Inside a newly-acquired engine

[Steve Jones]

The 1998 date suggests the crank is Phoenix. I'm pretty sure the similar JB cranks came much later. At that time, the possibility of valve seat damage because of the phasing out of lead in petrol was a very big subject and I remember having hardened exhaust valve seats fitted to a block not that much later.

Steve

[David.H]

As A7 blocks pre date the introduction of leaded petrol by many many years, why did valve seats not erode "in the day".....? 
As for ethanol I recall that "Discol" I think it was claimed to have a significant ethanol content and no one worried about what it did! 
Mind you with a gravity tank is it supposed to attack steel brass, copper, zinc and solder....?

[AustinWood]

The standard Austin Seven engine doesn't rev high enough for long enough for valve seat recession to be a problem.
However the frequent decarbonising and valve grinding that was normal in the past does cause it. Modern valves and seats seldom if ever need regrinding.

[David Stepney]

I note that, at page 18 of my handbook (Publication No: 972B) the following is found:-

""Leaded" Fuels.
"The advent of "leaded" fuels (petrols containing a small proportion of tetraethyl lead) on the British market has led to a number of queries concerning their use and effect in engines.

"Provided that the same reasonable attention is given to valves and adjustments as with ordinary petrols there will be no trouble when using these fuels.

"The appearance of the valves when running on "leaded" fuel, differs from that associated with ordinary petrol, but this is a well recognized fact to which no significance should be attached.

"The deposit from such fuels can be removed by "scrubbing" the valves and their seats with a stiff wire brush of the type used for cleaning files (a file card) after which the valves can be "ground in" in the normal manner.

"We would recommend this method of cleaning for all valves whether they have operated with "leaded" or ordinary fuels as it eliminates the possibility of leaving small amounts of deposit on the valve seats which tend to cause damage, or prolong the "grinding in" process."

[Bob Culver]

Leaded fuels produced deposits which tended to prop valves open and cause failure. Narrow seats were recommended to break up the deposits. From my experience with other makes, weak mixtures and heavy valve springs contribute to recession, with or without lead. For years I ran Javelin which pocketd severely even on lead. (The horizontal engine and alloy expansion leads to heavy valve closing) I have run a 1600cc ohv Hillman for decades. Used to use an additive but too expensive. With a lot of main road running around 60 mph I get very slow recession but of just one valve suggesting mixture a major factor.
Considering many Sevens had valve grinds evry 5,000 or so through much of life, and persons used the lapping to clean up the valve, the degree of recession is often remarkably little.