Cast or forged crank

[Matt13]

So, thanks to a generous board member, I have a forged crank and a cast crank. Forged needs machining cast is ready to go. Preferences? I'm going to try to rebuild my 1972 340 to 68-70 specs and  hp. Thanks

[MoparLeo]

Building a standard stock spec 340, save the forged crank. Cast is plenty good for up to 400hp. Just have a good balance done on the complete assembly. And of course mag the crank first.

[Cuda Cody]

Forged 340 cranks are getting super hard to find.  Like Leo said, get it magged first.  I had to buy 3 forged 340 cranks to find 1 good one.

[7212Mopar]

You need to decide if you want to go internal or external balanced engine. Cast crank in later 340 block is external balanced. I prefer internal balanced engine and don't have to deal with external balancer, flexplate or flywheel.

[RUNCHARGER]

Not an external balance fan which is whats a cast crank is. You have to ensure you have the correct torq convertor and front balancer. Just get the forged crank machined (then you will know it is right) and install it with neutral balance convertor and balancer.
There is a 340 cast convertor, a 360 cast convertor, a 400 cast convertor etc. etc.

[mopartaz]

i would run forged crank for serious street/strip duty. But i've also known stock eliminator guys running 360's who have had hundreds of passes on their cast crank engines. Do you have the rest of the parts for the build? (balancer etc) Wasn't there a discussion on stroker crank builds? If I were to do it all again today I would get a 360 and a stroker kit ( forged) good rods, good aluminum heads, roller cam  and run it. So much cool stuff now than 20 years ago.

[Chryco Psycho]

You can run the cast crank using lighter pistons , lighten the rods & have it internally balanced also .

[tparker]

If you're asking which to put in if you have both, I would say forged. But @MoparLeo has a good point. If you're not building a 450+ HP motor and plan on pushing it, you might want to consider saving the forge for another project or person. If this is the only car you plan on doing, the it probably doesn't matter. I was considering which to go with for my stroker. I ended up going with cast because I will be within it's recommend HP rating and I won't be seriously racing the car other than the occasional getting on it and a few trips down the strip... if our local strip survives much longer.

[Chryco Psycho]

My first choice would be a stroker kit with a new crank already balanced
second choice would be use the cast but have it internally ballanced IF the balancing is reasonable , make sure you use lighter pistons
3rd choice use the steel crank & make sure it is balanced correctly for the piston weight & know you can beat the daylights out of it assumeing the oiling is good .