LA vs Magnum engine - what's the diff? 340 or 360?

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AUS_Duster

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Hi there. I need some advice...

I have a 70 Challenger T/A clone. The 340 is running the six pack set up, but is tired and ready for rebuild. I want to build a stroker engine and retain the stock external appearance and the six pack. This is where the questions start...

Should I choose a 360 over the 340 just for the extra cubes. Is there a difference with the blocks or heads? Will the intake manifold bolt onto the 360? Is one inherantly stronger\better than the other?

What is he difference between the LA engine and the later Magnum? Is everything interchangeable like heads, bell housing, intake manifold etc? Will my six pack, transmission etc just bolt up to a magnum block?

Any advice greatly appreciated.
 
Don't mean to be brisk, the 'search' function will yield you great results on this topic.
 
If your building a stroker 340 has the biggest bore there for it will be bigger than the 360 when stroked, around 414cid with a 0.030" over bore.
 
The 360 is often the best bang for the buck. If you are going for the 340 or 360 stroker, the 340 will make a 414 and the 360 will make a 408. I could about bet that if the build were similar, you'd never be able to tell the difference in power at all between a 408 and 414.

360's are cheaper to obtain than a 340. 340's are more desirable and command a bigger price.
The 360 will produce much more low end power due to the difference in stroke. The 360 has a 3.58 stroke while the 340 is at 3.31. I guess you need to decide if you want the rpm monster that is a 340 or the low end power that is the 360. Torque is king on the street though!!

The difference on the Magnum's are mainly...
*Hyd roller cam and lifters (some late 80s LA's were roller though)
*Different intake and different heads (although with some pieces- they will bolt to an LA)
*Separate mounted rockers (1.6 ratio)

I'm sure there is something else I'm leaving out...

Remember that the 360 and the 5.9 are externally balanced which requires a specific balancer and flexplate or converter)..

You could always build an LA/Magnum hybrid (LA with Magnum top end). The Magnum heads are the same between the 5.2 and 5.9. They flow extremely well!!
 
Stroke the 340, eddy heads, high lift 280ish hydraulic roller, six pack and headers.
 
Heads are interchangeable but have different intake bolt holes.Magnum heads probably flow better than the older regular 1.88 valve heads but the x heads on stock 340's flow pretty good.Since you already have a 340 then dont waste your money buying a 360 mainly if you are looking at stroking it you will actually lose alittle by stroking a 360 over a 340.Your 340 may have the forged crank in it also which will not work in a 360.With everything you've said I would say stick with the 340 and build it.
 
AUS_Duster said:
Hi there. I need some advice...

I have a 70 Challenger T/A clone. The 340 is running the six pack set up, but is tired and ready for rebuild. I want to build a stroker engine and retain the stock external appearance and the six pack. This is where the questions start...

Should I choose a 360 over the 340 just for the extra cubes. Is there a difference with the blocks or heads? Will the intake manifold bolt onto the 360? Is one inherantly stronger\better than the other?

What is he difference between the LA engine and the later Magnum? Is everything interchangeable like heads, bell housing, intake manifold etc? Will my six pack, transmission etc just bolt up to a magnum block?

Any advice greatly appreciated.
Click to expand...


the six pac will not bolt on to magnum heads.....the magnum heads can be redrilled or new replacement magnum style heads(EQ head or Indy X heads) can be purchased with LA intake bolt pattern.....magnum intake bolts are vertical..LA come in at an angle...

transmissions will bolt up...
 
Thanks for the replies. I think I will go with rebuilding the 340. Indy x heads are also a good suggestion. Any suggestions on where to source striker crank/rods etc?
 
Scat, k1, eagle (these first three offer 4" strokes), or BPE (?) for the big boy stroker of 4.25" stroke. Either way just make sure the crank you order is forged.
 
Purchased a forged steel rotating assembly from Scat cranks for my 360. Very knowledgeable salesman. Told him what I had, what I wanted to do with it and he put together a balanced rotating assembly for me. $2000 US. He shipped it to pembina North Dakota free I drove down and picked it up. Well packed no damage and everything went together and FIT PROPERLY WHOO HOO. The forged crank is internally balanced so I had to buy a harmonic balancer from scat also and used a 340 style flex plate.
 
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