I am installing the (in)famous Mitzone aluminum valve covers. I removed the improper sheet metal screws and intend to buy the correct M4 x 07 machine screws. Is retapping the threads necessary or because it's aluminum, will the new screws themselves correct the thread damage from the improper sheet metal screws?

 

Use a thread chaser if you can find one.

 

Do you have to tap? If you threadmilled you would go through less tools since you can

 

I WAS going to get aluminum valve covers. Since the screws that hold the ignition coil seal plate are questionable, I was going to modify it. After careful consideration, I decided to replace the warped plastic valve covers with OEM.