351 Modified W/tranny Q's

Killer50stang

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May 11, 2004
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I got a 351M with tranny out of a 78' ford f-150. What is the difference between the 351M and the 351 Windsor? What tranny would this be also? It has sat for a while and does not run, but the truck is solid and the engine looks clean. Any tips?
 
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Killer50stang said:
I got a 351M with tranny out of a 78' ford f-150. What is the difference between the 351M and the 351 Windsor? What tranny would this be also?

What is different? Quite simply.......everything. The 351M shares more with a Cleveland and 460 than anything else. Its actually like a 351C, but it has a taller deck and 3.00" crank mains(Clev had 2.75" mains).

The 351M also took a bigblock(385 series) trans, meaning you have a C6 if its an automatic. The 400 is actually more desirable, albeit only slightly. From what I've heard, the 351M and even moreso the 400 make decent truck engines.
 
I plan on pulling the motor to paint the bay. The motor has 124k on it. I plan on rebuilding it, as in gaskets and so on. Should I replace the pistons? or just the rings and seals? This isn't going to be a hot rod, like the stang.
 
Are you putting it in a truck? Or a mustang? It will do fine for a truck as long as you dont try to pull anything real big. Not a good choice at all for a Mustang, though. Its not a bad engine, its just that the 429/460 are vastly superior, even the 351w is WAAYY better for truck and car apps. Not alot of aftermarket options for the M motors.
 
My dad has a 400 in his 78 F250, runs like a dream. It has pulled a skidloader I used at my house, which was like 10k lbs, and the trailer that was like 5k lbs.. towed just fine 80mph up the highway.
 
i have a 400 in my 79 f 150. They are better motors than people think. from the factory they werent great but considering the times they were produced what do you expect. There was an article in hot rod i believe years back where they made 380hp and 486ft lbs for under 2k. Prices would probably be a little higher but that you could get good power for a decent price. Here is the article http://www.geocities.com/styleline58/400.html
 
check the crank to see if it is indeed a 351m and not a 400 (its the only way to make sure, for sure). if its not a 400 get a new 400 crank and pistons, mind as well upgrade them too but make sure the new ones are for the 400. the 351m is just a destroked 400. you can easily get this block to 400+hp and around 480ft lb for under 2grand. pm me if you want me details.
 
Well, first thing is that I don't care to make alot of power out of this motor, as it is staying in the f-150. I just want to know what I should replace since it's going to be pulled to spray the bay anyway. I've seen rebuild kits on ebay for around $300 with pistons. I'm not real familar with the 351M since I'm a 5.0 guy. Just looking for tips. Motor has 124k on it, but it's sat for a long time.
 
I didn't make the connection that it's out of a truck. That means it has a good chance of being a 400. As for rebuilding it, just look it over. Just because it's been sitting doesnt mean the engine is bad. Maybe pull a head and see what the bores look like. If there isn't a ridge, you could probably get away with re-ringing it.
 
65ShelbyClone said:
I didn't make the connection that it's out of a truck. That means it has a good chance of being a 400. As for rebuilding it, just look it over. Just because it's been sitting doesnt mean the engine is bad. Maybe pull a head and see what the bores look like. If there isn't a ridge, you could probably get away with re-ringing it.

How can I tell if it's a 400? Should I have the bottom end done by a shop? or attempt it myself? Never done pistons...