Someone answered and said not to use 350 heads on a 305 but when buying a set of heads through summit racing the heads are listed as follows 262-400 or all small block 1965-86 could someone explain?

.. The blanket statement don't use 350 heads on a 305 isn't correct. Many of the heads that came on 350 engines had large combustion chambers and fairly large valves, but some will work great. If you put a set of heads with large chambers on an engine that was set up (piston compression height) for small chamber heads you'd get very low compression, which would cause the engine to run poorly and have less horsepower. If you put big valves on a small engine such as the 305, they won't clear the small bores. The head castings from a 350 would physically fit a 305 block, but in some cases the engine wouldn't run very good. Aftermarket heads are sold with varying sizes of chamber volume and shape, different port volumes, and different valve sizes. A person looking for improved heads for their 305 engine should consult with one of the technicians at Summit racing or other high performance parts outlet about their application. Tell the tech what you will be using the 305 for...