390 vs. 400
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Junior User
Joined: Apr 2005
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390 vs. 400
Now that I have a 79 f150 as well as the 70, I have just been comparing similar features between the two. Now I am just curious about the 400. How did the 400 compare to the 390 in power and milage when they are both stock?
Lead Driver
Joined: Apr 2001
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From: Texas
Just to get a balanced opinion, you should also ask in the 400 appropriate engine Forum. From what I've read, you can do a lot with either motor. Do you plan to run a stock motor or make some changes? What is the intended use and what is your budget?
Senior User
Joined: Nov 2002
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you seem to be the only one. i never hear anything good about the stock heads
they are 2V 351C heads.........I always wanted to build a set with 4V ex valves and screw in studs.....it's been about 20yrs now but I built a 351C 2V motor for a 68 stang I had....It was basicaly stock except for a 270/290 cam and a 4bbl....that motor haul'd A$$......I almost put a 400 in my 71 F100.......I really believe all that motor needs to perform is a hotter cam and more compression......
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Postmaster
Joined: Jul 2003
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From: iowa
my thoughts, the stock heads are the same as the 351c and they flow ok, for a crap design. the short side in a 90 angle, the valve sizes are good. the exhaust flows a little better than d2te heads. The timing is retarded on the 351m/400 from what i gather. Not to mention many had ac, smog pumps, and emissions oriented everything.
Back to the heads, they are open chamber design and it seems they can not tolerate any compression. You would need something like the aussie 2v heads to run a 9.5 cr. or a ****ty high duration camshaft, to bleed everything off.
As for aftermarket, thats a different game. The FE puts a hurtin on the 400 unless you buy custom intake adaptors.
FTE A.D.D member
Back to the heads, they are open chamber design and it seems they can not tolerate any compression. You would need something like the aussie 2v heads to run a 9.5 cr. or a ****ty high duration camshaft, to bleed everything off.
As for aftermarket, thats a different game. The FE puts a hurtin on the 400 unless you buy custom intake adaptors.
FTE A.D.D member
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Logistics Pro
Joined: Apr 2005
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I'll easily admit I have an FE bias, but I had a '79 F-250 with the 400 and a 4spd, (first a NP then a T-18), for many years and that was one strong truck. It sure had a lot of smog junk on it, but it didn't seem to hurt it any. A buddy of mine had a fresh 390 with a mild cam in a '73 F-250 and he couldn't catch me on the freeway. Sure had a lot more get up and go than the old 360 I have now.
Got 12mpg with it too and that was with a young man's lead foot. I miss that truck.
Got 12mpg with it too and that was with a young man's lead foot. I miss that truck.
New User
Joined: Oct 2005
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I have personally been pushing fords for over ten years and i prefer the 400 over the 390 it turns on quicker after some better pistons, cam,intake, and carb. I have one as my daily driver and i can chew up just about anything on the highway. And i am about even with a 390 out of the whole. They ar both stout motors.
Posting Guru
Joined: Oct 2005
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i just reworked a 400 for a friend of mine and all I did was put on a performer intake and a 780 vacuum secondary holley with that powermax 266 cam and some headers.. the trucks are nearly identical for weight and we run the same tires. that truck of hers pulls alot harder out of the hole than my 390 but cant keep up at the top end. with the exception of intake manifold selection, parts seem to be more readily available for the 400, and400's are dirt dog cheap compared to the FE.. like gashog said though, they are not nearly as stout as an FE... being kinda hard on things i prefer the FE.. LOL
Senior User
Joined: Nov 2002
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Back to the heads, they are open chamber design and it seems they can not tolerate any compression.
I've seen this posted before although I believe they handle 9.2-1 - 9.5-1 on pump gas without a problem..... 10 -12 degrees initial maybe 37 total ..... 89 octane.....they are hard to find but there are flat tops out there for the 400 that will put you in that cr range without going to aussie heads...
Postmaster
Joined: Jul 2003
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From: iowa
the 1972 open chamber 429/460 head is dissed all day long as well. Well, instead of talking static compression, the dynamic compression the open chamber can handle is less than about any other chamber design.
Senior User
Joined: Nov 2002
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Well, instead of talking static compression, the dynamic compression the open chamber can handle is less than about any other chamber design.