difference between 2 & 4wd 351m/400
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difference between 2 & 4wd 351m/400
Ok. I have a 79 2wd F150 and I am going to take the engine out and rebuild it and put it in a 78 4x4 F150. Is there any difference between the 2 and 4wd engines. Also if the motor is a 351 how would i make it a 400. I plan on putting an Edelbrock intake and 650 cfm offroad carb, porting and polishing the heads, putting a set of headers, and a comp cam in it. Any recomendations on headers and cam. I want an engine that has a lot of low to mid end torque. Thanks
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From: spartanburg, SC
no difference.
400 balancer, crank, pistons, and flywheel make a 351M into a 400.
comp cams 255DEH cam works well with stock engines, with the ported heads, up the CR to 9.5 and use the 265DEH and weiand intake with good headers. Tq peak will be about 3,000 rpm and pretty flat from idle to 5,000 rpm.
400 balancer, crank, pistons, and flywheel make a 351M into a 400.
comp cams 255DEH cam works well with stock engines, with the ported heads, up the CR to 9.5 and use the 265DEH and weiand intake with good headers. Tq peak will be about 3,000 rpm and pretty flat from idle to 5,000 rpm.
Last edited by F150daniel; Jun 12, 2004 at 01:25 PM.
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From: iowa
the only differences are the oil pan, and the exhaust manifolds, and since you are using headers, that leaves only the pan you will need a rear sump pan for the 4x4 with the long pickup tube, and you need to replace one of the main bolts with one that has a stud to bolt the pickup tube onto.
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If I bump up the compression ratio to 9.5:1 will I still be able to run on 87 octane. I dont want to run over 89 octane but I would rather run on 87 since gas is $1.78 here at its lowest as of today. I just want an everyday driver that is a good off roader and mudder.
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From: iowa
Originally Posted by teederj2002
If I bump up the compression ratio to 9.5:1 will I still be able to run on 87 octane. I dont want to run over 89 octane but I would rather run on 87 since gas is $1.78 here at its lowest as of today. I just want an everyday driver that is a good off roader and mudder.
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From: WA
Originally Posted by fatherdoug
Why does the 4WD fuel pump have a different part number than the 2WD on the '78 400 engine? If I get one at the parts house they always ask if it is 2WD or 4WD?
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From: Billings, Montana
The only difference between the 351M and the 400 is the crank and pistons.
If you want 9.0:1 compression, I would use the highest octane gas the pumps offers.
If you want that compression you can get some flat top pistons which will run you about $150, or you can keep stock pistons and have the block decked to raise the cr.
The 265DEH Comp Cam will give you torque out the tailpipe.
If you want 9.0:1 compression, I would use the highest octane gas the pumps offers.
If you want that compression you can get some flat top pistons which will run you about $150, or you can keep stock pistons and have the block decked to raise the cr.
The 265DEH Comp Cam will give you torque out the tailpipe.
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From: (near) Denver USA
The only differences I've ever seen in pre-'80 trucks between 2wd and 4wd M-block engines is the oil pan/pickup tube and dip stick/tube.
In '77-'79 2wd trucks, the M-block (351M/400) engines use a front-sump oil pan, with the dip stick going through the block (on the front of the block, just to the right of the integral timing chain cover). This is the same configuration as used on all "car" applications.
In '77-'79 4wd trucks and all '80-up trucks (both 2wd and 4wd), the M-block engines use a rear-sump oil pan, with the dip stick going through the left side of the oil pan. On those engines, the dip stick hole in the front of the block is plugged with a press-fit plug.
Components that are different are: oil pan, oil pump pickup tube, dip stick, dip stick tube.
All M-block engines in trucks and vans (both 2wd and 4wd) use the same left exhaust manifold as car engines, and the same truck-only right exhaust manifold.
There is no difference in fuel pumps related to 2wd and 4wd applications. Ford catalogs show three M-block fuel pumps: '71-'79 car and '77 truck/van, '78-'79 truck/van, and '80-up truck/van.
In '77-'79 2wd trucks, the M-block (351M/400) engines use a front-sump oil pan, with the dip stick going through the block (on the front of the block, just to the right of the integral timing chain cover). This is the same configuration as used on all "car" applications.
In '77-'79 4wd trucks and all '80-up trucks (both 2wd and 4wd), the M-block engines use a rear-sump oil pan, with the dip stick going through the left side of the oil pan. On those engines, the dip stick hole in the front of the block is plugged with a press-fit plug.
Components that are different are: oil pan, oil pump pickup tube, dip stick, dip stick tube.
All M-block engines in trucks and vans (both 2wd and 4wd) use the same left exhaust manifold as car engines, and the same truck-only right exhaust manifold.
There is no difference in fuel pumps related to 2wd and 4wd applications. Ford catalogs show three M-block fuel pumps: '71-'79 car and '77 truck/van, '78-'79 truck/van, and '80-up truck/van.
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If I bump up the compression ratio to 9.5:1 will I still be able to run on 87 octane. I dont want to run over 89 octane but I would rather run on 87 since gas is $1.78 here at its lowest as of today. I just want an everyday driver that is a good off roader and mudder.
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