The V8 Owners Forum -

Hope this helps you find out what your heads are guys, the identification marks are in the rocker area in the centre of the head,
-----------------------------------------------------------------------------------------------
1976-87 SD1 production for twin SUs (carbs in general), all V8s from the introduction of the SD1 took on the new specification cylinder heads. They incorporated larger inlet & exhaust valves as well as revised combustion chambers (36cc), taking a 19mm reach spark plug. Anything with a V8 between these dates should have this spec. The SD1 also introduced inlet valve umbrella oil seals, simply a nitryl washer which is pushed over the valve stem before fitting the spring and retainer. These seals often breakdown under the severe environment inside the engine and disappear altogether!
Casting Numbers: ERC 0216
-----------------------------------------------------------------------------------------------
Efi. On introducing fuel injection a small cutout was ground in each inlet port to clear the injectors, as Efi was introduced with the vitesse, the heads also incorporated flowed valves; with a 30° back cut and wasted stems on the inlet valves, very different from the standard SD1 type. As the SD1 was phased out of production, the Range Rover was just going over to Efi, thus all V8s after this date feature virtual vitesse spec Efi cylinder heads, including the first 3.9s.
Casting Numbers: ERC 0216 (note: As SD1 type, but machining process differs from traditional SD1).
-----------------------------------------------------------------------------------------------
Early 90's. Here comes the confusing time period. It seems sure that all V8s now had vitesse valves, as after 1993 Efi became standard. In 93 or just before, the valve guides changed to the modern cap type (blue), one for each valve, all V8s took on this feature yet the casting remained as per vitesse. 4.2 Litre motors however also had factory standard vitesse heads, but during production Rover switched to composite gaskets, whilst retaining vitesse heads. The heads were machined to bring back the required compression, the same thing happened to the then current 3.9; you may also see some 4.2s with only 10 head bolts, the outer 4 holes through the head being plugged, these are the composite gasket units.
Casting Numbers: HRC 2210
-----------------------------------------------------------------------------------------------
Tempest and Thor. With the introduction of the new Range Rover in 1994 a new head was brought into being, with a revised casting (No 2479) the head had larger ports than the vitesse heads but retained the same valves and guides which were present from ~1993 onwards. The combustion chamber volume (29cc) was also reduced (by simply machining off more material on the face) to compensate for the increased thickness of the composite head gaskets and probably most noticeable, the 14 head bolts were reduced to 10, the 4 outermost being removed. Incase you're told otherwise, 4.0 and 4.6 litre heads are identical.
Casting Numbers: HRC 2479

Very useful Tony.
I have just found the heads I bought are in fact 4.6, which is what I wanted.

nice one

On the latest 2479 heads, will the mounting lugs for ancillaries like the alternator etc all be the same... ie if I find a set of flowed/big valved 2479s, will they just interchange? I'm guessing so but conf would be handy

I'm sure I've seen another casting. It was from/for a tvr and the inlets had a higher ported port then 'normal' heads allowed. Downside is my friend has this ported head and has never found another to match it. He bought it at an autojumble.

I've been given a set of HRC2479 heads and i have a 3.5 P6 engine my friend wants to rebuild.......will they be useable or are they just for 4.0 engines and up and if they are good are the accessory holes the same as the earlier heads.........i presently have a 3.5 with 3.9 heads on it

its probably a bit late now but are the early heads ( 1986 ish ) ok with unleaded fuel ?

bodger wrote:its probably a bit late now but are the early heads ( 1986 ish ) ok with unleaded fuel ?

I've been using a set of 82 SD1 heads for 11 years now. The last five with big valves. I recently stripped them to modify the valve gear & except for a cleanup the seats were fine. No sign of recession & all I use is Super Unleaded.

Regards Ged

Mine don't have any casting numbers on, suppossed to be 3.9 heads. They have the little bit cut out as per efi but then so do some 3.5's. How can I tell what they are? I was led to believe the 3.9 had slightly bigger valves, is this true?

newbie question

I have a very late p6b (build date is early 1976 NZ assembled car)

It's got 9.25cr heads on it.

Down the track I know the engine is going to need a freshen up.

Do I bother having the original heads cleaned up and fitted with hardened valve seats or do I just go straight for a later head type (ie SD1 heads)

I want to keep the original 3.5 block, but get a little bit more performance along the way

Also, if I manage to find a set of tubular extractors/headers, are the exhaust ports the same or do p6 head exhaust ports differ from SD1 ports etc etc

Hi
If you have P6 heads then SD1 heads will out flow them nomatter how much porting you do to the P6 heads, further a quick basic clean up and open out of the valve seat insert, with a 3 angle seat job will give you about another 15% flow over standard SD1, well worth having. Unless you desperatly want originality the SD1 heads win every time.
Mike

Hi mike

that's what I gathered from my reading, that you can spend a truckload on the p6b heads and you'd still be behind.

second newbie question, will the p6b rocker covers fit on SD1 heads?

My engine is from a '72 P6, briefly whats the difference between SD1 heads and mine? I'm not looking to change the heads, just curious in case any turn up dead cheap so I know if its worth buying them - do you notice a difference in performance or economy if you just change the heads with no other tuning mods?

ratwing wrote:My engine is from a '72 P6, briefly whats the difference between SD1 heads and mine? I'm not looking to change the heads, just curious in case any turn up dead cheap so I know if its worth buying them - do you notice a difference in performance or economy if you just change the heads with no other tuning mods?

The SD1 engine brought the output back to what it was on the high compression P6 engine, but without needing 100 octane petrol - more or less. Mainly down to the heads.

That was really an useful information indeed and i was willing to know about the cylinder heads,That would certainly add to my knowledge and would like to implement it as soon as i can.