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250 compression

3K views 8 replies 3 participants last post by  Richardlss 
#1 ·
with a stock 250 the compression should be 8:1... but im getting the head milled, taking .30" (i think its .30") with that small of a number how much difference does it make in compression?
 
#3 ·
what is the normal mill thickness people usually get shaved off their heads?
i finally found a calculator for compression ratio's and it said to get 9.1 compression i need to take off 0.048"...
wouldnt that be 8.8-1? unless its just rounded off? :confused:
 
#5 ·
you had your head milled .100? what is the difference in horsepower do you know? i've been trying to figure out how much horsepower gain i could get out of 8.1 compression to 8.5 compression, if theres a good amount of gain, id probably just step up to 9.1 compression
 
#6 ·
l had 50thou off the head then 50 off the block when it was getting milled.
power wise l dontr know but l got alot of torque drop it in 2nd gear do donuts alllll day
but l'v worked the motor of just a tad bit more also running 97prem
 
#8 ·
It may have just rounded it off,I don't know for sure. I have it in notes somewhere when i was told. and i am pretty sure it was like 2 points for every .010 milled. When I get a half a chance I'll call the guy again just to double check and make sure i am remembering it right. But the call will have to wait till monday.
 
#9 ·
Hey guys, i cant really find a good compression calculator, so i was wondering if any of you knew a good one to get?
just trying to figure out how much HP gain im getting
block is stock with the 3.875x3.53 bore/stroke
74CC head
not sure gasket thickness
but the head is getting milled probably .030" or .040"
and also the block may be getting milled .030" or .040"
if .010" is 2 points of compression then the total .060" is 9.2-1 and .080" is 9.4-1 right?
just getting excited about more compression for some reason
 
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