850 Compression Ratio

[gs.davies]

I’ve got a standard 850 head that needs a light skim to remove a bit of surface corrosion. Is there are benefit in getting a more drastic skim done to increase the CR over standard?

If so, how many thou?

[mk1]

If it is otherwise standard, there is no point in doing any more than a skim to get it flat.

[Dearg1275]

I disagree. Raising the compression ratio increases the combustion efficiency and produces more power. The down side is that you will have to use a higher octane fuel or retard the ignition (which defeats the object). If you can run a higher octane fuel then going to 9:1 can only be good news even on a standard 850. Every little bit helps on small bore engines.

D

[bwaminispeed]

You can go 50-60 thou on an 850 head, without problems, on regular fuel.......