318 head porting for the average joe
Being that you mentioned the magic numbers on a few things.....
flow over 210cfm int/145cfm exh cfm w/1.78 factory valves and valve job.
145 cfm 'stock 340 exh flow numbers w/1.60'
u shoot from 118/120cfm...to 145-150cfm w/ 1.50 valve
And people wonder why I would rather invest in a 318 head on a 318 instead of a 360 head on a 318. Smaller valves, higher velocity, and flow numbers that equal the bigger port/valved head. Your numbers match a stock big valve 340/360 head, if not better than some.
This 318 head will out perform a 340/360 head, give snappier throttle response and mileage because the air is moving quicker to atomize the fuel for a better more complete burn for more power.
There is a point where the bigger head is better, but for most street and mild street strip 318 builds, stay with the 318 head. Purchase a few tools and learn how to do it.
When the time comes to really step up at the plate looking for some serious power, either be brave and cut away or head down to your local head porter for a "PRO" job that will make you shine.
