Nothing New Under The Sun
The following correspondence from our archive between Esso and Triumph shows that the two companies were worried enough about unleaded fuel in 1970 to instigate some comprehensive studies into valve seat recession. Of course Triumphs were to run throughout the 1970's in America on unleaded fuel without problem as they do today.
If nothing else it also proves our advice since unleaded fuel became available in the UK (and elsewhere on this website), use it without modification, you will have no problems. If Esso could thrash a fresh GT6 around a test track at 100mph day after day with negligible recession then you are hardly likely to suffer any. We also have had several of our Triumph's on long term (very, very long term!) test without recession, see the Chicane and 2.5 PI MK1 pages in our museum.