i just wondering if 400 block same bored as 351m?

can i change 400 to 351m? look for rebuilt 351m for my 78 ford ranger XLT little better gas mpg than 400?

 

They both have a 4.00" bore, mpg won't be any better though.

 

Same bore. If your looking for better mpg don't bother with the 335 series engines., especially if you are going through all the trouble of pulling the engine anyway. Swap in a 300 with factory 1 barrel carb and you will notice a significant gain in mileage

 

Here is some good info for you...

351 M Engine dimensions
351M/400
351C
Nominal main bearing size
3.000 in (76.2 mm)
2.750 in (69.8 mm)
Rod length
6.58 in (167.1 mm)
5.78 in (146.8 mm)
Deck height
10.297 in (261.5 mm)
9.206 in (233.8 mm)
When the 351 Cleveland was discontinued after the 1974 model year, Ford needed another engine in that size range, since production of the 351 Windsor was not sufficient and the 390 FE was also being retired. To replace the 390, Ford took the 400 engine's tall-deck block and de-stroked it with the shorter-throw crankshaft from the 351 Windsor, and taller pistons, to produce a 351 cubic inch (5.8 L) engine whose components were largely compatible with the 400. This engine was called the 351M and as a back-formation the taller-deck block became known as the M-block.

The M designation is commonly referred to “Modified”, and is derived from the use of both "Cleveland" (block, heads) and "Windsor" (crankshaft) components in the same engine, a modification for the parts' intended application, so to speak. All 351M/400 engines were cast at the Michigan Casting Center until mid year 1978 when manufacture was transferred to the Cleveland Foundry. The block castings were modified to prevent cracks in the lifter area and x's were cast next to each lifter bore. Another origin of the M designation may have come from where the engine blocks were cast. It follows the naming convention set forth by the 351C (Cleveland) cast at the Cleveland Foundry and 351W (Windsor) where the majority of the blocks were cast at the Windsor Casting Plant. From the introduction in the model year 1975, the 351M engine blocks (which are the same as the 400 engine block) were all produced at the Michigan Casting Center (MCC) in Flat Rock, MI or at the Cleveland Foundry (CF) also known as the Cleveland Casting Plant (CCP). To help distinguish it from the other two different 351s, the logical choice was to use the Michigan Casting Center, hence the “M” designation for 351 Michigan.

The 351 Cleveland had a well-known, good reputation in the public. For a few years after its introduction, Ford marketing called the engine the "351 Cleveland". This led to confusion as to which 351 version was actually in the vehicle.

Later, car enthusiasts incorrectly referred to this engine as a "351 Midland" presumably a reference to Midland, Michigan, a city just northwest of Saginaw or reference to an iron foundry in Midland, Texas. But the Ford Motor Company never owned a “Midland” factory.

 

if both is same bore why it differnt 400 and 351?

 

B&S: 351M: 4.00" x 3.50" / 400: 4.00" x 4.00"

351M: 1975/79 Ford/Merc Passenger Cars // 1977/79 F100/350 / 1978/82 Bronco / 1980/82 F150/350.

400: 1971/79 Ford/Merc Passenger Cars / 1978/79 Lincoln/Continental Mark V // 1977/79 F100/350 / 1978/82 Bronco / 1980/82 F150/350.

 

is that reason differnt only crankscase but rest is same bore correct?

 

351M/400: Same engine block (F100/350 & Bronco only), 351M has a different stroke.

See post 6 for edited in 351M/400 applications.

FoMoCo referred to the 351M = Modified from day one. There is no such thing as a 351 Michigan or 351 Midland.

There is no such thing as a 400M either.

 

I just curious does MPG same or big different for 351 and 400 ?

 

These trucks have the aerodynamics of a brick. Gas was relatively cheap back then, most peeps didn't give a hoot about MPG

Expect no more than 8-12 city, doesn't matter if you have a 240 or a 460. You might get as much as 18 highway, if you drive like Uncle Fudd, no more than the double nickel.

There's next to nothing you can do to improve MPG, whether you spend a grand or 10 grand. All you'll be doing is throwing your money away that'll buy a heck of a lotta gasoline.

People buy full sized pickups, then expect good MPG. IMO, that's ridiculous, cuz it ain't gonna happen. I've bought 8 new Ford pickups from 1965 thru 2011.

The only one that got decent hwy MPG was the '65 with Warner T-85N O/D. But I didn't give a damn, because I never expected to get decent MPG from a truck.

You want decent MPG from a daily driver and you have a limited budget? Buy a 10-15 year old Accord, Altima or Camry I-4. City will be 18-24, hwy could be as much as 36.

 

i agree w y but what about HHO? have anyone try? HHO Dry Cell Kit Hydrogen Generator Fuel Economy MPG Browns Gas Electrolyzer | eBay

 

Never heard of it, wouldn't buy or install it, because who knows if it will improve anything? The only thing it will do...guaranteed, is drain your wallet when you buy it.

Since day one, there's been all sorts of gadgets available to improve MPG. None ever worked worth a damn.

One that was advertized in Motor Trend and etc in the 1950's was nothing more than a metal cannister w/a glass bowl with a ceramic do-dad inside. Mounted in front of carb.

I forget what the terd was called (Mileage something or other) but it was as useless as teats on a mule.

 

HHO , should be ho,ho,ho ,you though away your money, will not work.

 

A few hints to remember...
351/400 8 to 12 mpg depending around town and hi way
460 8 miles to gallon, hauling or bed empty

 

if you make some modern upgrades can gain a few mpg for the low low fee$$$$.