[TR] Lead substitutes

[John Macartney]

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 ‘lead memory’. 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 wasn’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. We’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 who’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 don’t think you’ll need to worry. I’m confident you’ll receive many replies with variable views so apologies in advance for any confusion caused.

Jonmac

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> On 17 Mar 2021, at 12:16, Jim Henningsen <trguy75 at gmail.com> wrote:
> 
> What’s the wisdom on using lead substitute in gas for triumph four cylinder without modifications for unleaded head.  Use, don’t use?  I use the Valvoline racing oil with zinc in the engine.
> Thanks,
> Jim Henningsen
> Ocala fl
> 
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