i have a older sea ray boat that has a 351 windsor i am told. how do i tell if it is a 351w, 351c or a 351m ? it is the origional moter and has a 2 berral carb and the spark plugs are set at an angle. does any one know ? :banghead:

see if you can get the serial number off the actual block. Should be on one of the sides just below the heads or above the oil pan. Then find a serial number listing on yahoo and see if you can match the numbers.

it's probley a 351 mod 400. i had this in my 4 wheel drive truck.

Old post but,

If it has a dry intake (upper hose goes into the timing cover) it is a 351C or M. If it has a coolant neck into the lower intake, it is a 351W.

The C and M look a lot a like, you can tell by timing cover, 351c is flat where the coolant goes into, and the (351/400)M is raised about an inch or so. There are pretty interchangeable (cam, heads, NOT intakes), because they're from the same engine family. Intakes won't interchange because of deck height, although spacers have been made to adapt 351c intake onto a modified.

351/400M are essentially the same blocks. The later truck blocks are a lot better with the thrust bearing upgrade w/ manual trans (D7TE?). Only way to tell if it's a 351 or 400 is by removing the oil and looking at the casting # on the crankshaft.

351c has sbf motor mounts and bell, where most modifies have bbf mounts and bell. I believe some 400s were small block bells though. The Ms are big bastards.. Performance wise, you can get power out of it, but at a high cost. Personally, I'd rather have a windsor block..

Pete