head torque on 420
 

What torquing method is best? I have read about two methods. One is to torque both heads to 30nm ,after 30min go to 60nm. The other method it to torque to 30nm,60nm 30min. then back off each bolt 1/4 turn and go back to 60nm [in proper order]. Also what method should i use to clean out head bolt threads?

Can anyone help me with this?

I had good luck on my 380 by covering the cylingers with circles of manila folder and a narrow overhang of masking tape (use a drafting compass to draw circles of correct size). Then use a nylon rifle bore brush ( do not use steel, bronze or brass...they chew up too much soft aluminum thread). Also, do not use a tap to chase threads as this, too, will chew up way too much thread. After you run the nylon brush up and down using an electrice drill, take an air hose and blow out the holes. Take a good wire brush to the bolts and then lube the threads with motor oil. Torque as you suggested and backing off 1/4 turn and then retorquing, ONE bolt at a time. As mentioned, I had good results using this method.

Thanks for the info.I will try to find a nylon brush.Great idea.

Before you bolt down, dip each bolt in a little oil. This will keep it from catching on those clean threads.

We usually spray an alchohol based cleaner in each bolt hole then blow out with air.