1972 Demon with 71 340 casting

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Bigbeaver

Bigbeaver

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Hi all, I have a 72 Demon that I have owned since I was 16 years old (for 30 years) that I have recently restored. I was always under the impression that it was the original 340 with the car. As I have become a little more educated on A bodies through this site, have started digging into it more and it appears that may not be the case. The casting on the block reads 1 18 71, which I assume means casted on Jan 18, 1971 (photo attached). Is this definite proof that this is not the original 340 for the car? Is it possible to have this early of 71 motor in a 72 car? Can't say I would be disappointed as I know they dropped the compression / valve size / HP in 72. Thanks for your time.

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Yes. I would say a casting date that early compared to the car's year model means it's not the original engine. Are you SURE the car is a 72?
 
Simple enough to verify. Find the machined pad on the passenger's side of the engine. It's about midway of the engine just above the oil pan rail. It will have a partial VIN. If it matches the VIN on your car, it's the original engine. It's not impossible it's original, but I'd say it's unlikely.
 
That is not what you go by to tell if it’s matching numbers. It should be cast in 71. I think on drivers side of your block right above your oil pan is a flat pad. It will have your sequence number which is the last 6 digits of your vin. That’s what you go by. If not on drivers side it’s on passenger. Pretty sure drivers. That’s pretty early though.
 
moparker said:
That is not what you go by to tell if it’s matching numbers. It should be cast in 71. I think on drivers side of your block right above your oil pan is a flat pad. It will have your sequence number which is the last 6 digits of your vin. That’s what you go by. If not on drivers side it’s on passenger. Pretty sure drivers. That’s pretty early though.
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Good to see you on here. Been worried about you. I've left a message or three.
 
Thanks fellas, I will dig into it a little more when I get in tonight. Always amazed how guys are so willing to help on here. My apologies RustyRatRod, been using the site often but haven't logged in in a while. Catching up now and I will keep you posted on what I find out.
 
Had to slip out of work to check this out. So the numbers were on the passenger side engine, just above the oil pan and the 6 digits match the last six on the dash VIN (numbers matching). Everything about the car screams 72 from the dash, emblems, marker lights, rib on trunk, grille, hood and hood hinges, bumpers. As mentioned the 340 is stamped Jan 18 71. I suppose anything could have happened between 72 and the early 90s when I got my hands on it and redone as a 72? From what I see you can’t pull the year from the VIN. Anything else I can check to confirm it may really be a 71. Maybe the motor and VIN pulled from a 71? Thanks again

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Sure looks like you're original block to me... casting dates don't mean much at all...under the drivers head on front of block you will find the engine assembly date. That matters much more. I've seen some large spreads on 340s between casting and assembly.
 
Thanks, so do you think the casting date indicates that the 340 would 10.5:1 compression motor or the bogged down version in 72 with the 8.5:1 compression
 
By 72 all 340s had low compression...by all accounts , yours should be low. It has a 72 vin on it...and it's original to your 72 car
 
Bigbeaver said:
Had to slip out of work to check this out. So the numbers were on the passenger side engine, just above the oil pan and the 6 digits match the last six on the dash VIN (numbers matching). Everything about the car screams 72 from the dash, emblems, marker lights, rib on trunk, grille, hood and hood hinges, bumpers. As mentioned the 340 is stamped Jan 18 71. I suppose anything could have happened between 72 and the early 90s when I got my hands on it and redone as a 72? From what I see you can’t pull the year from the VIN. Anything else I can check to confirm it may really be a 71. Maybe the motor and VIN pulled from a 71? Thanks again

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And there you have it. It's the right engine for the car. I would have thought not based on how big a date split from the car it is, but with Mopar, you never say never.
 
Dutchrebuild said:
By 72 all 340s had low compression...by all accounts , yours should be low. It has a 72 vin on it...and it's original to your 72 car
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Nope. They did not. This occurred about April 1972. Early 72 engines still had steel cranks and higher compression. The later 72 and 73 engines did not.
 
Bigbeaver said:
Thanks, so do you think the casting date indicates that the 340 would 10.5:1 compression motor or the bogged down version in 72 with the 8.5:1 compression
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Maybe the higher compression engine. You need to see what the build date is. As I mentioned above, the changeover to the cast cranks and lower compression began "about" April 1972. All the rest of the 72 engines from there and the 73s had cast cranks and lower compression, so yours may still have the steel crank and higher compression.
 
Dutchrebuild said:
Sure looks like you're original block to me... casting dates don't mean much at all...under the drivers head on front of block you will find the engine assembly date. That matters much more. I've seen some large spreads on 340s between casting and assembly.
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Me too, but I've never seen a spread this big. Maybe in a **** movie. lol

We've seen it now though, because that's the correct engine for the car.
 
72 model year cars were built starting in Aug 1971 IIRC. 6-8 month lead time isn't that big of a deal on a block. They didn't do just in time inventory, stuff got brought in and stacked. If it sat in the corner for a bit as newer casting came in, that's where it sat.

Stamping looks like original engine.
 
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I wasn't around "back in the day" but I can tell you a 2, 3, or even 4 year old block may get built into a current engine in today's OEM world. It has to do with how engines are expected to be needed and if sales don't support the projections, then the casting run of blocks sit around waiting to be consumed until another batch is made. I won't name RPO's but this is common for the lower volume engines today.
 
Thanks, some good information. Does the balancer give it away? Pulled this picture from another thread and my 340 has the forged balancer shown in the picture if correct

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Bigbeaver said:
Thanks, some good information. Does the balancer give it away? Pulled this picture from another thread and my 340 has the forged balancer shown in the picture if correct

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Then there you go. If it doesn't have a vibration when running, it's a forged crank and also likely the higher compression engine. Congratulations. It's a boy. lol
 
It is perfectly normal for your block to be a 71. That’s how they all are.
 
Looks like a 72 motor to me...2 is first digit...you got lucky and got a early engine
 
I worked for mother mopar for years. It was not uncommon for the above situation to happen. Engines could be 90 to 150 days built prior to installation. Remember that 72 was when the "EVIL EMPIRE(EPA)" reared its ugly head. On another note, RRR was pretty damn close on his steel/cast crank date. Below is an insert from the 72 parts book. Sorry for the way it reads. I am not a photographer. Dated April 20,1972.

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Was your engine originally blue but sprayed orange sometime later??
 
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