The V8 Owners Forum -

How much bhp are they worth over std, and how much less than stage 3? I may be able to get a pair which I think were V8 Developments built- std valve size but bullet guides & obviously ported... though saying all this I could probably get near it myself!!!

i may have a pair of v8dev stg3 for sale after crimbo (look in my garage post pics there) if interested,
just waiting to see if its worth getting my heads modded to what i want, or sell them and buy a pair pre done,

Is it worth replacing std ex. valves with waisted stem ones from real steel- p.n. DW555 (1.356") or non waisted stem 1.4"?

I am guessing the smaller ones are a direct replacement and the waisted stems probably have the same amount of material saved (or more) as the extra 0.044" diameter of the bigger ones gives!

If there isn't much in it I may just leave the std valves in untill I can afford full on stg 3 heads.

Secondly- would it be ok to push the guides up in a press just enough to modify the port around them above the valve area- then push them back down to proper position? This way (rather than completely removing them) I would be more confident that they would stay perfectly square when back in place...

In actual fact although narrowing the stem is good work just where it needs to be done it would no way be of more benefit than increasing valve size. Even a small increase in diameter of a modest sized valve such as an RV8 valve represents a large % increase in both valve area and more importantly "valve curtain" area. One of the main things that hold the rover back from being able to make good power and rev freely is it's small valve sizes and the difficulty involved in increasing them due to their unfortunate location in relation to bore centreline. Wasted stems is a good mod, especially in conjuction with bullet guides but increase valve size if you can.

topcatproduction wrote: Secondly- would it be ok to push the guides up in a press just enough to modify the port around them above the valve area- then push them back down to proper position? This way (rather than completely removing them) I would be more confident that they would stay perfectly square when back in place...

My dad used to always do that when porting heads - Sadly I cant remember if he recut the seats afterwards - I suspect he gave them all a 'kiss'

Cool thanks, I will try and find a valve seat cutter- RV8 heads use 5/16 stems? I may end up buying a full set of big valves and bulleted guides from V8Tuner, seems like a good price for the set plus I get the new stem seals too!

About these seat cutters- would a 1 11/16 cutter do the standard inlets ok? Am I right in thinking the inlet valves are 1.63" on EFI heads? And what size stem?

Tom,

The standard size SD1 and Range rover are Inlet 1.568" Exhaust 1.356"

Big valves are 1.63" In, 1.4" Ex.

Interestingly the standard valve lengths are Inlet 4.602" Exhaust 4.613"
the big valves are 4.595" for both so if recutting seats best to get them as level as possible

Can't help with stem size but if you check with Paul at V8 tuner he should know.

Kevin.