Wise members of the Lancia Forum! Here are my humble experiences fixing the unstable tick over previously noted- I removed and stripped down both carburettors (Solex PHH35s) and found there was extensive wear to the carb body around the spindle shafts. The shafts are steel, running directly in the cast aluminium of the carb body. There are PTFE(?) seals at either end of the shaft and these had hardened and worn. The net result was that there was detectable wobble at the inner end of both spindles resulting in air leaks when on tick over (when the butterflies are closed).
I obtained oversized spindles (8.2mm instead of the original 8mm), replacement butterflies for one carb (as I had damaged them by snapping off a screw head) and new 8.2mm seals from Solex/Dell Orto. I found a couple of cheap reamers on the internet, 8.1mm and 8.2mm for opening out the holes for the spindles. In fact the 8.1mm reamer fell into the inner hole on both carbs without removing any metal showing how much wear there really was, fortunately the 8.2mm reamer did in fact remove some metal so all was well. Reassembly was straight forward although getting the butterflies to sit correctly involved loosening the screws and flipping the spindles against the springs repeatedly.
Once the carburettors were reinstalled the engines started straight away and after adjusting the mixture controls settled down to an even tick over. Problem solved? It seems so, although I also had an issue with an oil-up spark plug. The only other thing is that the front carburettor with the new butterflies is now quite noisy on tick over, a kind of screeching noise which I assume is the air squeezing past the butterflies. The machined edges of the butterflies (13 deg) where very sharp compared to the originals, maybe I should have eased the metal slightly before reassembly.
I am very relieved to have got it all finished and pleasantly surprised at how much improved the starting is, I have never undertaken anything so drastic on carburettors before. Maybe wear on the carbs is a primary cause of old Fulvias reluctance to get going?
Happy Fulvia-ing to all!
John
