Bought a 85 GMC custom van. Owner said that it had a 350 in it but the options tag says 305. It has a huge 4bbl carb on it. Did the 305s come with a 4 bbl and where on the block can you look to see what it acutally is.

 

Look on the back of the block by the bellhousing,
The numbers will be cast in the block below the distrubuter,

then go here, to decode

www.mortec.com