PGT

just been reading about the cause of head failures on rover K series and apparently much of its down to excessive skimming of the head which is made of LM25 alloy. this stuff is heated and quenched to face harden it and after repeated skims you have lost all the face hardening.

it appears that unless a YB haed is made of this or similar exotic material then repeated face skimming wont affect its face hardness. anyone know the material of a yb head?

abdr500

iTrader: (1)

a rover head fail because of the head gasket that why the do a head gasket conversion set which solves this problem .any ways for a head to get skimmed over and over would simply show a serious underlying fault that is misdiagnose with head gasket if I remember that the rover use liner the can also crack or lift and give the same symptoms as head gasket

PGT

well cossie heads get skimmed a lot. just wonderded if the thoery that the face gets soft after a lot of skimming was correct. this would only be the case if the material was LM25 or similar.

anyone know the material used?

abdr500

iTrader: (1)

PGT
well it only take a few skims on a cosworth head for alot of tunners not to use them on turbo aplication so skimimg them isnt only about strenght its also sqwish band area that gets affected the most

PGT

thanks for your replies abdr - some people hold the view that the yb head face softens when skimmed so just wondered about the material thats all - anyone know?

tabetha

You cannot alter the molecular structure of the head by skimming.
There is "work hardening", which is different, so in comparison to this it would seem soft.
The reason why they are not skimmmed much is as said due to CR going up, they are already a (comapritively) high CR for FI application.
The reason K series head gaskets go is because the original ones had PLASTIC DOWELS which allowed head movement, later headsets contain METAL ones.
The very latest head set of 1800 disco(k series) is a different material type altogether.
My freinds business is doing at least 3/5 a week(k series) and has been for at least 10 years!!
tabetha

Micky The Finn

exactly as that man (or woman) says.

tabetha

MAN, and a fat one at that!!
tabetha

Micky The Finn

girls name!!