How exchangable are V8 heads?

Philippe Holland

Philippe Holland

Member
Hello,
As a way of going unleaded cheaply, can I fit a pair of known good heads from an EFI 3.5 Range Rover
to my 3.5 V8?
Cheers,
Philippe
 
They will fit, and should give you the larger valves as fitted to the later engines, but as far as unleaded goes all aluminium heads have hardened steel inserts so it's a waste of time as far as that. P6B's were exported to the US where they had unleaded long before we did. Valves used to burn out using 5*.
 
Harvey.
I remember an amusing conversation between the workshop manager and a customer at the Rover garage that I worked at during the mid to late 70`s, the owner had a P6 3500S which he used to drive “enthusiastically” everywhere he went, and the engine was consuming exhaust valves on a regular basis, every service it was necessary to have one or both heads off for work. :shock: Workshop manager suggested he bought his 5* petrol (we had 1 pump of Cleveland Discol on the forecourt) from the garage that serviced and supplied his Rover rather than the city garage where he parked it near his work.
From then on he did buy “our” Cleveland Discol 5 * with several shots of RedX UCL and never had a further valve problem ! :D
(A year later he bought a new SD1, loads of problems, hated it, and Rover lost him to Jaguar) :roll:

T`was good stuff Cleveland Discol !

Philippe sounds like a good move, nevertheless,I always use an octane booster mix in my S now as I dont consider Super Unleaded by itself up to the mark !
 
I was at a Rover dealer at the same time and we had one pump, of 5*, not for retail sale, but for customers and staff, and although we did valves, they weren't a regular thing. As we were booked up for work at least 3 months in advance we had the same cars coming in on a regular basis. You were lucky if you could actually get booked in at all, I've never known a place before or since that was so packed out with work all of the time.
 
Yes Harvey I remember those times well, working on good well designed cars. My speciality was P6 clutches, if all went well turn round - job done- was about 2 hours, book time was about a day IIRC ? Bonus time come friday ! lol
 
Thanks for the input gentlemen.
Am I right in thinking that the later heads had valve guide oil seals and the earlier ones didn't?
I have a 'S' engine under the bench and wanted to give it a partial rebuild with the RR heads, composite gaskets to lower
the CR a bit, new cam, steel timing gears / chain, followers etc.
I did a similar build on my 3.5 RR recently adding a 3.9 cam and it runs great. A new cam and followers freshens up an older engine very nicely.
It's lovely and quiet and smooth now.
Which cam do you guys recommend? Can I use a 3.9 as in my RR with good results?
Philippe
 
Hello Phillipe,

Cylinder heads made from 1993 onwards (first appearing in the 3.9 and 4.2 litre engines) feature valve stem oil seals on both inlet and exhaust valves.

If you wish to lower the compression ratio, be sure to use 14 bolt cylinder heads,..made up until 1993, and those made that year feature the valve stem oil seals. These heads have 36cc combustion chambers, the same as your existing P6B heads.

Heads made roughly from 1990 onwards also feature waisted stem inlet valves which first appeared on the Rover Vitesse. These valves improve engine breathing and are very worthwhile. Esentially them aim for 1993 heads, featuring waisted stem inlet valves and oil seals along with 14 bolt retention, perfect for lowering the CR when used with composite gaskets.

The 3.9 camshaft will certainly not be detrimental to performance in your Range Rover.

Ron.
 
Have a look at this web page it helps Identify the cylinder heads. The ancillary components have 3 or 4 bolt holes depending on the heads. Just make sure that you have the enough for your own bits and pieces.

Colin

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http://www.rimmerbros.co.uk/rimmer/rover/v8engine/heads#Cylinder Head Identification
 
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