hey i have a 81 fiat spider FI timing belt was loose tension pulley did not seem to move spring is intact pulley rotates how does one adjust tension pulley ? have new belt but still loose any help will be thankfull

Hi, and welcome to FF

this section is normally for "bodywork" issues,

ask in the spider section.. but my suspicion is the cam-belt idler bearing is mounted on a thick "washer" with an off-set 8mm hole,
this is then placed onto a stub/ bolt, and you use a pair of pliers , etc to twist the mount around and tension the belt, then tighten the 13mm AF nut / head to final tension,
this MAY give you an idea ( different engine - similar tensioner)

https://www.fiatforum.com/cinquecento-seicento-guides/136702-cylinder-head-gasket-remove-refit.html

photo's of arrangements is 2/3 rds of way down page ,

Charlie