Cylinder head identfication

corazon

corazon

Well-Known Member
Other than larger valves, what visually determines p6 heads from later sd1/rangerover etc ones?
For instance if an ebay seller doesn't know what car they came from
I just want to get my head around the market value of recon'd/good condition later heads for future buying.
Or indeed if it's worth buying cheaper and reconditioning them myself...
Thanks all
Jim
 
P6's have double valve springs, all the rest have singles and there are various modifications and casting numbers as follows:

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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
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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).
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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
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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
 
Whoa, I never knew there were that many varieties! :oops: :shock:

More heads (albeit these are the cylinder head variety!) than Kryten off Red Dwarf! :shock:
 
Hi,
Harvey´s information was very helpful for me. I´m currently looking for a pair of SD1 heads, just to learn a little bit more about the Rover V8 and want to polish them in combination with a cam overhauling of my 9.25 P6 standard engine.
ERC0216 is clear, but now I was offered a pair of ERC0216X heads (have seen a photo of the casting no.)
I do not know, what the X means :?:
 
mtb_tuli wrote,...
ERC0216 is clear, but now I was offered a pair of ERC0216X heads (have seen a photo of the casting no.)
I do not know, what the X means :?:
Click to expand...

My immediate thought is that the X signifies 'exchange'. At some point, the heads have been overhauled and as a means of identification, an X is added.

I may be wrong, but it seems a logical possibility.

Ron.
 
The later the heads the better. No reason to specifically look for SD1 heads. RR and disco heads will be far more common these days.

The very last ones also have another advantage; they have hugely improved seals on both the inlet and exhaust (stepped ends on the valve guides). Just use the correct thickness of gasket. No need to worry about the 10/14 bolt thing either. If you need to renew the guides then you may as well go with the later types.

I have RR heads and I had these skimmed 20 thou to use the composite gasket on a 10.5:1 engine.
 
I've deliberately not skimmed the RR heads so i can lower the compression ratio slightly.
 
Thank´s all for your help. You are right, I´m looking for "post" P6 heads and as I´m not that familiar with the V8 as you guys are, I always talk then about the SD1. The seller said,they have the improved valve seals, so I think, they are RR/Disco heads. Ok, I will see, want to pick them up tomorrow. Think, I will give them away for skimming, as I will dismantle them and adapt/polish the ports and my engine is a 9.25 one.

Yes, X could be from the Xchange program, or "X" means an Xperimental head which adds 20 bhp :D
 
Never had an issue with 98 unleaded @ 10.5:1 and standard timing so can't see the point of lowering the CR which has to be worth a few BHP. The cost difference for 3000 miles a year is barely a tenner.
 
Hi, It's down to the individual engine, some will tolerate a drop of octane level some won't.

Colin
 
Ok, have got the ERC0216 heads. They look good, with new valve seals, the combustion surface is "equal", normally no skimming necessary. Guy bought it "overhauled" from the UK to repair his Ford Capri (which has a Rover heart...) but is now swapping the complete engine.
I´ve read the threads with tin and composite gasket and compression ratios.
My question (my engine is Standard 9.25:1) :
I want to use the tin gasket, do the ERC heads have the same volume than the original P6 heads, or in simpler words, is the CR still 9.25 with these heads ?
Although the heads are ok, I will dismantle them and polish/adapt the ports and let them have skimmed. Is it then advisable to take off ?/1000s also or does this effect in further adaptions to the valve train ?
I want to use the following new components :
Viper Hurricane cam / Cloyes street true roller set / cam bearing set / std hydraulic lifters / std pushrods / cam keys / preload shim kit / gasket set.
Any suggestion, what could be necessary or helpful in addition to this ? Are the bolts for the heads re-usable ?

Thanks again for your assistance :rolleyes:
 
They are a straight swap with the tin gasket or -0.020" (20 thou) and the composite. The net effect should be nil on the valve train but you should check the endfloat anyway. and shim the rocker pedestal per bank.

Anything other than a regular type of hydraulic lifter, (not necessarily and OEM one) might improve performance in a certain part of the rev range but will likely make it rattly under other circumstances (rhodes type for example). There is only real advantages here if you intend to use or extend the upper rev ranges.

I've read a lot of negatives about porting but a basic cleanup of the casting won't do any harm. I very slightly straighted up the ports as the casting as you'll know is fairly crude but you should not attempt to "port match" with the gasket as you remove a lot of material. If you were serious about this anyway you should start with the very last type of head as these flow better where it counts most (up around where the valve itself is). You could fit bulleted valve guides if you were replacing these or even bigger valves still.

Cloyes true is great. Apparently the only positive of the fibre gear is that is is very quiet - but you only get 50k miles of reasonably accurate timing.

Cams? No idea 101 opinions it depends on preference and how much smoothness at idle you want to lose. If its an auto then don't push the torque band higher. Crower do lots of grinds and are cheap. The 50229 will sharpen up the original without much compromise. The 50230 a bit more.... (have a look on V8-tuners website). It's a gamble. You may or may not like the results. What will be noticeable on any tired but sound engine is a new cam and gear will put back most of the original power, the drop off is progressive and you won't notice it until one day you'll think "didn't this used to be quicker?". If the valve timing gets late due to chain stretch or wear then the drop can be very dramatic. After your basic fueling and ignition on a sound engine, this is where to look next mostly, even a new standard cam.

You WILL need proper re-jetting to make the most of what you have done. Better flow WILL mean leaner running, especially higher up the range and you could damage your valves.

I'm sure others know more but this is a condensed form of the research I did.
 
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One more thing, -0.020 on your engine if you skim the heads and don't change the gasket will give you 9.85:1 or thereabouts. That's probably OK with 95 standard unleaded as high compression UK Discoveries ran 9.75:1 as standard. That'll buy you a few more BHP for nothing if you were doing this anyway.

I run 10.5:1 on 98 unleaded without issues with standard timing.
 
That sounds like the engine in my car...
Very smooth, very tired. The "hurricane" cam is a mild cam, I do not want to build up power at high revs or even extend the rev range, makes no sense with this car.
 
Indeed it isn't a TVR. If you want more power then a bigger, lazy motor is probably the way forward. Heads and mild cam will likely net you 20-25 bhp or so. But if you cam is worn anyway it might put back a fair few bhp you lost before adding extra. The effect will be noticeable.
 
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