THE INTERNATIONAL JAGUAR 'S'-TYPE REGISTER FORUM

[quote="Glyn Ruck" post_id=5797 time=1586902622 user_id=175]
The unleaded fuel issue is quite a different matter to alcohols in fuel. Valve seat recession with unleaded fuel was only really an issue with cast iron cylinder heads with no separate seats but the valves seating straight on the cast iron.

I believe the three BMC A series engines I run and the XPAG engine in the MGTD have valves running directly in the cylinder head and for me still no trouble in operation since 1975 when unleaded was introduced here in the USA. But like I say, I do not run these cars flat out all the time.

What mileage do you do? The valves usually start lifting pieces of cast iron out of the seat leaving deep pits without leaded or the use of LRP gasoline. In my long oilco career I've seen plenty of those heads ruined & valve clearences closed up to zero until they burn.

You must drive these cars very gently.

Well following up: the Austin, in my ownership since 1971 has 108,000 miles and the head has never been off. The 1960 Morris convertible 48,000 miles without head removal. The MG since my ownership, 25,000 miles without head removal.

You are obviously being gentle with them & not running for extended periods at high RPM. I do accept that us technical oilco folk see a concentration of issues because people approach us only when they experience trouble.

It is something I point out to our members at MBWorld where I'm a mod & ambassador. Forums concentrate problems/issues because many people only post for advice when they have trouble.