JIM, at the risk of being rather wordy. In 2000, when leaded fuel for cars
throughout Europe became illegal to sell, the collector car fraternity over
here went into headless chicken mode. I was at BMIHT at the time and spent a
lot of time talking to MG Rover Engineering for guidance info that the Centre
could impart to the thousands of clubs across Europe who were asking us for
guidance. At the time, MGR still had cars circulating around the world whose
engines were not originally designed for unleaded fuel and dealers wanted info
too.
The guidance we received was:
1. Have the cylinder head reworked to have hardened exhaust valve seats fitted.
This was the most expensive option but for many was too costly if the car was
being used for weekend summer trips and would probably do no more than two or
three thousand miles a year.
2. If new exhaust valve seats fitting was not an option, retard the ignition
and use either Castrol Valvemaster or another potassium based additive. Our 95
octane unleaded is roughly the same as your 91 octane (you calculate octane
values differently to Europe) and you could also consider giving the tank an
octane booster at each refill. We also have a 98 octane unleaded too which was
recommended over 95 but still with a potassium additive.
3. Rely on â??lead memoryâ??. MGR maintained that previous prolonged use with a
leaded gasoline left a long term lead deposit on the valve seat which would
last for a long time if the engine wasnâ??t raced or forced to operate under
heavy load, thereby indirectly saying just retard the ignition and be gentle on
the accelerator. This applied very much to the old A and B series engines found
in old Mini, Spridget and MGB.
Personally, I never bothered to put hardened seats in either of my two Triumphs
and never noticed the valve clearances closing up over about ten years use
before I sold them. I just put in Valvemaster at every refill. Weâ??re now 21
years down the track with unleaded only and there are still thousands of
ancient and venerable cars on both sides of the pond whoâ??ve had an unleaded
diet without an additive and appear none the worse for it. However, what does
concern me of late is the rapid escalation of ethanol in modern fuel and the
hell it can wreak on fuel lines, pumps and diaphragms in alleged short order.
In summary, just retard your ignition a bit and use a potassium based additive
and I donâ??t think youâ??ll need to worry. Iâ??m confident youâ??ll receive
many replies with variable views so apologies in advance for any confusion
caused.
Jonmac
Vote for Guy Fawkes! The only man who entered Parliament with honest intentions.
> On 17 Mar 2021, at 12:16, Jim Henningsen <trguy75@gmail.com> wrote:
>
> Whatâ??s the wisdom on using lead substitute in gas for triumph four cylinder
> without modifications for unleaded head. Use, donâ??t use? I use the
> Valvoline racing oil with zinc in the engine.
> Thanks,
> Jim Henningsen
> Ocala fl
>
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