[Rick Parker]

Back in the late 70's when the 400 and 351M were relatively new in production they had a real problem with short valve guide life; after a very few thousand miles on new cars the valves began to clatter, it got to be a real problem that no one had a real answer for. After a lot of repairs and various excuses it was deemed that a revised method of chroming the stems had caused them to be a little rough from the beginning and they were like a Rat Tailed file in the valve guides. Those in the know began doing the repair using non OEM valves and all was well. You could feel the roughness on the valve stem with your thumbnail. 400 cu in, 2bbl carb and a retarded cam, with early electronic ignition was a real recipe for disaster.
Check this:



SPECIFICATIONS
ENGINE CODE ENGINE DETAILS
1. F

Optional:

2. H (351 Windsor)

3. Q

4. S 1. 302 CID 2V V-8
Bore and Stroke: 4.00 x 3.00 in.
Compression Ratio: 8.4:1
Brake Horsepower: 134 @ 3400 rpm
Torque: 248 lb.-ft. @ 1600 rpm
Carburetor: Motorcraft 2150 2V

Optional:

2. 351 CID 2V V-8 (Windsor)
Bore and Stroke: 4.00 x 3.50 in.
Compression Ratio: 8.3:1
Horsepower: 145 @ 3400 rpm
Torque: 277 lb.-ft. @ 1600 rpm
Carburetor: Motorcraft 2150 2V

3. 351 CID 2V V-8
Bore and Stroke: 4.00 x 3.50 in.
Compression Ratio: 8.0:1
Horsepower: 152 @ 3600 rpm
Torque: 278 lb.-ft. @ 1800 rpm
Carburetor: Motorcraft 2150 2V

4. 400 CID 2V V-8
Bore and Stroke: 4.00 x 4.00 in.
Compression Ratio: 8.0:1
Horsepower: 166 @ 3800 rpm
Torque: 319 lb.-ft. @ 1800 rpm
Carburetor: Motorcraft 2150 2V