compression??

Hey guys..
I want to up my comp.. running 135 & want to bump it up to 170/180.
Anyone know how much to skim off the head.

cheers :?

... took .8mm of mine, which took it to 170

was that on a 701 or 760? Mine is a 701.

If your running 135 then you need new rings, 1mm takes them to 175 and 1.5mm takes them to 185

mine is 760, however I did the same when it was 701 barrels .. to get 170

it makes a difference also if you are testing compression with throttle open or closed.
I'm not sure which is the best - i test mine open

throttle closed on a fresh standard standard motor (cold) read 140, full open it read 155

Both plugs out with throttle open

Re-tested with throttle open & closed and both tests were 140.
Thanx for your info...

cheers :wink:

,,,also
...if your battery strength is low...

it needs to turn over proper and fast.
this can make a significant difference

140 is still pretty shit. 155 is standard.
1.2mm off gives you about 180, pump gas (98) is still fine at that..

if you take 1mm or more off you might find you need to re-cut the squish ... you will know if you start blowing head gaskets

But there is no replacement for displacement.

You should be redoing the squish no matter how much you take off

Yes indeed, not remachining the squish is that is a recipe for a chernobyl style disaster! Conrods only bend once! And no I am not speaking from my experance, Kind of funny when it happens to others though.