Petrol rating

[kirky]

Hello everybody,
I'm a newbie to this forum, and thought I would ask a question.

Back in the 70s, I owned a P5B, a beautiful car. I'm due to retire quite soon and I am seriously thinking of buying another.


One thing puzzles me though. I seem to remember that my Rover needed something like 5 star, 105 octane petrol, is this still available? What fuel does everybody use in their P5Bs these days?

Many thanks.

[Smallfry]

Hello John....Welcome to the forum.

You cannot get five star any more, it was withdrawn in the late seventies or early eighties.

Nowadays you can either.......

Run them on standard unleaded and retard the ignition timing a little. Eventually it may, or may not, ruin the valve seats, in which case you either have the heads converted to harder seats, or swap the heads from a later vehicle.

Or use standard unleaded with a lead substitute additive, but eventually the above may again apply.

Or track down some proper lead additive (called tetraboost) but this is expensive.

Or Have the heads converted in the first place and use unleaded with no worries.

Or again, swap the heads from a later vehicle which (alledgedly) will also run with no problems.

Hope this helps. most popular is option A !

[dorsetflyer]

Or you can use Superunleaded, like Shell Optimax which is 98 octane and add Castrol Valvemaster Plus which as well as replacing the lead for the valve seats puts up the octane to 99.
There are many options available, and certainly my cars are happy with that arrangement, and give no trouble over the mileage they do each year.

[kirky]

Thanks for the welcome fellas, and thanks for the info Smallfry and Dorsetflyer. Wow! I had no idea about the additives, or the alternatives. Things seemed a lot simpler in my day.

I really fancy another coupe. I might be nearly 60, but I still think the coupe is a stunning design. I've had all kinds of cars over the years, including a Jag and a 5.7 Chevy Dayvan, but every time I see a P5B coupe, I still stare at (and so do other people). It was such a comfortable car, and it could move too.

Thanks again for the information, I will have to search out the additives now, and check on limited mileage insurance before I make a final decision.

I presume most parts are still available?

John

[Phil Nottingham]

I and a lot of others do not bother with the additives and apart from retarding the timing up to 6 deg nothing else need be done.

Any so called lead memory would have long gone on my cars and I have not heard of any valve problems on V8's anyway.

It will go better though on 98 or 99 Octane (from Tesco) if you can obtain it or afford it

Parts are readily obtainable and P5 ownership is a real viable option especially if you can do some work yourself.

Go for it and welcome to the forum ;D

NB I recommend you join the club as well

[dorsetflyer]

Yes, I have had reports that the V8 would probably go on for at least another 30k just using unleaded petrol. In a lot of owners cars that would amount to 10 years of motoring before you had to think about doing a re-build.
This came from a man who is more used to early 3.5 Range Rovers.

[Geoff Arthur]

Hi, I have just used normal unleaded and Millers VSP which has been tested to work by the FHVC plus it boosts octane. If you still experience pinking you may also need to retard the timing by up to 6 degrees but try it a bit at a time because I did not need to move mine much. The above was in my unmodified car. My moded car has later heads with unleaded seats and bigger valves. It runs on cooking unleaded but loves super and goes like a banshee on it. Well worthwhile doing the mod once you are in the mood.

[Smallfry]

Most parts you are likely to need are readily available, although some are more difficult and expensive, so no real worries there.

Go to a specialist insurer for a sensible quote. If you have a decent claims record, an elderly gentleman such as yourself should not pay much more than around £100 or so per year.

[keith]

I anyone is interested I've just picked up my car from Richard Giel and he is selling a stunning J reg coupe, white with a grey roof. Present owner has had car since it was a year old. 60K miles on the clock and an interior which looks new. I think he wants £8000 for it.

Keith

[lagain]

As the V8 has alloy heads it already has hardened inserts. Time will tell if they are hard enough,

[kathandsun]

Check out Rimmer Bros V8 Catalogue and spend a lot more time with RPI web site - loads of useful info. SD1 or later heads have a 2mm larger exhaust valve, this disapates heat better - thus copes better with unleaded. Fit the heads with a thicker gasket and then the 10.5:1 compression ratio the P5B engine has will be reduced - again helping cope with lower octane petrol. The better flowing SD1 Head makes up for power lost by reducing compression.
PS I have read all this and never put it to the test!
has anyone got experiance of the above mod???

[Deleted]

I have just carried out the mod to later heads, in fact I have used late 80's Range Rover EFi heads. The only difference I know about with EFi heads are the small cut outs in the inlet ports to allow for the fuel injectors to spray out an even pattern. The mod is very straight forward with no hidden problems, but RPI do recommend you use the composite head gaskets wich are thicker than the tin ones, the main reason is that without lowering the compession slightly you may well have pinking problems that you can't eliminate. The car does seem to be more responsive, the only problem I have is that the tick over is not quite so smooth but a bit of fine tuning should sort that out. Can't comment on fuel consumption yet as I have only just completed the mod & have not given the car a decent run yet to check it. The heads that I fitted, which are new & left over from my days wheelin n dealin in Land Rover parts where actually from a now closed dealer in Saudi Arabia & where listed in the parts book as Export Only Low Compession 3.5 EFi Range Rover Heads. Anybody any idea what the difference is in either low or high compression heads. A warning to any one using a SD1 inlet manifold on a car which has the later short kick down cable fitted to bracket at the rear of the cylinder head & that is that the casting that the linkage rod goes through is approx 8mm higher than on the standard P5b manifold so will not line up correctly with either the carb linkage or the kick down bracket without some very fine & acurate alterations.

[Deleted]

As someone who uses my P5B coupe every day to go to work, I do get through quite a bit of petrol (when the d**n car is working, it's broken again!)

I have unleaded freindly heads fitted, so no concerns about valve recession. But, while the engine runs happily of 95 unleaded, it runs better on one of the many vaireties of super unleaded 97 to 99 octane.

[dorsetflyer]

That's interesting as my Humber Sceptre has an unleaded head fitted and while it runs OK on straight unleaded the engine runs better on Super-unleaded.

I have seen an article on this somewhere, and the advice was to fill up with Super every now and again.