Converting marina 1300 to unleaded

[bmcecosse]

The later 'economy' versions were definitely 10.3:1 - had flat top pistons (now much sought after I discover after giving away two engines !!). I suspect the ignition timing was heavily modified to suit - the camshaft was also improved with more lift - and they go really well, except they are hooked up to a really high final drive all in the search for best possible economy.