Im confused, head help
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Postmaster
Joined: Mar 2002
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From: Coal Region
Im confused, head help
dont own and but im curious to know...what heads did the 351M/400s come with? i read conflicting info on this...some say there were both 2v and 4v heads like the clevos...some say they had just the 2v clevo heads...im just so confused...also read there were 8 different 400 heads? 
i just dont know...
i just dont know...
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Joined: Nov 2004
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No stock 351m/400 4V heads were made.The Early or as I call them,"Straight 400" in 1973 because they shared the same small block bolt pattern of the 351C but for one year only.The early 400 were produced from 71-74 only and came with 2 different heads,casting #'s D1AE-A and D3AE-G2B. The later "junk" 351M/400 from 75-80 came with 2 heads variations,D5AE-AA AND D5AZ.I call them junk because they had severe problems with oil consumption and extream fuel consumption for relativly low performance value.They were not one of Fords better ideas.If you are thinking about one go with the older 400 from 71-74.The later ones are plauged with low oil presure and in turn rod knocking.
Posting Guru
Joined: Mar 2003
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From: spartanburg, SC
351M/400 head are pretty much the same as 2bl Cleveland heads except for the AIR ports in later ones. The camber size seamed to change a little every year.
http://home.earthlink.net/~bubbaf250/index.html
You sure do know your part numbers fredy. (think you could put some pics of your 66 F750 in your gallery?)
"I call them junk because they had severe problems with oil consumption and extream fuel consumption for relativly low performance value."
"Severe problems with oil consumption" i don't see many threads about that problem. And if you do it usually caused by valve seals or worn rings.
"Extreme fuel consumption for relatively low performance value" that is not the heads fault, the stock heads flow better than some aftermarket 302 heads. Its the weak stock cam. i know a of more than a few broncos that get 13-14 MPG with built 400s.
The difference between the early and late heads that cause all these "problems" is A.I.R. Ports in the exhaust.
"The later ones are plauged with low oil presure and in turn rod knocking"
low oil pressure yes, lower than other engines, but how low is too low?
only 13 theads out of 4000 in this forum have "knock" in the title and they all aren't about rod knock. still not very common.
http://home.earthlink.net/~bubbaf250/index.html
You sure do know your part numbers fredy. (think you could put some pics of your 66 F750 in your gallery?)
"I call them junk because they had severe problems with oil consumption and extream fuel consumption for relativly low performance value."
"Severe problems with oil consumption" i don't see many threads about that problem. And if you do it usually caused by valve seals or worn rings.
"Extreme fuel consumption for relatively low performance value" that is not the heads fault, the stock heads flow better than some aftermarket 302 heads. Its the weak stock cam. i know a of more than a few broncos that get 13-14 MPG with built 400s.
The difference between the early and late heads that cause all these "problems" is A.I.R. Ports in the exhaust.
"The later ones are plauged with low oil presure and in turn rod knocking"
low oil pressure yes, lower than other engines, but how low is too low?
only 13 theads out of 4000 in this forum have "knock" in the title and they all aren't about rod knock. still not very common.
Last edited by F150daniel; Dec 8, 2004 at 10:34 AM.
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Modified junk
I worked at a large junkyard in Beaver County Pa by the name of Dons that had 60+ Acres of cars and trucks not to mention all the Ford vehicles I have owned over the years.I can't remember more than 3 or 4 351 M/400 that did not smoke,knock or suffer from from a combination of the 3 aforementioned problems.My brother worked at an even larger junkyard of nearly 100 acres in Ohio called Feezles www.feezleautowrecking.com and I can tell you from his experience that a Good running 351m/400 with good oil pressure and respectable gas mileage were few and far between and My Experience buying and reselling vehicles from Ebay that those engines are by far the worst Ford ever produced. Ask anybody thats owned more than one and if they are honest they will echo everything I've said and will also say that I've seen quite a few complaints about those engines here on this site.The reason I know my part numbers so well like you said should tell you something,you don't that much info unless you've had some experience with them.By the way I've got 3 junk ones laying behind my barn if anybody need some parts 2 from a 79 f250 a 1 from a 77 LTd station wagon.
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Joined: Aug 2000
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From: PacNW
Not to rain on anyone's parade here but there's a reason they're called "junkyards" & "auto wreckers". By the time most vehicles reach the point they're ready to be junked their best days a generally behind them.
I'm not trying to say that the 351M/400 were the best engines FoMoCo produced but considering the fact that they were a stop gap engine and beaten severely by the smog ***** I hesitate to condemn them as the worst engine Ford ever made. They had their share of quirks & problems just like any engine made but with some modifications and the right parts they can be very strong & reliable engines.
I'm not trying to say that the 351M/400 were the best engines FoMoCo produced but considering the fact that they were a stop gap engine and beaten severely by the smog ***** I hesitate to condemn them as the worst engine Ford ever made. They had their share of quirks & problems just like any engine made but with some modifications and the right parts they can be very strong & reliable engines.
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Joined: Nov 2004
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From: Rock Hill, South Carolina
had one that started knocking at 85000. drove it another 7k waiting for it to blow, it never did. Finally got tired of noise and swapped it out. Put 145k hard miles on another one (78 f250 snow plow). Never could kill it. Good oil pressure, no smoke or noise. no power either.
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I realize that they are a fairly dependable engine as far as running goes,what I said was that they were known for certain things,I never had one kill over on me completely,in fact I have had them go well past the 100,000 mile mark but they had more than there share of problems but they were not usually instantly fatal problems and that they were not considered one of Fords better engines,Now having said that I will also say that I would rather run a 351 modified 400 than anything Gm or Chrysler put out simply because I am a loyal Ford man to the end although I must admit the Mopar 318 ranks right up there with the 300 6 cyl when it comes to engine life,you just can't kill them.It all boils down to past experiences with these engines and we each have different experiences,some may have had good luck with them and some not but they just don't stack up to the 300 6 cyl or a 302 or 460. If you think about it How long has the 460,the 302 or 351w,300 6cyl been produced by Ford? They were all introduced in the 1960's and were still in production 30 some years later and some still today but look at the 351 modified/400.The 400 was introduced in 1971 I believe and the 351 modified in 74 but disappeared in the early to mid 1980s. Now if it had been one of there better engines I don't think Ford would have walked away from them.
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