The V8 Owners Forum -

just a few quick questions

1: how much can you open up the exhaust ports on the early p6 heads?

2:is it worth changing from the tin type head gaskets to the later type?

3:how much of the valve guide can be removed from the inside of the ports

if you have any pics of ported heads this would be great
many thanks mark(soon to be v8 powered)

My advice - and others will offer different !!! Oh, and all this is in the old forum archive!

Exhaust ports and valve guides - Get a set of later 4.0/4.6 litre heads with 10 fixing bolt holes - the port volumes are better as standard, the valve sizes are bigger, the valves are a better shape, the valve guides are a better shape, combustion chambers are smaller. Will save you hours of work.

Head gaskets - tin gaskets are thinner so give more compression. Both type work better if you don't use the four head bolts outboard of the exhausts ( the last four your torque down) I always trim mine back in the valley area to improve oil drain from the heads. do a trial assembly and the bits to trim become obvious.

Dave

Certainly better off with the later heads, Even the SDi heads were leaps and bounds better than the old P5/6 heads, and I think I am right in saying will run on unleaded, they have bigger ports and valves than the old heads, and for better performance go for the10 bolt heads, no matter how much you port the old heads, the standard 10 bolts will exceed the limited scope of the p5/6 heads
Ian