Cant get engine to run proper,need to set timing, help runs rough,sometimes first low rpm
Pretty poor description you wrote there and, of course you told us nothing about the car, when this started, what you’ve done so far, if you are doing the work yourself… nothing, really.
Either explain yourself better or find a gray haired guy really familiar with obsolete vintage Italian autos.
I used to work on these things quite a bit; not out of choice. You have provided little info as to mileage, whether or not it was running halfway decent before, and so on.
Setting the timing is pretty cut and dried. Unless the timing is a mile off that is unlikely to be causing the rough running.
Considering the age/miles? my suggestion is to always run a compression test. There is no sense doing anything or spending any money if the engine is losing a cylinder; or all of them.
Are you using gasoline that contains ethanol in your old Fiat?
First start with the cam timing on this engine. With the engine at 0 degrees TDC on #1, check the markings on the cam gears to make sure they are right. If one or both of the cams are off, setting the ignition timing will never work.
The pull the distributor cap and make sure the rotor is pointed at or close to the #1 spark plug tower. Turn the crank to the initial timing setting specified, note you must turn the crankshaft almost two full turns to the mark, do not turn the engine backwards.
Then align the distributor so that either the points are just starting to open or the vane is pointed directly at the split in the ignitor if you have an electronic ignition. Start her up and make the final timing adjustment with a timing light (vacuum advance disconnected). Lube the mechanical weights if needed.
I owned an earlier version of the 128 Spyder for a couple of weeks. Too complicated to explain. But it ran pretty well for me for the time I owned it. This symptom sounds like a carburetor problem to me. I had a similar problem on my Ford truck of a similar era, and had to rebuild the carburetor to get it running well again. The upside of taking the time to rebuild the carb, the engine is running pretty much like new.