unleaded heads for V8

[arthuy]

I am interested in finding out about V8 heads.

I am aware that are variations between the V8 engine from P5 through to current Land rovers.

What I want to check is from when did the heads which are suitable for unleaded come in to production.

I am lead to believe that the SD1 and range rovers where the first with larger valve but I don't think this happened til 1979.

Can anyone shed some light on this. When did they change? engine numbers? how to distinguish and what should I expect to pay for a pair of these heads?

 

[rovermorris999]

They are all suitable for unleaded from a valve wear point of view. Earlier engines were higher compression and thus needed higher octane fuel so unleaded was no good, but you could get round this by retarding the ignition. There was a previous thread on this which should answer any questions. The very early Range Rover was sold in California and was unleaded capable due to the low compression. The part numbers for the inserts and valves for that engine are the same as for UK cars but UK cars had higher compression and thus needed 4 and 5 star fuel.

 

[PeterB76]

All post '76 i.e. SD1> heads have the larger valves.

If you have a 10.5:1 Compression engine (Pre '73) you can fit the later heads with Composite gaskets, this gives you better sealing, breathing and a slightly reduced compression ratio that is better suited to unleaded petrol.

I would also (and do) use Shell Optimax Petrol, as its unleaded but about 98 Octane.

If you want to splash out check out RPI Engineering's website . They can supply a range of reconditioned unleaded heads, but you probably wont be able to use your old ones as an exchange due to the smaller valve sizes.