off removes 1cc from the chamber. but on an xe i know people who run heads that are machined flush right the way across(no lip on the dizzy side)

[nova_saloon]

xe or LET?

if measure the oil way in the head it should be about 1.7mm iirc. but common sense really, i think 7thou off removes 1cc from the chamber. but on an xe i know people who run heads that are machined flush right the way across(no lip on the dizzy side)

xe and that would cause some wasting of the fuel explosive potential.!
which oil pipe do you measure

[yayoboy]

^if you havent got it mapped correctly

[nova_saloon]

yes but thats all expensive but anything on head skimming you could give me information on

[philip]

i dont get this...what is the spec of your engine?

and measure the oil WAY on the head(looks like a thermometer sort of shape in the centre of the sealing face). i thnk it should be about 1.7mm or so if unskimmed, obv not 100% but will give you an idea. and tbh for an xe you can take quite alot of meat off it compared to an LET where you want as much as poss.

[yayoboy]

like you said phil, you can take loads of xe heads and be ok, for an example im running wossner pistons in mine, and even with the intruder crown not machined down, i got 11.1 compression, and the intruder crown goes into the chamber 8mm.