petrol

[g4pyd]

Hi,
I wonder what the members use for petrol these days?

unleaded with addatives?

unleaded without addatives?

and what addative if used,


Colin @ Grimsby

[Ken Martin]

I use unleaded petrol with Castrol Valvemaster Plus additive (rather than the standard one which I tried initially). I have experienced what I think is knocking or pinking on full advance since the loss of lead. This may be due to the chemistry of the modern petrol or the fact that my engine is tired out and making knocking-like noises due to mechanical cries for help. Also I have recently enjoyed stereophonic hearing via NHS digital hearing aids. (I generally switch them off when in my Minor to save worries about mechanical noises, but often Kate is with me and so I an expected to have them on).
I do believe that the modern petrol has an effect on the amount of advance in general use. I have to retard the ignition more often now especially on hills. I have experimented with the top Shell petrol – the name escapes me. It shouldn’t be necessary to use anything other than the lowest octane petrol available in such a very low compression engine, but, unless I was fooled, the engine did seem to run better with this higher octane fuel.
Unless you expect to live to a very old age and use your Minor on motorways regularly at 55 to 60 mph doing tens of thousands of miles – I don’t think it is worthwhile having hardened valve seats fitted – the Castrol additive has been proven to work OK over thousands of lab test miles in BMC A Series engines.
Ken

[DF9053]

I just use unleaded without anything. I don't get the pinking that Ken describes not even on hills. These are both ohc cars.

My understanding was that lead was only introduced into petrol in the late twenties anyway, and as Ken says the compression ratios are so low that pre-ignition should not be a problem. I have also run an A series engine on unleaded for thousands of miles without any problems, so this is the approach I am taking with the Minor which only covers about 2000 miles a year anyway.

Cheers
Jeremy

[chris lambert]

The Anglians had a debate about this a couple of years ago. If I recall correctly, none of us use any additives at all in our unleaded - I certainly don't in either of my engines and I pretty sure Roger doesn't in his standard engine. I can't remember if Trevor has hardened valve seats or not (hardened arteries - maybe!). As Jeremy indicates, lead wasn't added to fuel until just about the time our engines were launched, along with the car.
Chris

[g4pyd]

Hi thanks for you info,

it seems like I have made a massive mistake in thinking I had a big end gone or some other such tragedy
when I refilled the petrol tank from empty,

never mind I need the experience and stripping the engine down and correcting any minor wrongs (pun)

hopefully wont cost a arm and leg,
will keep you all posted Colin

[Toby]

I use "Tetraboost", used by vintage Bentleys for racing, it's tetraethyl lead in a bottle, toxic but it's the very stuff that's missing from unleaded! I use it every other tank and you can control your octane rating, seems fine in minors and bikes. If you use lead replacement additive it's important not to mix different makes unless you know they are based on the same compound, if you use teraboost then never allow it into the fuel of an engine with a cat-lead will wreck it.
I wouldn't use redex on an old engine but I do use it to try and slow down the carbonizing process on clean engines. It's also a good cleaning agent for carbon on engine bits.