nigecapri wrote:Off with the distributor cap & check the copper/alloy segment for #3 lead is in good condition - scraping clean if claggy should help but new cap is best, also check the shaft for sideways wobbles - badly worn can give a poor spark for one plug. If no improvement then just fit one new plug in #3 and test it for improvement. If no change then get a replacement HT lead for #3 & test.
I stripped and rebuilt the head for James middle of last year due to other problems but it was rebuilt with top hat valve stem oil seals etc. The distributor is fitted with an aldon igniter type electronic ignition and the shaft is OK (dead steady pointers with strobe on it) and the cap and leads were new.
James has fitted a new set of plugs which have cured the running issues but when the head was off we noticed that the bore on no3 was slightly scored which is where the oil contamination and burning must be coming from. Compression was still OK Just for now he's going to run the car as is whilst it runs OK with no smoke coming out or heavy breathing, just keeping an eye on the plugs, but long term a rebore is on the cards.