MJ's 71 Beaver (Dart)

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mj's friend

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gilbert az
This will be the official build thread for MJ’s 1971 beaver (supposedly demon dart). Long story short, mj is my work buddy. We work at a turbine engine overhaul shop in az. I’m a mechanic and he was one of my inspectors. He just took a job in management so he has less time than ever to make a build thread. I told him I’d make the build thread and he will chime in when he’s not looking down the barrel of a shotgun contemplating his recent career move. We’ll probably pester you guys with stupid questions within this thread. Feel free to pound the keyboard in anger with caps lock on, we won’t be offended.
dart front.jpg

dart ***.jpg


The car had a slant 6 and auto that we just pulled out. The car is in decent shape. We’re just working on getting the mechanicals in order. No cares for body work at the moment and the interior is just fine for now.

The donor engine/trans combo going in is a 383 and going with a 440 source stroker kit/stealth heads and a 727 trans that’s gonna be gone thru. The motor seems to be a 1969 with 906 heads. It was said to have had a spun rod bearing. It did indeed. The Shumacher slant 6 to BBM mounts recently arrived. We'll probably dump the bare block in to test fit and notch the k member.
383.jpg


The rear was a 7.25” or whatever tf, no one cares. Mj picked up a fully built 8.75”, 3.23 ratio with new suregrip and 5x4.5” axles and a 7290 yoke . Don’t ask how much it was but it’s beautiful and it’s A body dimensions. Driveshaft will be measured once the motor and trans are in the car. Rear suspension will likely be caltracs and split mono leaf springs from calvert as well. Wouldn't mind sticking with rear drums but we have nothing to start with as of now so suggestions are welcome.
axle housing.jpg
diff.jpg


Here's the aluminum radiator that was in it with the slant 6. The question is will it be big enough for the big block?
rad width.jpg
radiator depth.jpg


That's it for now, I just wanted to get this thread going. We'll have questions and want opinions on front suspension, disk brake conversion, subframe connectors, engine/trans stuff... Just pretty much everything. So far 440 source seems like a good vendor for engine components. P-S-T for suspension rebuild and Brakes. Shumacher for the mounts.

Any and all advice is welcome, even if its "sell it all to save your marriage, buy a street bike instead!"
 
Nice! I just received Schumacher mounts about a month ago for my 340, they were scarce. Haven't fitted them yet. Cool build!
 
How much crank you putting into the 383? The radiator may be okay if it's got the 1 inch (or are they 1 and fractional, I forgot?) pass tubes in it. But in Arizona, it may take a 3 row radiator with large pass tubes, and a high flow water pump such as a FlowKooler or PRH.
 
Looks like a great starting point. Not too many unmolested 71/72 Demons around anymore.
For those that don't know the BEAVER was the other name that Dodge was thinking about using.
Glad the Demon name won .
As far as cooling the 383 you might get by with the radiator you have, but may find the lower hose is on the wrong side.
 
Love Demons, looks to be a solid foundation for a great sounding build. 65'
 
It looks like a great project and in the right hands. My 71 demon was also born a 6 cylinder but now has a 318 and I have been unhappy with the feel of it at highway speeds. I had a 6 cylinder Demon in high school and I don't remember it being scary to drive. I got a lot of good suggestions when I posted a question but one in particular got my attention. Apparently these cars came with a front sway bar when equipped with a V-8 (someone may correct me but that was my take on it). I just received a Hellwig sway bar and plan to install it this week in hopes it will tighten up the front. It may be something to consider with that monster you are installing.
 
Nice! I just received Schumacher mounts about a month ago for my 340, they were scarce. Haven't fitted them yet. Cool build!
Yeah I saw they had a lot that were out of stock. We were lucky the slant 6 to bbm a-body motor mounts were one of the few in stock
 
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How much crank you putting into the 383? The radiator may be okay if it's got the 1 inch (or are they 1 and fractional, I forgot?) pass tubes in it. But in Arizona, it may take a 3 row radiator with large pass tubes, and a high flow water pump such as a FlowKooler or PRH.
I’m thinking I have mj talked into the 3.75” stroke (434” iirc). I like a good rod angle. And not clearancing the block. Keeping 255 drag radials somewhat planted to the ground will be difficult no matter what with a warmed over big block, the 496” rotating assembly seems excessive.

as for the radiator I’m not sure about the internals, I didn’t look at it too hard. I think we’ll give it a try and just keep a close eye on the temp gauge.
 
