Hi
I have a 1978 f250 with a 351m/400 and I would like to know if it is a small block or a big block and if it's a 351m or a 400.

 

The designation is a 335 series engine.
Other wise known as a Small block with a Big block transmission bolt pattern.

Unless to have the engine Buck tag,You will need to figure out the stroke to know for sure.

Piece of dowel inserted into the sparkplug hole measuring twice.
TDC & BDC.


Dennis

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[updated:LAST EDITED ON 01-14-03 AT 09:00 PM (EST)]go to bubbaf250.com they will show you how to locate and understand the I.D codes. take starter down you'll find a code D7TE this means 77 truck engine to find out if its a 351m or 400 take the oil pan down its the only way . 351m cast # is 1k or 1KA . 400 cast # is 5M or 5MA for a car and 5MAB for the 400 truck. these are stamped in the 1st counterbalance of the crank.good luck let me know how u do.

 

 

i have heard that the 400 has a thicker balancer than 351. the 400 is like an inch and a quarter wide and 351 is 3/4 of an inch.

 

The emmissions tag on the driver's side valve cover, just below the oil filler cap, tells you the displacement. It's on the top line of the tag.

 

This thread is almost three years old. The question was dealt with LONG ago in a galaxy far far away...