Couple of questions for you.

What is your valve clearance set at?

The slapping metal noise leads me to a sticking valve or bucket (more so the valve sticking). Did you have the guides changed out when you had your head ported? What about a valvejob.

To be honast i would suggest stop driving the car. if you do have tight valve guides than the likley hood of one breaking is very high and that will turn your motor into spaghettios .

 

I have the exact ticking sound coming from my stock long block engine.

The motor has been ticking like this for 5,000 miles and making over 400whp.

I am starting to look into the issue as well. First i would check valve clearance as Greg from GSC suggested.

If i discover what causes the problem before you i will pass the info along.

 

The head was built to spec at a machine shop and ported. I will see if I can get my builder to chime in. The car was actually initially quiet upon first start up. I then started hearing the noise a day after.