Would there be any disadvantage in building up a 400M to basically be a killer stroked 351C? All the parts interchange right?
What about transmissions?
And more importantly what kind of power can a stock bottom end on a 400M handle?
There seem to be two main problems with the 400M. Fist, the stock timing is retarded so an aftermarket timing set is mandatory. Second, the heads are junk. They have very low compression, bad flow, and the only good use they have are for boat anchors. With a set of Aussie or 4V heads, you'd have a high compression, excellent flowing performance engine at a great price.
Again, this topic...my concern with it is what is the Compression Ratio going to be with the closed chamber heads, and more importantly, will the damned thing run on pump gas? If anyone could answer me those two questions, and is good news to me; I would definately take out my 351 C and put the goodies on the 400, and put Forged pistons on it. So...anyone wanna answer it or can anyone answer it??
I got these numbers from how to rebuild your Ford V8, page 38 335 series head interchange. swapping 70-71 351C 4V heads (62.8 cc) onto a 71 400 compression will be 10.4 and 72-80 will be 9.6
I dont know if anything else needs done, this is just swapping heads onto a 400. Sounds streetable to me.
swap on the closed chamber 4v heads -- must use adapter plates [ used to be available from weiand) and a tall distributor - (mallory used to offer one) -- to use flattop 351 c pistons - the rods need to have the small end bushed and the pins floated or custom pistons ---no one makes a an intake to match the large port heads on a 400 --- we had a couple of these in years past and it was a pretty good combo - if you have the room for it - 400's are wide
Has anyone here ever done this? ... And what fuel is required?
The only reason the compression ratio is as low as 10.anything:1 is that the (quench area/piston in the hole) is huge on this set-up ... This means you won't get the same "quench affect" that we are accoustom to on the 351C and I'm guessing that even at 9.6 to 10.4:1 compression your going to have to run race fuel in order to avoid detonation. Then if you cut the deck to get proper quench your going to be well over 12.5:1 compression ratio and most likely sitting with the exact same problem ... this is assuming use of flat top pistons.
You have to remember ... you are trying to squish an extra half inch of stroke into the same combustion chamber
My two cents ... Plan on running "Race Fuel"
There is some chance you could get around this problem cutting the decks and using dished pistons ... and still retain some of the quench affect.
Las Vegas Nevada
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Another couple things to keep in mind with the 400 vs 351C swap is transmission bellhousing pattern and motor mounts. The C uses the later 289, and302/351W 6-bolt pattern, whereas the vast majority of 400s used the same pattern as the 429/460 (and maybe others) pattern. Some 400s in 1973 (I think) had the small block pattern but they're pretty rare, as I understand it. Engine mounting pads on the block are entirely different on the 400s, again with the exception of the handful of small trans mount 400 blocks, which I'm pretty sure had both the C mounting bosses, undrilled, as well the 400 mount. Another consideration is that 400s are gonna weigh somewhat more than a C.
Hope this helps.