400 - keep or replace?
Thread Starter
|
Laughing Gas
Joined: Apr 2013
Posts: 1,092
Likes: 32
400 - keep or replace?
So, found a truck with the 400m, 4 speed, 4x4, long bed ranger. Guy said it has a rear main seal leak and a couple other problems, nothing that seems major.
Is the 400m a problematic engine, or is it pretty solid if I give it a bit of TLC?
I could put in a 300 I6, but I would rather have a V8.
Is the 400m a problematic engine, or is it pretty solid if I give it a bit of TLC?
I could put in a 300 I6, but I would rather have a V8.
Cargo Master
Joined: Apr 2009
Posts: 3,038
Likes: 4
From: South west Idaho
I have had a few in the past and had good luck with them. You can make a few mods which i never did and they help more i understand. I wish i had one in place of my 302 but it's got an AOD transmission . So i will leave well enough alone .
Hotshot
Joined: Feb 2004
Posts: 10,726
Likes: 2,584
From: The Shenandoah Valley
No question in my opinion, I'd keep the 400 and any effort I would have spent towards swapping in a 300 six would go all the way to a refreshed 400 if needed. Won't get as good gas mileage as a 300 but more power more torque. A 400 is like a 300 six plus two more with better flowing heads being readily available. Both have same bore & stroke.
A 300 six makes lots of torque at low speed when compared to a same size V-8 (302) ..... but a 400 is easy to make into a real torque monster. If you want great mileage, you need a 300 six and 5 speed and likely a newer truck will have both.
A 300 six makes lots of torque at low speed when compared to a same size V-8 (302) ..... but a 400 is easy to make into a real torque monster. If you want great mileage, you need a 300 six and 5 speed and likely a newer truck will have both.
Senior User
Joined: Jun 2014
Posts: 351
Likes: 7
From: Plumas Lake, CA
For what it's worth
My 77 F250 was originally a 400 2V truck. I could not imagine cruising it around with anything less. The 351M (this is all hearsay because I have never owned one) is pretty much a steaming pile of *****. The 400 (Same block different stroke as the 351M) is the better of the two.
I guess that you need to ask yourself, what will I be doing with the truck and how much power do I need?
I am happy to have the 460 in my truck. Not happy enough though because I am constantly upgrading the power plant for no apparent reason. So, long story short, you may be happy with the 400, especially if you were going to throw a 300 in there. You will find these trucks never seem to be totally finished so, if you chose to build the 400 to a little better performance and fix the minor stuff on it, there is nothing stopping you from putting a fresh 429/460 on the engine stand for later.
I guess that you need to ask yourself, what will I be doing with the truck and how much power do I need?
I am happy to have the 460 in my truck. Not happy enough though because I am constantly upgrading the power plant for no apparent reason. So, long story short, you may be happy with the 400, especially if you were going to throw a 300 in there. You will find these trucks never seem to be totally finished so, if you chose to build the 400 to a little better performance and fix the minor stuff on it, there is nothing stopping you from putting a fresh 429/460 on the engine stand for later.
Postmaster
Joined: Jan 2013
Posts: 3,512
Likes: 3
From: Panama City
Bill,Bill,Bill (sigh)
The 351m is a fine engine for what it is. A dependable, torquey, long lasting engine. Do away with the retarded timing gears and it actually starts to breathe. Throw a good cam,intake and exhaust on it and it performs quite well.Is it a fire breathing drag race motor? No it was never designed to be. Will it outlast a fire breathing 351 windsor that alot of people rave over? Chances are it will. Ford made literally millions of these and put them in everything from 1 ton trucks to mid size sedans. Everyone loves a 351 cleveland right? Legendary Ford hi performance engine. Guess what? The lowly 351m uses the same head design as the 351 Cleveland. It can be an excellent performing engine. Just takes some research to find parts to do it with.( Well not as much as it used to since Tim Myers started building them) You can also buy a set of 400 pistons and 400 crank and turn the lowly boat anchor 351m into a 400. With not alot of money or work its easy to get 350 hp and 420 ft/lbs of torque out of 1. And that aint too shabby. Because it will still run forever if you dont try to turn it 7 grand.
The 351m is a fine engine for what it is. A dependable, torquey, long lasting engine. Do away with the retarded timing gears and it actually starts to breathe. Throw a good cam,intake and exhaust on it and it performs quite well.Is it a fire breathing drag race motor? No it was never designed to be. Will it outlast a fire breathing 351 windsor that alot of people rave over? Chances are it will. Ford made literally millions of these and put them in everything from 1 ton trucks to mid size sedans. Everyone loves a 351 cleveland right? Legendary Ford hi performance engine. Guess what? The lowly 351m uses the same head design as the 351 Cleveland. It can be an excellent performing engine. Just takes some research to find parts to do it with.( Well not as much as it used to since Tim Myers started building them) You can also buy a set of 400 pistons and 400 crank and turn the lowly boat anchor 351m into a 400. With not alot of money or work its easy to get 350 hp and 420 ft/lbs of torque out of 1. And that aint too shabby. Because it will still run forever if you dont try to turn it 7 grand.
Hotshot
Joined: Feb 2004
Posts: 10,726
Likes: 2,584
From: The Shenandoah Valley
I'll only add that a 400 is just a more torquey 351m, often with near the same mileage being returned.
Trending Topics
Cargo Master
Joined: Dec 2008
Posts: 3,209
Likes: 320
From: SW PA
My old 400 made 240rwhp/355rwtq on a mustang chassis dyno.
We tuned my buddy's truck the same day that had a 416 FE with ported CJ heads and way more cam and his made 277/400.
Both trucks had t18/np435, NP205, D60, and 32-33" tires.
I was pretty happy with that basic 400.
We tuned my buddy's truck the same day that had a 416 FE with ported CJ heads and way more cam and his made 277/400.
Both trucks had t18/np435, NP205, D60, and 32-33" tires.
I was pretty happy with that basic 400.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Ford Super Duty: 5 Things Owners LOVE, 5 Things They LOATHE!
Joe Kucinski
Every 2026 Ford Truck Engine RANKED from WORST to FIRST!
Michael S. Palmer
The Best F-150 Deal of Every Trim Level (XL through Raptor)
Joe Kucinski
Thread
Thread Starter
Forum
Replies
Last Post