UNLEADED

Can anyone tell me whether a 1983 1500 model needs to be converted to run on unleaded as I have read that they will run fine without conversion and addittive etc? The car won't be covering large distances, only used at weekends and not hammered on motorways etc

Mine does very well. Redex for some reason seems, maybe in my imagination, to make it run even better but unleaded is fine as, having an alloy head, there are hardened valve seats.
The best improvement was the Fiat Uno or Panda electronic distributor. So smooth.

Will be fine but change out the fuel hoses for modern ethanol rated ones

I always use that Shell Premium unleaded - expensive but higher octane - think its 99 ?
I add that stuff from Halfords (Wynns Lead Substitute with Fuel Stabiliser) Lead replacement additive.

As I understand it the cars were a wee bit ahead of there time ( as I find most Fiat are) and they were built to run on unleaded fuel. Personally I would only run standard fuel as a few people I know who’ve used premium fuels have had running issues going forward, I have never put any additives in ( don’t know about the injection cars in the USA )

Shell V Max and the rest have a higher octane rating, which our cars don't need, but more detergents. I think they may have less ethanol which sucks water into the system but the ethanol rating is on the pump.
When you look at the advertising of fuel over the years there has always been a way of making the motorist dig deeper into their pockets.
When tetra ethyl lead was introduced into fuel in the 1930's it was for the Schneider Trophy engines that had very high compression, it was designed to slow the flame front and reduce pre ignition.
"I kept no Diary" by Francis Rodwell Banks tells the story.
The water that ethanol traps in the fuel can corrode parts but can also, I think, act as water injection and cool the charge but I am not sure about that.
The lead protected valve seats but as our heads are aluminum and have stellite seats we don't need to protect them like they did.

There is a letter from Fiat somewhere in the Club archives that says something to the effect that the Exxy is fine to run on unleaded fuel for "normal driving" but that it would benefit from valve additives for "sustained high speed running"
I've always used Valve Master Plus 'cos most of my Exxy driving always seem to include 2 or 3 hours of motorway bashing at a time - and I'd rather be safe than sorry!