720 Rotary valve cover indentations vs smooth?

[andy.262]

My rotary valve cover is shot, deep grooves in it. Looking to get a good used one from eBay, and I'm noticing that many of them have these indentations on the surface that my current one does not have. What is the purpose of these indentations, and are they interchangeable with/without them? Is one better than the other in some way?

I'm seeing that the one with the indentation is stamped 810-527, while the smooth is stamped 810-522 (like my current, damaged one) but they both come from a 720 engine which makes me want to believe they are interchangeable.

 

[etemplet]

Did you lay a straight edge across the surface of your cover just to see what it looks like? Did you do the checks to determine how much clearance you have currently?

I'm not sure if those slots help a lot as they were discontinued. I wouldn't concern myself if there were present or not.

 

[andy.262]

This is from my GTI that the previous owner allowed those cageless needle bearings to fall into the crankcase. Both the rotary surface on the case and the rotary cover have actual chunks taken out of them near the ports and extremely deep groves. I'm getting a good used crankcase and a good used rotary valve cover, so can't really measure anything since I don't have either half yet. This question is just to make sure I don't accidentally purchase a rotary cover that I can't use for whatever reason.