351m...
#4
they were just strange engines and came up in very dismal years as far as performance. it is cross between a small block and a big block. they just never caught on. you could of had a 351C or a 351W at the same time as it so.
#5
the 351m had a very low compression ratio it was around 8-1 which is terrible for any type of performance motor, unless of course you were boosting it which is a whole nother story. problem is nobody makes a good piston for it to bring that compression up, other than customs types which is quite expensive, as far as the cylinder heads go they had decent size valves stock but the exhaust port doesent flow well at all. and as far as intakes go there is not much out there for it, yes some guys have adapted cleveland intakes onto the m but it requires special intake to cylinder head spacers. and not to mention this motor is HEAVY! pound for pound your better off with a windsor or cleveland. is it possible to make these motors run like hell yes! it is but how much money are you willing to spend doing it? and dont confuse the cleveland with the m or 400 there are radically different, the cleveland was born and bred to eat bowties alive,
#7
theres nothing wrong with a 351m/400 but they have big block bell housing mount pattern and with the open chamber heads they are detonation prone without adding some 4V heads. but basically leave the stump puller 351m/400s for the 4x4 guys