A wonderful question to ask after 50 years of iron heads!

915 67 big valve heads are top of the 440 tree in my mind.
906’s are very over rated and 452’s are better...

But it’s 2021 and aluminium is king now!

Better ports, less weight and affordable.

Me I would spend 100 hours porting each 915 head and be very, very happy to do so... drumhit

Do I need hardened seats, not for the 1/4 miles I do lol...
Do they need a skim every time I take them off?
Not really...

Had a pair of 452 MP aluminium heads to repair and they were Awful.
One head was bowed 0.020 thou that’s 0.5mm... fan

The work needed to put it right was crazy... sawzall

Last edited by Gtxxjon; 03/02/21 08:42 AM.
Carpe diem, quam minimum credula postero, thanx Horace!

There’s no point trying to fix stuff that ain’t broke,,, 'but if ain’t broke',,, you is not trying hard enough...