340 to 360 Engine Swap

Hello all,

I have a Cuda that was born with a 340 and 727 transmission. I pulled the original 340 engine and 727 transmission to keep in a safe place since they are numbers to the car. I recently bought a 1972 360 and a small block 727. They were bought separately so they were never married. I do not have the flexplate or torque converter so I want to know what I need to do to make sure everything doesn't shake apart. Thank you for the help in advance!

Paul

Hello. I've used the b&m flexplate with a standard convertor for a 727. It works excellent.

Doesn't the converter need to be balanced to match the 360 rotating assembly since it is externally balanced? I know my 340 converter didn't have any weights on it but I have seen 360 converters with.

B+M sells a flex plate that will allow a zero balance convertor to work behind the externally balanced 360...

the B&M specialty flex plate does exactly that same function, not dead on like it would be if you handed the rotating assy and this flexplate & front dampener to your shop for balancing but it duplicates Ma's factory torque converter balance which is so so but adequate. Order one & you are set. the 340 MAY have slightly different front to rear spacing of the block mtr mt lugs on the DR side so it MAY take a different mount. the 360 will have a different dampener and pan & other than that they will be externally the same AFAIK. there are (2) "center" sump 360 pans that I am aware of, a 392 and a 876 (stamped on bottom). the sumps on both are ~8" long and the sump bulge starts 4" back from a vertical plumb line straight down from the very front lip on the 392 and 2" back on the 876. both take different pickups (I can dig up pics if needed). grab your tape & measure the 340 pan before you pull it

I believe you can use the 340 engine mounts on the 360, but not the other way around. My challenger had a 318 which I swapped with a 360 and I want to say that I spun up a small aluminum spacer to make up the width difference. I'll try to check tonight when I get home, if I can find the mount. Car's in pieces right now, but I think I know where the mount is.
I concur with everyone else on the B&M flexplate. I internally balanced the backside of my 360 so I wouldn't have to worry about special flywheel/flexplate/torque converter balance, but the aftermarket flexplate is a decent piece. Converter bolt holes may be a different size than stock, but I don't know this for sure.

340 and 360 mounts interchange. Oil pan doesn't, but if your donor was a pass car then it should work.

Other than oil pan and external balance, they are a plug and play swap.

So, I have a torque converter with weights on the face and without. Just confirming that I should use the converter with NO weights of the face with a B&M flexplate P/N 10236. http://www.bmracing.com/products/10236-c...query=flexplate

Thanks for all your help guys!

a 360 "weighted" converter will have 2 weights close to each other on the front flat face. any converter may have a thinner weight on the curved back side & reason is that the weight on the curved back side is used to balance the hunk of metal that the converter is when mfr'd to a neutral balance then if it is going to be made into an externally balanced unit for a 360 then 2 weights are additionally added to the front flat face. EDIT yes use a TC with NO weights on the front along with the B&M plate for external balanced setup

Some 360LA converters have a single large weight, usually triangular but sometimes square.

If you have a converter with weights on the front, you don't need to buy a B+M flexplate.

Maybe, depends on what it's weighted for. Not all external balance Mopar engines use the same imbalance weight. Assuming the weights you have are right is not a good idea.

After I posted my reply I happened to think of that. He also stated he has a 904 in the car now and if weighted converter he has is for a 727, it won't fit his 904. My bad.

No problem, it's all good