Valve size

[Briefträger]

I have been offered a pair of heads (Chimaera 450)which I have been told yhat they have larger valves than the ones in my HC anyone know if this is a fact or fiction, They are cheapish and if I can get a bit more power then that must be good

[Bomber Denton]

I thought the HC head was a reworked item anyway? I have a feeling the big jump comes with the 500 heads at these have the biggest vales and three way valve seat angles.
I personally wouldn't bother, firstly you want to be checking compression ratios etc then you shouldn't fit a second hand head without pressure testing etc which adds to the expense.

There are far better mods to go for first for similar money but if you do have a head/gasket problem I would personally recondition the ones you already have. For modifying heads speak to TVR Power.

[v8 racing]

The 450 chimaera heads are completely standard range rover items no better than what you have

[Briefträger]

Ahhh thought it seemed to good, what are the standard sizes, are these 'Vitesse' heads, would Chim/Griff 500 heads be better bet?

[markh]

Dom at TVR Power told me that all 450's had big valves fitted as standard, so are thses the same as 500 heads?

[v8 racing]

I think dom must have meant the early 450 as fitted in the wedges and very early griffs, the 450's in the chims definetly had standard heads other than being fitted with double valve springs

>> Edited by v8 racing on Friday 2nd December 18:03

[v8 racing]

They are the same size valves as the vittese head, but do have fractionaly bigger ports to them and smaller combustion chambers, the 500 heads are much better in stg form so to speak the 500 would be a stg 4 from most after market rover tuners

[jonnyb]

So is there any point in putting 500 heads on a 450?

[v8 racing]

yes absolutely potentialy they will release a good 30 bhp on a 450 engine, on the inlets you are going from a 1.57 to a 1.69 inlet and 1.35 to a 1.46 exhaust valve with fully polished and ported ports

[markh]

v8 racing said:

yes absolutely potentialy they will release a good 30 bhp on a 450 engine, on the inlets you are going from a 1.57 to a 1.69 inlet and 1.35 to a 1.46 exhaust valve with fully polished and ported ports

Rob, would it be possible to upgrade a pair of 450 heads to 500 spec heads or is it better (cost effective) to find a some original '500' units?

[macdeb]

markh said:

v8 racing said: yes absolutely potentialy they will release a good 30 bhp on a 450 engine, on the inlets you are going from a 1.57 to a 1.69 inlet and 1.35 to a 1.46 exhaust valve with fully polished and ported ports Rob, would it be possible to upgrade a pair of 450 heads to 500 spec heads or is it better (cost effective) to find a some original '500' units?

Would also like info' on this. Cheers.

[v8 racing]

The cheapest way would certainly be to try and find some second ones, obviously just make sure they are in good condition though, the actual porting of the heads is only a fraction of the price the main costs are the valves and seat cutting so if you will be needing to do this walk away from them! basically we could offer two types of heads a stg3 and stg 4, the stg 3 will match the tvr heads with the added bonus of more port velocity low down so you end up with a much smoother engine and a bigger spread of power these retail for £850 now, the stg 4 the same goes for the spread of power you just get more having been fitted with larger valves than the 3's, the 4's have the same valves as the 500 heads which are 1.69 inlet and 1.45 exhaust, the 3's have 1.64 inlets and 1.4 exhausts

[precat]

Hi Rob
Please clarify. Price quoted for stg 3 heads £850, is this plus VAT? What is the price for the stg 4 heads with VAT.
Thanks

[v8 racing]

Sorry precat yes it is £850+vat for the 3's and £1100+vat for the 4's