Do the 351M heads have larger valves?
 

So I've been told that the 351 heads will bolt onto a 305 and was wondering..do the 351 magnum heads have larger valves besides larger ports?

Re: Do the 351M heads have larger valves?
 

Magnum heads do have larger intake and exhaust valves from the 305 heads but will also lower the compression when installed on the 305. Also all Magnum heads are the same regardless of the engines displacement. You would be better off replacing the 305 with a larger 351 or 401M V6.

Re: Do the 351M heads have larger valves?
 

It's crossed my mind to do a swap, but I'm a guy who likes to hop up stock engines. Did a 292 I6 in my chevy...coulda gone the 350 rout like everyone else in this world has but liked the 292 so hopped it up and will embarrass 350's with it now. The 305 I don't want to make a rpm engine out of, but just make it better. Heard of some perrty cool mods that people have done. Thanks for the response!