[Walt Fricke]

I once had a leak like you describe - it appeared to be between the chain housing and the cam tower. As I drove my car with a newly rebuilt engine to my trailer to load, there was a trail of oil - not a pesky drip you can live with for quite a long time.

Turns out I had forgotten to tighten the three 10mm head bolts. As soon as I had the cam gear off this was obvious. Tightened, reassembled, and good to go. I checked the cam timing, but since I hadn't moved the crank or cam, it went back together timed just fine and I didn't have to do anything more. If you moved either, then you must retime. But if you didn't, check as it is before fussing with the timing.

The #4 intake and exhaust rocker shafts can make it look like a leak is in this area. The diagnostic is a rocker shaft which has moved enough that you wouldn't have left it in that position on a rebuild.

It looks to me like you used a non-hardening sealant? I've had good luck with those for some applications. Though in this application you seldom have to pull that aluminum holder - not like, say, valve cover gaskets, where you should periodically take the covers off to check this or that.

Anyway, what did you see under the valve covers?