Changed Timing Belt, now Knocking...???

I just changed the timing belt on my 91LX. I lined up the cam and crank gears, checked it about 10 times now. Its a DIS car, but I lined up the auxiliary shaft gear anyways.

Got it all together, started right up, but there's a loud knocking (more like a tapping) under the valve covers. WTF? Wasn't there before.

Tore it all down, just leaving the exposed timing belt (and had a battery charger standing by). Still knocks under the valve cover.

I don't get it, what could changing the timing belt have done? I thought these were non-interference engines, so valves shouldn't be tapping even IF I weren't lined up, right?

Any ideas?

Yes, thank you for the response.

After much research, I discovered exactly what you posted. Against that gut feeling in my stomach, I drove it. Went away once the engine temp started to rise.

I'll try it again tomorrow after a full cool down, but I now have high hopes.

Other than that, timing belt change went without a hitch (except for that damned crank bolt).