IF IT IS A LANCIA ENGINE - WE TUNED HER. IF NOT ASK.
Even the high quality parts Lancia produced for their engines do wear after serious use. If for example you take a rocker out of any head you will see the wear of the contact surfaces cause the valve to open less wide than originally intended. This hinders the flow and as such the fill of the cylinder.
Now you can go three ways: order new - regrind - or weld on. Same for the camshafts.
Valves you throw in the bin after you ordered new or wider sizes. And Valve springs get weaker, but stronger ones are available.
On the other hand, rockers as found in Ardeas, V6es and Flavia's have a connecting axle sitting in a neat block. The axles wear and the openings in the block widen. If no new rockers are available one has to chrome the axles and hone the bores.
Similar steps have to be considered for almost all other parts in your engine. Describing them all would turn this site into a book of Bible dimensions and as we know, we do not read the bible that often anymore.
Let me therefor show you some heads to give you an impression of the work we do. And can do for you.
This 900cc Ardea head needed a different size of the combustion chamber as the new pistons reached higher at TDC. A lot of grinding also opened the ports and allowed the wider valves to be used. All together a remarkable raise of output was achieved: Instead of the former 30Hp we now have 30% extra at 40HP.
The combustion chambers of the Appia are of the shape and size of a half tennis ball so you can have a dome that reaches high up.. The new CR? 11.3:1 in an Appia. Needed new conrods and a newly designed crankshaft to cope with the extra forces. But if you want to race there is no other way.
Quite the opposite was done to this Flavia head. To raise the compression rate: the combustion chambers had to be made smaller as in the domes of the pistons wide cut-outs had to be made to allow the wider valves some freedom at TDC. The black putty shows the spots where the welding could be done. The output went up from the 1800's standard 92hp to a stunning 150+Hp. With the help of the new spaghetti exhaust and the bigger carbs.