73 318 to 340 Engine Swap: What's Required?

[Road_Runner]

I've read here and/or elsewhere that one or both of the motor mounts have to be changed to put a 73 340 in a 73 318 Barracuda.  Anyone know the details and what else if anything should be changed to be correct?  I've got a set of 340 iron exhaust manifolds if I don't go with headers, obviously the block/heads/intake are different, but what about the accessories?  My 318 has PS, PB, Cruise & A/C which I was planning on swapping over.  I've also got a 340 kickdown setup if I stay with the automatic (undecided).  I'm thinking most everything will swap from one engine to the next, but again not sure about the motor mounts.

Thanks in advance, Jim

[Chilly]

 As far as I can remember the mounts are the same. You'll have to change the torque converter if staying with the auto do to the weight that is required to balance the motor. 318 has no weight, 340 has a small weight and the 360 has a larger one.  All your external parts will swap over to the 340 as long as they are both LA motors, 

[Chilly]

Hey Roadrunner, I think I made a mistake on the motor mount issue, I know when I converted to a 360 from a 318 I had to buy a bracket for one side. I can not remember which side it was. Sorry for the wrong information.

[Cooter]

Hey Roadrunner, I think I made a mistake on the motor mount issue, I know when I converted to a 360 from a 318 I had to buy a bracket for one side. I can not remember which side it was. Sorry for the wrong information.

That's the 360..The 318/340 I believe are the same engine blocks, just cast with different bores and numbers.

I'd be more concerned about the 1973 340 With cast crank and balancing problems from the internal balance 318...

[Chryco Psycho]

the 340-360 use a different left bracket for the engine mount

[Road_Runner]

the 340-360 use a different left bracket for the engine mount

Thanks everybody, this is what I thought I read before.  Chryco, does left mean passenger side? (never know whether people are talking about left & right as you face the engine, or as you face from the driver's seat.)  If anyone has a picture of the 'different' mount that would be awesome, too.

Thanks again, Jim

[Road_Runner]

One more thing, does it matter whether the 340 mount is from an A,B or E body?  Are they the same?  Are they the same if they are at least for a 73? 

Thanks again, Jim

[Cooter]

Some of 'em in 1973 went to the "Spool" mount (Mostly A-body) which was different from the "biscuit" mount..

[Road_Runner]

Some of 'em in 1973 went to the "Spool" mount (Mostly A-body) which was different from the "biscuit" mount..

Looks like I have some more research to do!  Thanks to all of you I know I need something different, still not sure what though!  No problem, I'm just trying to gather all the necessary parts before I start doing the machine work on the 340.

Later, Jim

[Chryco Psycho]

The mount is moved slightly forward on the block I believe .... so ti is possible to shim the 318 mount to line up , to get the correct mount you need the sandwich mount not spool so A & B body up to 72 , E body up to 74 .
 If the 340 is still being built I recommend you swap to the 318 steel crank which are common & have the rotating assy internally balanced to eliminate all the hassles with trying to find & or balance a flywheel . or stroke the 340 out to 412 ci & have everything balanced internally !  The auto is slightly easier as you can get a balanced converter but I still to internally balance as it will be far more accurate than betting on the converter

[Road_Runner]

The mount is moved slightly forward on the block I believe .... so ti is possible to shim the 318 mount to line up , to get the correct mount you need the sandwich mount not spool so A & B body up to 72 , E body up to 74 .
 If the 340 is still being built I recommend you swap to the 318 steel crank which are common & have the rotating assy internally balanced to eliminate all the hassles with trying to find & or balance a flywheel . or stroke the 340 out to 412 ci & have everything balanced internally !  The auto is slightly easier as you can get a balanced converter but I still to internally balance as it will be far more accurate than betting on the converter

Thanks Chryco, I now know what to look for mount-wise.  As far as the engine goes, I haven't even started yet, just gathering parts.  I got the 340 as a rebuildable short block, supposed to be std bore with a forged crank (seller pointed out something about the crank counter-weights that indicate its forged).  I definitely like the advice to internally balance and will absolutely go that route.  I'm considering my options whether to go stroked or not.  I like what I hear about how high-winding the 340s are, weighing that against the extra torque & HP from the bigger motor. 

One more question, when you said the left mount is different is that the same as the passenger or driver side (that's how some mounts I've found are listed)

Thanks again, Jim

[Chryco Psycho]

left is left side , all part #s are odd on the left side & even on the right unless the parts fit both side , anyway to clarify left is always drivers side not standing in front of the car looking at it

[Road_Runner]

left is left side , all part #s are odd on the left side & even on the right unless the parts fit both side , anyway to clarify left is always drivers side not standing in front of the car looking at it

Learned something new today, thanks!