350-400HP 351M

Discussion in 'General Ranchero Help' started by Matt Winters, May 17, 2021.

  1. Matt Winters

    Matt Winters In Second Gear

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    83
    Yea that's right, pretty crusty under there. My grandfather did put a 4.56 rear end in it, which I plan to remove. Perhaps he was slowly killing it by over revving it on accident? He has always said if he mashed the gas down, you could shift all three gears before you cleared the intersection!
     
  2. 6delta

    6delta In Fourth Gear

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    258
    Location:
    Citrus Heights, CA
    If the engine sat for over a decade I am not surprised you had a problem, I would agree that the lifters may be the culprit. I wouldn't be shocked if you had some other problems also. Who knows where the oil may have decided to sit and turn into a gooey plug given the time from 1991 to now.

    You may want to check out the 351c.NET forum and the TMeyer site regarding the 351M. There are some builders there that work with the 351M and the 400 and have pretty good luck. I haven't been on that site in a while but I did not remember the problem with the 351M block being the bottom end. I thought there were some blocks that had a problem with the upper lifter valley walls developing cracks (and it was in a particular build date/location of block also). There were guys using them in mud racing rigs and other competitions that needed engines that could survive modest high rpms. My only experience with the 351M and the 400 motors of that era is limited though.

    Good luck.
     
  3. Matt Winters

    Matt Winters In Second Gear

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    Thanks for the advice. I've researched this a little . . .I don't doubt the folk on this site and what they have to say. However, I seem to not find any substantiation of this claim elsewhere. I know they aren't 7500 rpm engines or anything, but I somewhat doubt this is as precedented an issue as it's been made to be here.
     
  4. Hillbilly

    Hillbilly In Maximum Overdrive

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    Winchester, TN.
    Wouldn't want it public about how many loyal Ford customers went over to GM and Chrysler thanks to those wonderful "M" engines. Around here those "M"s were a blessing for Ford's competition. Like new barely out of warranty car dead in the water, local mechanics around my dirtwater town likely changed out over 100 excuses for an engine. Thanks Ford, you kept our bills paid nicely. A 4.56 rear gear answered all my questions. Crying shame scrap metal didn't bring much back when those were new.
     
  5. Matt Winters

    Matt Winters In Second Gear

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    It shall live again, I say!!!!
    On a serious note, I was told and believed it was a Windsor. That's what my grandfather thought. It is entirely possible he misremembered, or it is possible the previous owner lied or was mislead himself. After all, if these are really lemons, it would make sense.
     
  6. Hillbilly

    Hillbilly In Maximum Overdrive

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    Location:
    Winchester, TN.
    I can see possibly confusing an "M" with a 351 Cleveland especially if you didn't know the visual cues, but a Windsor ? Did Grandpa previously have many Fords or was this his first venture into the crazy Ford world ?
     
  7. Matt Winters

    Matt Winters In Second Gear

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    He's only ever bought Ford's. He bought it back in 89. Story goes he had a fight with the wife, and went out and bought to piss her off. Like I said, he bought it in 89 and parked it in 91; it's very possible he just forgot, given he hadn't had anything to do with it for thirty years.
     
  8. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    Location:
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    Well, to clear the confusion, Windsor's have the thermostat housing on the end of the intake, whereas the 351C/M/400 engines have it on the top passenger front of the block, no intake water passage. Also, since you were under a valve cover, if all the valves are oriented straight up, it's a Windsor. C/M engines have canted valves.
     
  9. Matt Winters

    Matt Winters In Second Gear

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    The thermostat is where my suspicions started. The "M" on the intake was pretty convincing, but the staggered valves sealed the deal: it is, in fact, a modified.
     
  10. Hillbilly

    Hillbilly In Maximum Overdrive

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    Another clue is Clevelands have a relatively flat area around the thermostat neck where "M" engines have raised cast iron lumps close to the thermostat neck. Never figured out the purpose of that raised area other than possibly it was used as a support during machining. Cleveland also has the number "2" or "4" cast into the upper corners of the heads while "M" heads are blank in the upper corners. Cleveland sports the small block bell housing pattern while the "M" uses the 429/460 bell housing pattern. Some of the early late 1970 build 400's even had the small block bell housing pattern but they are rare today as they didn't live very long.
     
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  11. burninbush

    burninbush In Maximum Overdrive

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    You can buy replacement pushrods in the auto parts stores. Be careful when mounting the rocker pedestals, watching for rubbing against the head metal.
     
  12. rocco611

    rocco611 In First Gear

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    Location:
    Madera
    the horsepower your looking for will be in the cylinder heads and increasing the compression . a big cam in a stock motor will be a disappointment. there are early cleavland heads and aussie heads out there that are not terribly expensive, the aluminum heads on the market have diminished the value of the good iron heads out there. look around, this is the best place to spend your money. clean the block and have it magnufluxed, if it doesnt have any cracks it will probably be fine, be sure to do the oil restrictor mod to the block . I built a 351C , shoe horned it into a 70 maverick , it ran a 9.90 1/4 mile with port plated 4v closed chamber cobra jet heads , 11-1 pistons , a holley 850 dp. and custom solid cam from Chet Herbert, Chet has been gone a while now , I do miss him. the other thing is buying an off the shelf cam is not the best idea. when you figure out what you can afford, what parts your going to use, call a reputable cam grinder and give them the details they ask for, they will create a custom grind that will likely be better than anything you could pick out of a catalog.
     
    Last edited: Jun 4, 2021

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