Like I said the Dev engines mainly dropped valve seats but Ford decided the potential warrenty risk was acceptable. Oh and don't let them overheat as No3 cylinder goes egg shaped and pinches the rings
Apart from that they were good enough for Cosworth to base the 'BOB' on
I prefer the DOHC though the 16 valve ones in the scorpio's
though even they liked munching there timing chains when the plastic guides wore through
BV