Re: Ford truck questions(1979 F100-1979F150)

Posted by John McPherson on June 22, 2005 at 10:43:36 from (216.251.171.228):

In Reply to: Ford truck questions(1979 F100-1979F150) posted by Jak on June 22, 2005 at 07:10:03:

The 351 you have is actually called the 351 M (Modified). The 351 Cleveland was used in the cars until 1974 production began, when it was dropped from the car lines.

Ford was never really clear why they made two different 351's, but from what I have read is that one was intended for "truck only" usage (351W)initially. However Ford, being Ford, that did not last long.

The 351 C, M and 400M are technically a "big block" in old race rules packages. The coolant flow is the real "significant" difference between the two. The upper radiator hose attaches on the manifold in the windsor series, and the Cleveland/Modified series has the upper radiator hose attaching on a casting that sits behind the water pump. There is no coolant crossover at the front of the heads of the Cleveland/modifieds as that flow is throught that casting.

The size of the ports are different too- they are larger on the Cleveland/Modifieds when compared to a 351W.

Without some rework, there is very little other than routine maintainence items between the two engines that will interchange.
With rework, (plugging coolant passages and drilling), the heads and the intake manifold can be swapped as a set between the two engine families.

The brake booster will be a doable swap, but you will want to swap the master cylinder too.

The fan clutch is not required as your factory fan is supposed to flex (change pitch) based on cooling needs of the engine based on speed of the engine. For practical purposes, the fan clutch is only going to add maybe 1 to 3 miles per tank of gas. Yes it adds up, but is it worth the bother to you? That old fan clutch may need replacement soon anyway.

On other notes, the transmission and bellhousing are a different bolt pattern from the Windsor family. The frame and suspension is also different between the F100 and F150. Some parts can interchange, but not too many- Measure them first and check Ford part numbers carefully for that last letter on the basic part number.

Follow Ups:

• Re: Re: Ford truck questions(1979 F100-1979F150) Jak 13:55:07 06/22/05 (2)
  • Re: Re: Re: Ford truck questions(1979 F100-1979F15 Calvin C 12:15:11 07/07/05 (0)
  • Re: Re: Re: Ford truck questions(1979 F100-1979F15 John McPherson 07:18:37 06/24/05 (0)

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