Originally Posted by 96s10v8
I dont know much about 350 sbc's but the guy i got it from was running unleaded gas instead of premium gas. will that hurt anything? should i switch to premium? is it ok to just start adding premium if i still have regular gas in the tank?
Premium is also unleaded. Depending on where you live there hasn't been a leaded pump fuel for nearly 30 years.
On a ledge of the block just in front of the passenger side cylinder head therre will or should be a stamped code which will tell you when and where the engine was made and there may be the vehicle VIN number there which will tell what it's from and the year. If nothing else under the rocker covers aout in the middle of the head is a casting number, it can shead some light on the period (year) that head was used. All of this can lead you to know whether the heads have hardened seats for unleaded fuel.
Check this for a data source: >>> Small Block Chevy Engine Block casting and code identification
There are several others on the web if this doesn't have what you need, or tell us.