Filling an empty engine bay -- 383/400 vs 440 fitment in 71 Roadrunner

[Midnight_Rider]

Hey all, new to the forum. I need some advice. I recently bought a 1971 Roadrunner project car. Right now I have no block, cranks, heads -- nothing, starting from scratch. It was originally a 383 car.

My inclination is to go with a 440 but I wanted to kind of run this up the flag pole for some opinions from people who have experience... this is my first big block Mopar, and first Mopar period in many years.

Are there any 'gotchas' to watch out for with the 440 as opposed to the 383/400 platform? I guess mainly I'm wondering if one has more issues with exhaust clearance than the other. I like headers for performance but I'm not married to the idea if manifolds will get me where I want to be. And I'm also planning to swap out the power steering box for a Borgeson, so that should give a bit more clearance on the driver's side?

Thinking either Performer RPM or Holley Street Dominator for the intake, depending on hood clearance. Open to suggestions/alternatives though. It is a non-ram air hood. I'm assuming the low-deck engines will have more clearance here?

Thanks in advance for any input.
-Doug

[lukedukem]

i have a 383 in my 69 charger and i love it just fine. its not a speed machine, but it is reliable and it drives good.

Luke

[John_Kunkel]

Welcome to the board.

Since the RR engine compartment is the same as the GTX and the GTX came with the 440, there will be no fitment issues with any BB motor you choose.

I prefer the 440 simply because it's bigger and the cost to build it isn't that much more than a 383/400. I like the idea of the Borgeson box, definitely a worthwhile upgrade. Headers are a PITA for the performance gain, I'd stay with HP manifolds.

[RallyeMike]

A common stoker motor is the 400 with a the 440 crank making 451 cubes. It will look like a stock 383 but have 440 performance. you could still run your 383 hood decals and nobody would be know. This gives you a little more hood clearance if you choose to go with a hi-rise intake, and it does provide marginally better header fitment, although be prepared for headers to be a pain either way.

[Midnight_Rider]

I am struggling to make a decision on the engine. Actually I'm struggling with all the decisions -- engine, transmission, color...    Right now I've got a blank slate on everything.

I'm planning on going to check out a couple of engines this weekend. Guy local to me has a 383, a 400, and 2 440's. All would be non-running cores/rebuild candidates.

I know the low-decks would leave a little more room underhood and save a little weight, and wouldn't cost much more to stroke. And that's appealing. The 440 would probably give me everything I need power-wise and have factory rod ratios & compression height for long-term reliability. And that's also appealing.

At this point I'm leaning toward a 440. I won't be racing the car. I just want a nice cruiser with as much HP/TQ as I can get while still keeping good streetability & longevity. I just don't have the first-hand experience with the 451/470 combos to know if I'm going to a) need that much power on street tires that won't hook anyway and/or b) end up with issues that cause premature wear.

[BSB67]

451 is so nice.  You can maintain the rod length and have a very light piston.

[Midnight_Rider]

451 is so nice.  You can maintain the rod length and have a very light piston.

No concerns with longevity/piston rock on a street motor with the shorter piston?

The 451 kit from 440 Source shows a 1.32" compression height. The 470 kits list pistons with a 1.480" or 1.485" CH, but with a shorter 6.535" rod. I have no idea at what point CH becomes an issue... or rod ratio either, really.

[BSB67]

Stock rod, 1.32 CH.....perfect!

[Midnight_Rider]

Well... I picked up a 440 today, so we'll see how big of a shoehorn it takes to get it in the engine bay once I get the proper motor mounts, oil pan, and exhaust manifolds or headers. It came complete but it's a 74 vintage out of a motorhome, it's my understanding those peripherals are different? I'll have to get a trans/crossmember too.

Thanks to those that replied -- I gave the 400/stroker idea serious consideration but in the end I got the whole 440 locally for not much more than the 400 block alone would have set me back. Guess if I do a stroker it's going to be a 493+... I'll have to take some time to educate myself, ask questions and formulate a plan of attack.

[RallyeMike]

You can leave the shoe horn in the closet. The car was made for the 440.

Other than mentioned, to use the motorhome engine you may need to change the water pump housing to have the lower hose be on the correct side, and you'll also be looking for the right bracketry to mount your accessories.

[Midnight_Rider]

You can leave the shoe horn in the closet. The car was made for the 440.

Other than mentioned, to use the motorhome engine you may need to change the water pump housing to have the lower hose be on the correct side, and you'll also be looking for the right bracketry to mount your accessories.

Thanks for the info.

This engine came dressed with an alternator, PS pump, fan and a bracket for AC (minus compressor), plus pulleys and belts. Are they going to be different for a 74 truck/MH vs a 71 car? (I have a lot to learn on my Mopar stuff).

I guess if it works, it works... and the block isn't correct for the car anyway. But I'd still like it to look like it belongs there.