71 f100 prerunner

[LENNY]

The trout is 4976 with a full tank of fuel, but still have a few things to add so I think it will be right around 5500 all said and done. And I could be wrong but I am pretty sure a 400m never came with over 300 ft pounds of torque from the factory, so even with a small cam, intake, 4 barrel carb and headers it will still be quit a bit under a stock ls3. And my 400m seems to start falling on its face before 5000rpms. I am looking at getting a lq9 junk yard motor, and throwing a cam and maybe set of cnc ported l92 heads, they are pretty cheap and make great power numbers. And with the fuel injection it would have to be a lot more efficent than a 4 barrel carb on fuel.

saw a artical on line they took a 400m rebuilt it with a RV cam and the stock 2v intake it made 265hp/400lb tq added a intake and 4 barrel and they ended up with 285hp and 415lb tq so I THINK im in this range with 518 gears but I hve to do somthing about the 3.5mpg,Pacific performance has built a few 400mutt motors and his numbers with a set of heads and roller cam are 490hp and over 500lbtq,DD what kind fuel MPG is the Trout doing and what gears are in it.

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[LENNY]

Our prerunner has a 400M and that thing runs like a raped ape. some good head work, cam and timing will allow the motor to open up and make really solid power. I would also say the same about our stock full but im not sure its actually a 400...

Bring what kind of numbers please HP/Tq how much does your prerunner wt,what gears and what does it get for MPG,Ok heres where im at I would like to stay with a ford motor cause its a old school ford and if I can get the MPG up on this 400mutt engine ill be good,now if I change the motor im going LS style and 4l80 now I have to make all new mounts this could get out of control reel quick,Thanks for the help guys and DD sorry to have taken over your tread.

[atomicjoe23]

Our prerunner has a 400M and that thing runs like a raped ape. some good head work, cam and timing will allow the motor to open up and make really solid power. I would also say the same about our stock full but im not sure its actually a 400...

There's no question you can get good/great numbers out of an M-engine, but at what cost. . .

. . .I've seen the M-motors make really solid numbers in the Engine Master Challenge lately, but I don't know what the mileage on those numbers are and some of them are exorbitantly expensive to get the same numbers you could get for a fraction of the cost with an LS motor.

That being said I plan on sticking with a traditional Ford engine for my '79 because that's what I want to do and I have 3 old Ford engine platforms to choose from sitting in my garage. . .I could go with the 351/400M, a 429/460, or an FE engine; I just have to decide what I want to run. It will end being either the 429/460 or the FE because I don't think the M-engine will be able to make the same power as one of those two platforms for the same amount of money invested and I don't think there is gonna be much if any weight difference between them either. . .those M's are HEAVY for a "small block"!

[LENNY]

I can get a 400mutt done for about $6500 and I dont have to change motor mounts and trans mounts/drive line fuel pump and on and on!!!

[Dezertdisasters]

I can get a 400mutt done for about $6500 and I dont have to change motor mounts and trans mounts/drive line fuel pump and on and on!!!

You can do a 460 with super Cobra jet aluminum heads in that price range. The 460 and 400m use the same bell housing, all you need to change are the motor mounts, and you can get those from autofab. And I am pretty sure you would make more power than the 400m. You should talk to Total performance in Santee, they know their fords. And I am running 5.29 gears and don't know what kind of miliage I am getting, I know it is pretty bad though.

[LENNY]

You can do a 460 with super Cobra jet aluminum heads in that price range. The 460 and 400m use the same bell housing, all you need to change are the motor mounts, and you can get those from autofab. And I am pretty sure you would make more power than the 400m. You should talk to Total performance in Santee, they know their fords. And I am running 5.29 gears and don't know what kind of miliage I am getting, I m is it is pretty bad though.

Ya Ive allready looked at going that way but a 429/460 are wider and wont fit without some major mods and I would have to build new headers to fit in the tunnel,if I change motors Im going LS/4l80 way,
400 mutt $6500 ? MPG
460 $5500 motor mt/tube rework/headers ? $$$$$$$$$
LS/4l80 $13000 plus motor mt/tube rework/headers/fuel system ???? $$$$$$$$

[atomicjoe23]

Sounds like you should stick with the 400 for now if money is an issue. . .I don't MPG is gonna be "good" no matter what. . .

. . .I've seen LS motor desert trucks getting 4 MPG (at least that's the claimed MPG). . .based off of that 3.5 MPG with an M-motor isn't too far off base.

[LENNY]

Ive got somtjing going on?? I talked to a couple guys and there prerunners get down to 4 MPG only if they are on It hard,just crusing and on the pavement they are between 7 to 10 MPG

[atomicjoe23]

That's about what my '67 Pontiac with the Pontiac 400 in it gets. . .I know it's apples and oranges, but the cubes are the same and my hwy/cruise mileage is the same.

[BRINGTHERUCKUS]

Ill have to talk to my uncle to get the details on what we have done to the motor. it runs strong, and hasnt been gone through in over a decade.