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The 516s are boat anchors, If read in the mopar bible you dont want to put the 516s on a 400... Ive looked into the 400s alot in the past because my brother and i were both doing builds like yours, Use the 452s and a 268 cam Aluminum intake and holley 750 DP, quick advance springs, headers or good manifolds and she will run hard....



closed chamber heads...boat anchors...right!

I guess by your logic my boat anchor equip'd 383 would have been better off with the 906's it originally had on there which resulted in a fantastic CR ratio of 7.8:1. With those boat anchors I managed to pick up the CR to 9.2:1 with some minor decking...try doing that with an open chamber head...

To me I would not even waste time on an open chamber head...they are the true "boat anchors" in my book.

It is true the valve sizing and port design are not the best. that is why the 915 is more desirable, but the closed chambers make up for a lot of that...especially on 383/400's where piston choice is so poor.

Like anything they need some work to make do, bigger valves, porting, etc. but if your simply gonna do a straight out comparison by bolting on a set of 516's vs ANY open chamber head the closed chamber head will result in more compression = more power.

Wasn't 383HP running a set of 516's on him or his sons dart on a 400 that was running in the low 12's or something?

the 452's that i have are 80 cc's and have had some bowl work,if the 516's r better i'll use em,should i put the better exhaust valve n em first and have everthing checked?they are bone stock as they sit,and the milled 452's are ready to bolt on,thanks everyone for the responses