318 head porting for the average joe

That push rod pinch or bump in the port is NOT as big of restriction as it LOOKS.

3 angle Valve job, Then bowl blending, Then guide trimming, Then inlarging bowl area..............At this point you have got the air flow though the head high enough that the push rod pinch is now the choke point.(smallest area or size...aka RESTRICTION)

If you figure the "area" in each section of the port. you will find that the prp (push rod pinch)is one of the larges area of the port is stock form.

My opinion is from playing with the 340/360 heads. The 318 heads my be different!.?