Performance out of a 400

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Redneck86

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I'm gonna be in the market for '78-'79 Bronco soon, use to have an '86... pretty much hated it but still kinda loved it (first truck) Tend to be more of a GM guy but have a soft spot for Broncos and High Boys. This is my old profile from when I had the '86 but now I think it's time to get my long awaited '78-'79 Bronco.

(Preferably a '78 w/400 backed by NP435/NP205, I think the round headlights look meaner, I like rowing my own gears and what's not to like about the 205? My '79 K20 has the Muncie465/NP205 and I love it)

Now my question, building a 400. I'd like to have one that makes around 400-450 horses and 500 ft lbs. First thing I've noticed along the lines of Forged Pistons, Rods or Cranks for the 400 is there ain't any. I'm aware that you get custom made pistons so that's not an issue. But what about cranks and rods? Even on a mild build I don't like cast parts. Would I be better off going with a 429? If I do an engine swap it'd be a 429, everybody sticks a 460 in theirs... I gotta be little different so for me it's a built 400 or 429

 

Rons beast

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Hey Red,

Welcome back.

There's a reason you can't find forged pistons, rod or cranks for the 400. It just isn't a good choice for a build to get the kind of HP and torque you want.

If you can find one go with the 429, and find a place like Summit, or Jegs that will work with you to get the heads camming, and intake, exhaust that will work together to get you the HP you want.

If you're looking for torque, ( which is what most guys want and need to make a heavy Bronc move), Then you go with the 460. ( that's why the others did.) The 460 has a longer stroke than the 429. Both have the same bore. Everything equal- Longer stroke= more torque

BUT....also tell them what your intentions are with the truck. Your plans for the engine MAY not be what you need to achieve your goals.

I have seen and heard from others that put a kings ransome in an engine, and got crappy results

Good Luck

 
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Redneck86

Redneck86

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I may just end up going with a 429... would've liked to do a 400, just because it's what came in the truck. But it's looking the 400 is just boat anchor like the 351M <_< Would've thought somebody would've built something out the M blocks. The L&L swap kits seem like a nice deal, pricey but nice and straight forward, so I may just go that route. What are the stock cranks in a 429/460? Cast or Forged?

 
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Rons beast

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Hey Red,

The cranks are cast. There may have been some 429 Hi-Po /race variations that had forged cranks, but I can't say what applications off the top of my head.

Forged cranks are great, but unless you're beating on it and revving the thing to it's limit you are ok with a cast crank.

 
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Redneck86

Redneck86

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I was afraid that was gonna be the answer <_< Is there anywhere making stock stroke 429/460 forged cranks? So far all I've found are Eagle cranks with longer strokes pushing the engine to over 500 cubes. That ain't a problem, just more then what I'd ever need out of it. A 513 or 545 would definitely be something not everybody else's Bronco has, way beyond badass... just a lot of overkill. I do plan to stick with a Dana 44 and 9" too, built up and geared lower of course

 

Rons beast

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Hey Red,

what are your plans for the truck? Looking for a forged crank may be overkill as well. My experiance with forged cranks was using them for high RPM race aplications. I never needed a forged crank in something I was using on the street. Crank throw and gear ratio have to be all put into the equation to make the truck usable for it's intended purpose.

example Long stroke, forged crank, big bore, low gearing = tractor pull, rock climbing stuff

You have to match the gearing to the engines power/ rpm range. You can build the rig for muddin, rock climbing, pullin, and it will be a pita on the road. Gotta define your use for the truck.

 
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Redneck86

Redneck86

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My plans? Hmm, to lift her enough to run 36s, build the axles up gear them low (4.11 or 4.56) Detroit out back (not sure of the front) build a Damn strong V8 for her. The reason I don't like cast parts, I've seen them fail on mild builds before. If I have to go with a longer stroke crank to a have forged one, build a 513 or 545... I will, I have no problem running that under the hood (who would?) **** then rest of the engine could be milder, if I have to go that route. Streetability don't really concern me... I've rolled 4.88s on the street before, long as it'll still barely go down the road I'm fine. Basically I want the truck to do good in mud, rocks, hill climbs, snow or whatever I point her at. It probably will be something most anybody else would absolutely hate to drive down the road :rolleyes: Guess that's why is my truck and not yours <_< I've never minded sacrificing Streetability for go :D /emoticons/[email protected] 2x" width="20" height="20" />

 
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Rons beast

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Hey Red,

I hear ya on being confident nothing is gonna brake. Sounds like your set on the forged stuff. Nothing wrong with that. Still consult with the folks at places like Summit, or Edelbrock, they will steer you to the components that will work with your build.

You know what you want. That's good. Some folks want the off roading truck, then complain about the lack of mileage, or poor road performance.

Good luck, and let us know how the build progresses.

 
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Redneck86

Redneck86

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Yea I'm pretty stuck on going with forged for anything I build, if I'm spending good money for a motor it's worth to me to spend the extra and know it'll hold up and be stout. Much appreciated advice bud, I'll definitely keep y'all up how the build goes. Thanks

 
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Red Green Jr

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Dont know where your build is now, but ill try to talk you back into the 400.  I built a pretty mean 400 last summer out of a 351M, and NAPA and oreilly's sells forged cranks for the 400, i re-used the stock forged 351 connecting rods.  Tmeyer inc makes tons of parts for builds like this and plenty others.  I just went with cheap cast aluminum pistons, theyre fine so far.  What really made my engine a beast is a Cleveland cam, the 400 is torque monster when built properly, its got a 4in bore and 4in stroke, while the 460 only has a 3.85in stroke.  The cam i used is a comp cams XE-256H-10, its got a semi-choppy idle and really opens up the 400 with excellent response and torque, the power is through the roof!  In my opinion the 460 is a boat anchor that sucks more gas than the boat.  Get a high performance cam with a carb and intake, maybe mill the heads and you can get 500 ftlbs and 400hp "theoretical" easily.  Ive got a c6 so ive got quite a bit of loss and i can still out pull a 460.  With a manual tranny and anything above 3.51 in the rear end and that 'theoretical" turns pretty damn real.

hope i convinced ya

 

79fordblake

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Actually a lot of people are building the 351M and 400 these days. The 400 especially can throw down some really good numbers and be reliable. Give a look at Tmyers website or better yet call him. This guy turns 400s from boat anchors to monsters everyday.

With that being said the 351M in my 78 Bronco is in really bad shape and I decided to bite the bullet and I went with a 460. Its still waiting to go in. It has a mild build on it. I don't think a mild 400 would want to go against it.

I have a stock good running 400 in my 79 Bronco.

 
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elkslayer

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looking to make a 400 out of my 351m.  need to change the pistons and crankshaft?  put in a reman not knowing it was a 400. Damn I miss that motor.   My question is the heads, the ports matched the felpro 1240 intake gasket to a t.  showed no signs of porting or head work. what would they have been? 

 

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