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The last step in the porting process is the unshrouding of the combustion chamber. This is a very critical step for improved airflow, especially for the intake side of things. The first photo shows the intake unshrouding half done...this sort of indicates just how much material is removed from here to let the intake valve breathe, especially at low valve lifts. Comparing the unshrouded chamber next to the stock chamber, there's a noticeable radius to the unshrouded chamber.
The final steps to finish the porting would be to polish the ports and combustion chambers. While I didn't show these final steps here, my preference is to polish the intake ports with 36 grit sanding rolls. The course finish helps to keep the incoming air/fuel atomized. I've noticed a big difference in low rpm and cold-start driveability compared to an 80 grit finish.
For the exhaust ports and the combustion chambers, I like to start with 80 grit and finish off with 180 grit. Carbon buildup is less noticeable with the smoother exhaust ports although the airflow gain is neglible.
That about covers it for basic Opel head porting, it's not rocket science, just common sense stuff and the knowledge of a few small details that can make or break the hp potential.
Bob
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