Hi guys I have stud mount trick flow 1.72 rockers. I want to replace the 1.72 yells Terra ones on my au220 heads. Is it a simple swap out or do I have to drill and tap for the studs.

I'm only asking as my heads are away getting checked out

To fit those rockers you will need to machine the heads for screw in studs and guide plates. You will also need to buy hardened pushrods and new rocker covers to clear the stud mount rockers.

If there is nothing wrong with the YT pieces don't bother with the effort or expense. That cash would be better put towards some alloys.

yer, like AFR 185 outlaws