hi ive a friend who has a 1971 fiat 500.

cut a long story short the treads are gone in the head of the 500,exhaust mounting bolts in head are torn out the threads in the head, they had been helly coiled already

he has a 126 engine in a shed,id say it dates from 1988??

would this head go on the 500 bottom end?? same stud pattern?? combustion chamber the same??

any info would be a god send before i start removing heads etc.

thanks jason

The 126 head WILL fit onto a 500 engine, but you will probably find your performance reduced. The 126 is of either 595 or 652cc, and the head will be made to suit the appropriate bore.
You really have 3 choices--(1)--refurbish the 126 engine and then fit that into your 500 (which will give a performance boost). Don't forget though, the gear-box bell-housing will need to be changed to that from a 126 (different starter mounting position)
(2)--Remove the 500 head and get it refurbished by a specialist--I always fit the MEMFAST "self-tapping steel inserts" in where the exhaust bolts fit (and use studs, with 2 PLAIN nuts to secure the manifold in place).
(3)--heave the 500 out and stripped, get the crank-case machined out to take the 126 barrels and rebuild the engine as a 500/126 hybrid. This is basically what we did at Radbourne Racing when we fitted the 'Nardi' 652cc kits.
Option 2 would probably be the sensible option, but 1 & 3 would be the most fun, and give a performance boost.