my thoughts, the stock heads are the same as the 351c and they flow ok, for a crap design. the short side in a 90 angle, the valve sizes are good. the exhaust flows a little better than d2te heads. The timing is retarded on the 351m/400 from what i gather. Not to mention many had ac, smog pumps, and emissions oriented everything.

Back to the heads, they are open chamber design and it seems they can not tolerate any compression. You would need something like the aussie 2v heads to run a 9.5 cr. or a ****ty high duration camshaft, to bleed everything off.

As for aftermarket, thats a different game. The FE puts a hurtin on the 400 unless you buy custom intake adaptors.



FTE A.D.D member