Heres the story: I have 2 broncos one is a 74' and one is a 73'.
The 74' Im building for off road and obtained a 70' 351W Im rebuilding for it.Its pretty much done and I bolted on Ford GT40 heads(the y303 heads).The 73' Im also rebuilding the original 302 and want to use the heads off the 70' Windsor to get a little better performance.My problem comes from some people Ive talked to that say bolting on the 351W heads will drop the compression a full point and that there are other issues with the rocker arms pushrods etc.I was told the 73' 302 heads are 63-64cc chambers and I know the 351W heads are 60cc chambers,so how does this decrease the comp. ratio instead of raising it.I know I need ARP's bolt kit to bolt the 351W heads on the 302's 7/16 holes but what other issues am I looking at?

 

swapping heads with small blocks goes both ways. they are all the same bolt pattern height etc, i put 289 heads on my windsor an cammed it just had to drill out the holes. the 60cc heads will raise your compression there is a place on this websight for figuring compression ratio. the 69 to 73 windsor heads also have slightly bigger ports on the intake side i think, and slightly bigger valves, it will make it run a lot better and breathe more at higher rpms, i have seen some tricked out stuff with these heads but to a lot of peoplr these r old school b/c after u spend the dough portin em u could just as easily go after market. but i would run the old iron any day of the week. i would be thinking about cam also because when u raise compression u want to run a longer duration to prevent detonation 215 no more than 224, inless u want to though u might not have any problems