Cool. Thanks. I don't remember WHERE I saw April, but somehow it's always stuck out in my mind. I wish other things would too. lol
1972 Demon with 71 340 casting
- Thread starter Bigbeaver
- Start date
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Really? Now you're learnin me somethin. lol
Yes, I heard of a couple high compression 340s in 72 cars but never seen 1 in person. But I have seen atleast 20 low compression 340s with steel cranks in 72 cars. In fact I was one of the lucky ones to own a 72 340 swinger in the early 80s but I didn’t know that at the time. Sadly it has been sitting under a tarp in a garage ever since I sold it in the early 80s. It was pretty decent shape then but no idea what it is like now. Kim
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It makes sense when you think about it, because 72 was the year they changed from gross HP rating to net. Thanks for that.
Bigbeaver
Member
Don’t know originally, but I remember my dad pulling it in the 90s and paint it blue. Painted orange by me shortly after as a kid.
Use up those steel cranks in 72! 
How did they go about getting the lower compression ratio? Did they not all have flat tops
No. The 68-71 (and some early 72) had a small dome on the piston that achieved positive deck height and gave the higher compression. The later 72 and all for 73 engines had 4 eyebrow flat tops.
oldmopardude
Well-Known Member
i have a 72 roadrunner 340 engine sitting on a stand, but never paid much attention to the changeover,, thanks for the heads up.
regarding early blocks in later cars, I helped junk out a 1974 charger R/T 440, and it had the 440 with casting date of jan 1971. Apparently there was a bunch of extra blocks lying around in 74, so they used them up. I still have the differential and original exhaust manifolds from it lying around somewhere.If we had known that being one of 370 or so would matter later, we would not have salvaged it. But, it was in 1984, and a dead title car. so,,,,
I forgot to mention, my friend had this engine and 10 others lying around when he passed.
I inherited his stuff, and I sold that engine to a guy in western nebraska for his 74 GTX. That was in 2018.
Wayne never sold engines!
regarding early blocks in later cars, I helped junk out a 1974 charger R/T 440, and it had the 440 with casting date of jan 1971. Apparently there was a bunch of extra blocks lying around in 74, so they used them up. I still have the differential and original exhaust manifolds from it lying around somewhere.If we had known that being one of 370 or so would matter later, we would not have salvaged it. But, it was in 1984, and a dead title car. so,,,,
I forgot to mention, my friend had this engine and 10 others lying around when he passed.
I inherited his stuff, and I sold that engine to a guy in western nebraska for his 74 GTX. That was in 2018.
Wayne never sold engines!
I have casting year October 71 block and lower assembly. Since it was assembled in 72 would that still have a good crankshaft to hang on to? I was gonna possibly toss it since I bought a new 4” stroker crankshaft?
Newbomb Turk
Well-Known Member
OP, do you know what that car is worth IF the VIN on the block matches the VIN on the car????
You might be shocked.
I was the second owner of a 72 340 4 speed Demon. It was dead stock down to the air cleaner.
Being young and ignorant I went racing and tore **** up.
The value in that car was the VIN on the car was for 1972 but this car was early 1972 and it came with 2.02 intakes and a steel crank and 10.5:1 pistons!!!!!
What that means is you can run at least one class, maybe two classes Loews in Stock Eliminator.
You’d be legally, LEGALLY running against engines with smaller valves and less compression.
You’d at least be damn competitive.
You might be shocked.
I was the second owner of a 72 340 4 speed Demon. It was dead stock down to the air cleaner.
Being young and ignorant I went racing and tore **** up.
The value in that car was the VIN on the car was for 1972 but this car was early 1972 and it came with 2.02 intakes and a steel crank and 10.5:1 pistons!!!!!
What that means is you can run at least one class, maybe two classes Loews in Stock Eliminator.
You’d be legally, LEGALLY running against engines with smaller valves and less compression.
You’d at least be damn competitive.
It likely has the forged crank.
What do you know of the history of the car? It is indeed the correct block for the car per the numbers. Could it possibly have been rebuilt before you owned the car and if so, what was put into it parts wise? Being that the car and drive train are over 50 years old, there is no telling what is in it internally.
My 340 was built using these pistons.
Sealed Power 428P30 Sealed Power Cast Pistons | Summit Racing
I guess it's safe to assume it doesn't have the stock 10.5:1 compression form the factory anymore.
No sir, I don't think it does. Those appear to be the late 73 and 73 pistons. But that's not necessarily a bad thing.
The motor was originally built in California hence the possible reason being only 91 octane gas availability. No worries though. Thanks.
As stated above, low comp pistons were flat tops with 4 eyebrows.
I put a set of std bore ones in a 360 and had to take about .020 off them and have notches cut in them to make everything clear.
I put a set of std bore ones in a 360 and had to take about .020 off them and have notches cut in them to make everything clear.
Take heart. Plenty of low compression 340s have won their socks off in stock eliminator.
Bahahahaha, yea mine won’t……
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