It looks like a great project and in the right hands. My 71 demon was also born a 6 cylinder but now has a 318 and I have been unhappy with the feel of it at highway speeds. I had a 6 cylinder Demon in high school and I don't remember it being scary to drive. I got a lot of good suggestions when I posted a question but one in particular got my attention. Apparently these cars came with a front sway bar when equipped with a V-8 (someone may correct me but that was my take on it). I just received a Hellwig sway bar and plan to install it this week in hopes it will tighten up the front. It may be something to consider with that monster you are installing.
Interesting. We’ll be going in with the bigger torsion bars but a swaybar is not out of the question. Luckily the heads will be lighter and I think the rotating assemblies from 440 source claim to be lighter than factory components as well but it’s still gonna be a pig with the big block in the front.
 
Good luck! Any AC in that garage????
It’s not bad yet. I’ve lived here my whole life and done motor swaps on 117* days with no ac and it sucks. But it’s doable (iTs a dRy hEaT). I’m hoping this motor isn’t ready until September or later. We still need to get rear suspension and brakes under it and rebuild the front susp and convert to disk before we get to excited about engine work.
 
It’s not bad yet. I’ve lived here my whole life and done motor swaps on 117* days with no ac and it sucks. But it’s doable (iTs a dRy hEaT). I’m hoping this motor isn’t ready until September or later. We still need to get rear suspension and brakes under it and rebuild the front susp and convert to disk before we get to excited about engine work.
S E TEXAS! It ain't the heat that kills ya, its the humidity (and lack of wind!).
Yea dry heat as in a friggin OVEN!!!!!!
You know the humidity might be just a little high, when the sweat has run off ya balls and your boots are soaking WET!!!!:poke:
 
Apparently these cars came with a front sway bar when equipped with a V-8 (someone may correct me but that was my take on it).

Correct me if I'm wrong, but my '71 slant-six Demon has a front sway bar. Was it an option? Maybe standard with front disc brakes?
(sorry, no better pic)
sway bar.jpg
 
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Fender Tag Option Code S31 is 70-71 only for front sway bar. I would think maybe it's part of a towing package, or suspension upgrade. or someone added it later on. I see you have power disk brakes which may have been part of this upgrade. Check your fender tag and or build sheet if available.
 
Fender Tag Option Code S31 is 70-71 only for front sway bar. I would think maybe it's part of a towing package, or suspension upgrade. or someone added it later on. I see you have power disk brakes which may have been part of this upgrade. Check your fender tag and or build sheet if available.

:thankyou:
No S31 code on the fender tag, nor on the build sheet.
But the number 39 in the "FT S/BAR" build sheet box (fourth line)

Front sway bar 39.jpg
 
Not sure of the year but around 1975 on the big block Cordoba/Charger the lower hose is on the passenger side. You may try from 75-(78 the last year) for a big block water pump housing . Don't quote me on this but maybe.
 
Not sure of the year but around 1975 on the big block Cordoba/Charger the lower hose is on the passenger side. You may try from 75-(78 the last year) for a big block water pump housing . Don't quote me on this but maybe.
This is why we’re here
 
Interesting. We’ll be going in with the bigger torsion bars but a swaybar is not out of the question. Luckily the heads will be lighter and I think the rotating assemblies from 440 source claim to be lighter than factory components as well but it’s still gonna be a pig with the big block in the front.
Hmmm. bigger torsion bars... not a bad idea
 
Not sure of the year but around 1975 on the big block Cordoba/Charger the lower hose is on the passenger side. You may try from 75-(78 the last year) for a big block water pump housing . Don't quote me on this but maybe.
Your correct, I did the below.
440 source offers a pass side inlet water pump housing
They sure do and I did it myself. The housing and pump made of aluminum saves a lot of weight.
Hmmm. bigger torsion bars... not a bad idea
I ran my 400/727 w/ the /6 bars. It’s not what I’d recommend but it was something I got used to quickly.

@mj’ s friend
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(WTF is going on here?)
both if need be here… LOL!

I also used a Summit racing aluminum radiator. It made the stock fan a no go. Watch your thickness on the radiator.
 
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