Camshaft difference 320/6 - 323i (731 head)

[e21matt]

Hi, I'm new here.

I bought a 323i with a 731 head and not sure about what camshaft it has but should be of a 323i.
The car had a vacuum (suction) on one of the exhaust (they are separate headers, 3 and 3). I had some time to remove the head to see what's wrong.
I found that piston 6 had a dent caused by the exhaust valve hitting it, and the chamber had more carbon than the others.
I am curious about the dent on one piston only, could it be wrong timing?
The pistons are high compression (domed) 9.8:1

From what I know about the car is that initially the head was installed with the 20 camshaft and the previous owner noticed that the car wasn't performing well and changed to the 23 camshaft.

I have checked all valves for leaks by putting gasoline in the exhaust ports and no 6 and 3 have leaked but 6 is the worst.

The intake matches the head and the car has an e30 fuel injection and ecu.

Could you guide me identify what caused the valve to hit the piston and if there is any difference between the 320/6 and 323i camshafts?

Thank you

[WadiM3]

First of all your going to have to search for then 320 cam duration and lift specs and the 323 and compare them but my wild assed guess is that the car wasn't timed correctly, I'd expect the valve to bend or break more then a piston being dented. But hey I'm no mechanic or tech

[dworthy]

Welcome to the Forum!

The reason why you have a dent in the piston, the timing belt has been broken in the past. That leads me to believe that the head you have isn't original, and you will need to get the cam measured for the lift/duration to see if that is the proper cam.