Hi there, recently brought a PB head, now if nothing else I need a good skim, its clearly had a HGF. Piston 1 exhaust is full of oil and the area around the recess for piston one on the head looks pretty shagged, now some of the dimples and scrathes etc and pretty damn deep. What is the absolute MAXIMUM I can take off? Obviously I dont want to take more than a few thou off if possible but it's probably gonna need more than that. Cheers Alec
IIRC 6 thou is recommended. For how much a second hand head will cost from ebay, i would say it might be worth just getting a different one.
It depends on a lot of things, but mostly on what you want to use the engine for, and what spec it's going to be. 6-8 thou is probably a normal sort of amount for a light skim. Taking 1mm off the head (1mm = 40 thou of an inch) will take the CR up to 11:1, which is good for a fast road engine, but if you don't mod the fuelling to suit it'll pink itself to death, or the knock sensor will retard the timing miles back and it won't go worth a damn. The other thing you have to be careful of is, because of the tapered shape of the combustion chamber, if you take too much off, the the piston can contact the side of the chamber. If you post up some pics of this head people could give you an opinion on it. Sounds wrecked though. Where did you get it from?
there is a little lip where the engine lifting bracket is on the head, it should be a lip that is 1.5mm in height. the maximum is where that lip can be cut so that the face of the head is the same height as the lip of the bracket. i would urge you not to go to maximum, if you blow a head gasket and you warp it in the future, you will not be able to take any more off your head and it will be scrap.
Ah thats a cool refrence to use, yeah shouldn't need taking back that far Probably 3/4 of a mm at most, Can get it skimmed for free so will do that and see how much gets taken off and decide weather to keep it or not then :0 thanks for the tips lads cheers alec
