318 to 340 conversion

[HemiOrange70]

I have a 318 Challenger and I am putting in a 340. I understand the only things I need to do are:
-add weights to the torque convertor
-use different motor mounts
The wiring harness, pulleys and brackets are the same-correct???
as always thanks
 

[PlumCraZRT]

I don't know a whole lot about the small blocks, but I would imagine that everything would be the same except your 318 might not be internally balanced, whereas the 340 should be, so you would actually REMOVE weights from your torque converter.  If it were my car I would get a torque converter that is designed for an internally balanced engine.  Be aware the heads and intake are different on a 318 than on a 340.  You can put 318 heads/intake on a 340, but why would you?  I don't know if you have performance heads/intake in which case you have already taken off the 318 stuff and put "340/360 heads and intake" on.

[oldkimmer]

381s are all internally balanced,68-72 340s are internal, very late 72+all 73 340 will have a cast crank,...........kim.....

[PlumCraZRT]

381s are all internally balanced,68-72 340s are internal, very late 72+all 73 340 will have a cast crank,...........kim.....

I wasn't sure if the 318s were internally balanced... thought they might not be since they were not considered performance engines (ie no orange paint ).  I guess the later 340 engines weren't really performance engines either.  Nice input.

[Got JOB]

The motor mounts will work from the 318. The bracket on the drivers side will bolt up to the front ears of the block but the back ear wil require a spacer between the bracket and the mounting ear on the block. You can use washers, or a nut that will slide over your bolt threads. The passenger side bracket will bolt up correctly to the mounting ears.

[Super Blue 72]

You have to add this to your car somewhere.... 

[tactransman]

The motor mounts will work from the 318. The bracket on the drivers side will bolt up to the front ears of the block but the back ear wil require a spacer between the bracket and the mounting ear on the block. You can use washers, or a nut that will slide over your bolt threads. The passenger side bracket will bolt up correctly to the mounting ears.

that's exactly what I had to do in my Chally when I went from a 318 to a 360.

[HemiOrange70]

Thanks, the first thing I bought was the 340 emblem, even before the motor. So will I require weights on the torque convertor?? It is a 69-340

[tactransman]

Not if it is a true '69 (forged crank)

[chrisII]

unless somebody has messed with the 340 the only thing you nead for the swap is the left mount, or mess with the washers, spacers, and rubber mount not being straight (the later only in some cases)

[Bullitt-]

I'm NOT sure about this but I thoght that the kickdown linkage for a 2brl vs 4brl was different.     

[chrisII]

I believe it is, I have used 2bbl kickdown linkage, had to use spacers to raise up the bracket, then put a bolt and 2 washers through the linkage so it would kick down like it was suposed to. forgot about that one , sorry.