MG Car Repair: Unleaded gas, valve seat recession, stelite

Question
I bought a 1974 MGB new and drove it for 14 years on gas available at that time.  I recently bought a 1970 MGB and am now concerned (being older and wiser) about the use of unleaded fuel in this automobile.  What are your thoughts on this?
Thank you,
James Blackledge

Answer
Hi James,
You must not be in the US as that is all you can get in the US now is unleaded. The lead in gas was put in to raise the Octane rating because the oil companies didn't want to refine the fuel enough to get a good octane rating of the gas and the ONLY side benefit I ever seen was the lead acted as a lube to ease the valve to it's seat (since it is not possible to have a valve guide so tight as to guide it straight to the seat)
At first when they removed the lead they had nothing to act as a lube and we had valve seat recession on the normal seats so engine manufactures started installing hardened seats and stelite on valve faces. All through at this time Amoco high test (called White gas) never had any lead and all of us who used it never seen any valve seat recession on the non hardened seats. So they must have had some other lube in the gas. I think many of the unleaded gas companies today have an additive to act as a lube but you would have to contact the one you prefer to confirm this.
I once seen a picture of the combustion of unleaded gas sold by Amoco and gas sold by other gas companies at the time before they added the lead. The Amoco flame was smooth and round where the other gas was a jagged flame with spikes and when the lead was added it cut down some of the spikes but not by much. These spikes were extremely hot and the uneven burn was not what an engine needs. This partially explained why all of my customers with E-Type Jags running on Amoco white gas were ALL out performing the Jags running on leaded gas no matter what the octane rating was. Back then gas stations in my area (Jax FL) were tested each month for octane rating and Amoco was many times found to be lower than their competition. For example Richfield advertised 100+ octane and Amoco (from the tests were as low as 80+ octane at times)yet the Amoco always out performed in speed and fuel mileage the Richfield gas used in the Jags. The E-Types in the US are 9 to 1 compression ratio normally. I don't know what Amoco (BP today) does today but back then it was tops as far as I was concerned. A side benefit I noted in the dealership was a lack of exhaust repair and a longer engine life from Amoco users. This included MG, Triumph, A-H, Sunbeam, Lotus and Alfa Romeo cars we were dealers for.
I see absolutely no benefit from using lead in gas to correct an engine problem. I say use a better fuel and correct the engine you will be far better off.
That is my soap box speech for the day.

Howard