6 replies to this topic

[mike_c]

hi can anybody tell me what the maximum is i can skim off an 850 head to use a standard head gasket

thanks
mike

[Cooperman]

Head gasket in unaffected by how much you skim off a head. Skimming increases the compression ratio and that is the limit really as you can't go much above about 11:1 and even then you need 98 oct petrol plus an octane booster and a re-curved distributor, plus better pistons than come with an 850.
Why do you want to skim to the maximum? Have you done the compression ratio calculations.
To measure how much 'meat' there is between the oil feed hole and the head face measure the depth of the oil hole which feeds the rocker shaft and compare it to the head depth. You should allow a minimum of 0.050" after skimming as a general rule.

[mike_c]

My head has a big dent ware it was droped on something i have taken 0.012" off but its not cleaned up i think it needs the same again if it will be ok.

[Big_Adam]

Got a few spare in the garage is that one starts giving you trouble, small bore spare from 998s.

[Cooperman]

Up to 0.025" won't be a problem. It will increase the C.R. a bit, but that might be an improvement actually if it was standard to begin with.

[mike_c]

Thanks for the help

[Spitz]

I ahve shaved two heads.,.. .080"