V8 Heads - Any way to identify source?

I've been given a pair of Heads for a 3.5 V8 along with the gubbins that came with the eninges I bought for Percy.

Both complete engines are SD1 type 3.5's on carbs. In the gubbins though is a Rangie Manifold and carbs amoungst these spare heads. Is there an easy way to distingish between SD1 heads and Range rover heads and would there be any advantage if they were Range Rover heads in fitting them.. such as being able to run unleaded etc etc. I'm not 100% but weren't SD1's only runnable on Leaded fuel... then again I've a niggling doubt because if it's an alloy head then surely it much have some valve seat inserts anyway.

See now I've confused myself ;-)

Lee D

Reply to
Lee_D
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The SD1 was runnable on unleaded I'm sure. Better let someone who knows for certain, but I'm 90% sure they could. I know the Vitesse version could as we used to work on them & remember putting unleaded in. Mind you that might explain the constant return of the thing for repair!

Have you tried the rpi website to see about identifying the heads?

Nige

Reply to
/\/ / & E

"Lee_D" wrote in message news:thrMd.509$ snipped-for-privacy@newsfe2-win.ntli.net...

Lee, all heads from SD1 onwards (easily identified by having the single valve springs and long-reach spark plug thread length, earlier heads had twin springs and short-reach plugs) will run unleaded ok. Don't be taken in by fancy advertising and claims by some of the so-called $pecialists, they are only trying to empty your wallet in their favour. Pre SD1 and very early rangerover heads need harder inserts, but not the later single-spring type. The early heads aren't all that good anyway, having slightly smaller valves. SD1 and carb rangerover had the same heads, with the SD1 vittesse having the valve heads recessed further into the heads and waisted stem valves. Some EFI rangies also had the waisted stem valves, but not all!! EFI heads will fit straight on, and are easily identified by a small curved cutout in the roof of each inlet port (clearance for the injector nozzle spray pattern). Later heads have only 10 bolts to bolt them down with, and are machined to a shorter overall height to compensate for the thicker composite type head gaskets, these heads are about the best standard heads there are, having slightly larger exhaust ports. Don't worry about the outer row of 4 bolts being missing if you get a pair of these heads, they are a waste of time. See Rpi's website for a good reason why, I cant be arsed typing it all out right now! There are variations between number of bolt holes in the head ends where the lifting brackets etc fit on, there are 3 and 4 bolt variations and different thread sizes as well, but all are UNC threads. Badger.

Reply to
Badger

Badger,

Many thanks, Thats put my mind at rest! Looks like I've a new pair of paper weights :-)

Lee D

Reply to
Lee_D

In message , Badger writes

I did lots of research on leaded/unleaded many moons ago and I beg to differ on that point. The only problem with pre-SD1 AFAIK is with the high compression engines pinking on unleaded - all 9.75:1 and below should be ok, composite head gaskets may pull compression down far enough above 10:1 (better to gas it instead!) but all valve seats are hard enough for unleaded. Then of course for low down grunt small valve heads have their place ...

Reply to
AJG

"AJG" wrote in message news:iW$ snipped-for-privacy@shedcity.demon.co.uk...

Ok, I am not going to disagree with you re. the octane issues, however I have stripped plenty of early engines and found a considerable number with severely burnt and pitted exhaust valve seats - this I have attributed to a different spec of iron for the seat inserts, and my local engineering firm that I use for all my work agrees with me. That's not to say that we are right of course, neither of us have paid for expensive metallurgical testing. Do you have access to any test results? I'd be very interested to see the data if possible? A lot of engines that allegedly need 4* (landrover 2.25 is a perfect example) will run on unleaded ok for tens of thousands of miles with no issues, especially where they are used relatively gently and not at high rpm high load conditions. Some engines will burn valves even on 4* if driven hard all the time (leyland B series, for example) and some that allegedly require super unleaded will run just fine on normal unleaded if the ignition timing is backed off a couple of degrees (Jaguar 4.2). FWIW, some years back I built a 3.5 using 10.5 P6 pistons in a stiff-block, with composite gaskets but with the SD1 Vitesse heads skimmed to maintain overall compression, fitted with a high-torque cam, it ran 6 degrees more advance at idle, 4 degrees less total mechanical advance, and hit full advance by 1500rpm! It never pinked once, running on unleaded fuel. Pity the motor wasn't on gas back then! As for the smaller valve sizes, all other things being equal they will increase gas velocity (at a given rpm / depression, within limits) but in the case of the Rover V8 engine the ports themselves on these early heads are a poorer design with less swirl effect to the incoming charge, so the overall scavenge effect is actually better with the larger valves. Do not be fooled by misleading power/torque figures given out by the factory at the time, they were prone to exagerate!

Badger.

Reply to
Badger

Badger, I'm a bit confused (easy, I know)...

Without taking the rocker covers off, can I tell whether my 1975 range rover V8 engine will run unleaded, since that's what I've used since I had the engine fitted. It's engine number is 35900537, (8.251CR) according to the plate, and it uses Champion RL92YC plugs, I'm told.

Regards, Danny

Reply to
Danny

Pull a plug and see if it's short reach or long reach. If long, it'll definitely be ok on unleaded, if short, then personally I'd say no, but there are those that say yes. The numbers you quote suggest early heads with short-reach plugs. If it's been running on unleaded ok for a considerable mileage, then it should hopefully be ok. As I said earlier in this thread, there are engines that are definitely leaded fuel engines that people have reportedly run for thousands of miles on unleaded with no issues. Basically, it's your choice. Badger.

Reply to
Badger

On or around Thu, 3 Feb 2005 23:04:00 +0000 (UTC), "Badger" enlightened us thusly:

never noticed any problems with 10.5:1 (theoretically) P6 engines on LPG. OK, there were problems, true, but never noticed any valve seat problems.

Reply to
Austin Shackles

In message , Badger writes

I'd have to look up references - it's a looong time ago! However the largest (there were more but it was primarily one) original manufacturer of the valve seats supplied to Rover stated that their seats were identical material to the piston rings - which was actually harder than some 'hard' valve seats! This does not preclude of course later replacement seats , a few of the 'other' suppliers offerings or of course just high mileage, imperfect mixture/timing control on whatever fuel ...

Reply to
AJG

Interesting, thanks Andy. Badger.

Reply to
Badger

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