318 to 340??

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Demonyte

Demonyte

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Hey sorry everyone to strike this huge conversation. I don’t know what I was doing last night when I didn’t catch myself when I was saying “340” what I meant to say was 440. That will probably change a lot sorry.
 
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Only thing you might come across is balancing, what year model 340, if its a 72 up you will need a balanced torque converter or flywheel, other than that its a breeze.
 
Mopar-Mitch said:
Only thing you might come across is balancing, what year model 340, if its a 72 up you will need a balanced torque converter or flywheel, other than that its a breeze.
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It is a 1970 340. I don’t know if that changes anything.
 
Demonyte said:
There’s no difference in size? If not that would be super easy and nice! Thanks
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273 318 340 and 360 all pretty much the same size like said may have a different weighted balancer on the front or back and possibly the driver side l motor mount may need a little different set up for the 360 maybe, but I'm sure there others will chime in. it's not even worth thinking about if you got a 340 to put in there to replace a 318 any small thing you may have to do would be well worth it.
 
Easy enough though when you grab the motor get the motor mounts too! I assume it's going to come with its own harmonic balancer and flexplate and motor mounts?
 
The motor mounts are exactly the same. I don't understand why people keep repeating that bullshit myth. The mounts are ALL the same. Now, the motor mount engine BRACKET for the 340 and 360 are the same, meaning they are different from the 273 and 318. So, you will need the driver's side engine BRACKET for the 340 or 360, but the mounts are the same.
 
The 273 thru 360 are basically the same block externally, but have different bores and stroke to come up with the different displacements. The heads, manifolds valve gear, and torque converters vary. Most parts interchange, but some don't without without the right parts. Like the 360 Magnum heads use a slightly different intake bolt arrangement I believe. So go for it! Do some research before swapping heads, manifolds, converters etc.
 
Mopar-Mitch said:
Only thing you might come across is balancing, what year model 340, if its a 72 up you will need a balanced torque converter or flywheel, other than that its a breeze.
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'72 and '73 340's are externally balanced??? :realcrazy:
 
Mopar-Mitch said:
Yes, cast crank and weighted balancer and torque converter or flywheel.
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Not sure this is true. I did a cast crank '72 340 and it was internally balanced. I used a couple different neutrally balanced converters behind it without issue, using a standard flexplate.
 
318willrun said:
'72 and '73 340's are externally balanced??? :realcrazy:
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Sorta. Early 72s still retain the steel crank engine. The later ones got the cast crank engines from the latter half of 72 and 73.
 
RustyRatRod said:
Sorta. Early 72s still retain the steel crank engine. The later ones got the cast crank engines from the latter half of 72 and 73.
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yep, mine had a cast crank and was neutral balanced
 
RustyRatRod said:
Not if it was a 340. If it was neutral balanced, it was a steel crank.
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I tell ya, the best machine shop around turned that cast crank mains and rods, and it was cast. I promise ya I ran neutral balanced converters, without issue
 
318willrun said:
I tell ya, the best machine shop around turned that cast crank mains and rods, and it was cast. I promise ya I ran neutral balanced converters, without issue
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Then either one of two things. Either your machine shop doesn't know a cast crank, or you ran the wrong stuff. No 340 ever came with a cast internally balanced assembly. Cast was external, steel was internal.
 
RustyRatRod said:
Then either one of two things. Either your machine shop doesn't know a cast crank, or you ran the wrong stuff. No 340 ever came with a cast internally balanced assembly. Cast was external, steel was internal.
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Ok. LOL... the guy built indy 500 engines and didn't know a cast from forged crank. I guess I ran the wrong converter, and I put that smooth running 340 in a Demon, right in front of the original 318's converter and tranny, then I put it in a '70 truck, right in front of the original 318's converter and drove it from Illinois to Colo, then it went into a '72 Duster that had a neutral converter, till the car was sold. Purred like a kitten..... :)

Sorry, I had to be a little smart …. LOL.
 
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