The V8 Owners Forum -

I have seen reference to the above being possible and even potential performance upgrade due to the larger ports, but not found much that is definitive. I'm am looking at this option for two reasons i) Long term I would like to have the new style valve stem guide seals ii) If there is a potential performance gain then better to get the 4.6 heads and refresh those than spending the money working mine

Naturally I don't want to reduce compression so would I need to use the composite gaskets or the older style ones? I understand the 4.6 heads have a smaller chamber due martial being removed from the face at the factory.

Later 10 bolt heads would increase the compression - probably what you meant to write - composites reduce it back to stock. There can be small gains as the castings are better but not significant.

They'll definitely fit. Use the stretch bolts and composite gaskets.

I am pretty sure that the ancillaries will also fit OK, although you might have spare holes as I think they went to 4 fixings at the ends (or at least at one end!!)

Chris.

ChrisJC wrote: ↑

Sun Jul 22, 2018 7:55 pm

They'll definitely fit. Use the stretch bolts and composite gaskets.

I am pretty sure that the ancillaries will also fit OK, although you might have spare holes as I think they went to 4 fixings at the ends (or at least at one end!!)

Chris.

Thanks Chris - ancillaries not a problem as I don't have any bar the alternator

I had SDi heads on a 4.6 block,so can't see why you can't do it the other way around !