Unleaded valve clearances

[Mike Wattam <MikeWattam@domain.elided>]

Hi Ian

I read your write-up also in another magazine.

Please do not forget the 'memory' effect of having used unleaded in the
past.  It is believed from experiments caried out on aircraft and marine
engines, that this 'memory' can last for up to 5,000 miles if the car is
not driven hard.  I am not surewhether your engine has been built with new
valves/re-ground seats or what, can you enlighten me please?

If there is a 'memory effect' present, may I suggest you do less short term
checking which will probably be fruitless as I would in any event expect it
to show no change, but more in the longer term.

My own Stag has been running on unleaded but unmodified for over 6,000
miles now, and no ill-effects.  I have used the car hard, so I would really
expect the 'memory effect' to have gone by now.  I checked my valve
clearances at 5,000 and no discernable difference was seen.  

The valve clearances really need to be checked with each cam on its base
circle, when this job becomes very time-consuming. 

IMHO - Mike Wattam
Chairman - Triumph Stag Register