I have an old 302 from a 71 stang and I wanna put 351C heads on it I heard from a friend that you need machine work to do it any ideas?

 

Try here http://www.mustangforums.com/forumid_18/tt.htm

 

the guys at MF will most likely be able to tell you...

 

do a search at mustangforums i remember a while back a guy had a article on it, i think one of the water holes was different from the windsor to the cleveland.

 

I think you need a boss block to get the cleveland heads to work. Stick with 68-73 351 windsor heads. You will find that it all fits much better.

 

I think you'll need to machine new water passages to line up with "windsor" block,drill your head gasket too. If I remember, It calls for special intake and gaskets too. There used to a place called ? something River ? that handled that stuff.
I have thought about doing the same thing but depending what year 351c head your useing you may end up with a dog on the low end. That set up wont start working correctly til around 4000 rpm's due to the large valves and huge chambers and ports.
The aluminum after market heads for your 302 are awesome and you won't have compatability issues either.
Mustang and Ford just ran a feature on this not more than 5 or 6 months ago.
Good luck