Could someone break down the specs on a set of heads? I'm not sure what the 59cc refers to or the 250cc refers to in a set of heads. or the ange degree 13, 16 etc. Or the flow charts listed under a particular set of heads. Just want to know what i'm looking at when shopping! thanks for the info!
59cc refers to the amount of volume the combustion chamber can hold.
This is the combustion chamber.
250cc refers to the intake port runners measured in the same fashion. Filled up and measured with the valves closed. Exhaust ports same way.
As for the valve angle I believe it is measured in reference to the piston at TDC but I'm not certain on that. Different valve angles account for better flow and different characteristics of how the combustion process happens.
Flow numbers don't mean ****. Go by real world testing when looking for heads. A lot of companies skew the numbers and use pipes on the flow fixtures to inflate numbers. I had a set of 243s and they didn't flow over 300cfm on the intake side yet I ran 125 mph in the 1/4 and made more power than most LS1's with larger heads.
No, the bigger the combustion chamber the less your compression ratio is.
I run the 317 casted head witch has a 72cc cumbustion chamber, this droped my compression down about 1/2 point. So now I'm around 9.4:1 from 10:1 compression. Stick a 59cc head on your moter and you'll start to bump the compression up to the 11:1 mark. This is all with a (stockish style) flat top piston.
Big combustion chamers = lower compression ratio, good for forced induction bad for a N/A motor.
For a N/A app you would want to bump up the compression, just watch the smaller cc combustion chambers heads can cause you piston to valve clearance problems depending on how big your cam is.