318 vs. 360 balance?

[doogievlg]

I got a call from a guy switching from a 318 to a 360 and he asked if he will need to get the new flex plate when doing the swap since the 318 is internally balanced. To my knowledge the flex plate is needed and is the easiest thing to do in the swap. Am I correct or does he just drop in the motor and go?

 

[moper]

yo uare correct - he needs the correct 360 weighted flex plate. Or - he needs the 360 factory convertor for the trans he has.

 

[moparlover]

externally balanced engine (i.e. 360)
1. harmonic balancer is not neutral... it has offset weights or drilling and is specific to the model (340 cast crank balancer is different from the 360)
2. on the back end you need an offset weight or drilled flex plate (b&m style) or a torque converter with weights. (NOT both. one or the other)
most use the B&M flexplate so that they can just use neutral torque converters. it makes purchasing easier.
if you use the stock flexplate (neutral) then you need to hunt down torque converters with offset weights welded on, or weld your own on. it's much easier to get the B&M flexplate and use a neutral-balance (unweighted) torque converter

 

[doogievlg]

Thanks. So does he need a new harmonic balancer too?

 

[67Dart273]

Thanks. So does he need a new harmonic balancer too?

Balancer needs to match the engine

And are we talking about a 5.9 Manum or a 360LA? Both are externally balanced but both are different from each other

 

[Plymouth Power]

If you're switching from 360/727 to a 318 and leave the same transmission in the car do you need to switch the torque converter? Or will it all balance out if you get one of those liquid harmonic balancers?

Such as; http://www.summitracing.com/parts/flu-720301/overview/make/dodge

What do you guys suggest?

P.S. both are LA's.

 

[moparlover]

the flex plate or the torque converter attached to the 360 will be weighted. (not neutral balanced).

so no you cannot just use it on the 318. you might be able to remove the weights if the tc has weights on it. you are better off finding a neutral balanced converter and flex plate to work with a 318.

the balancer on the front cannot be used to offset the rear.
a 318 harmonic balancer is different than a 360 balancer.

again for an internal balanced engine, the balancer, flex plate, and torque converter are all neutral balanced. (318 is internally balanced.) none of the items should have bob weights or halfmoons cut out or anything like that.

externally balanced engines (340 or 360 or 400 or 440 with cast cranks) use a engine specific balancer (360 is different from 340 is different from 400 is different from 440) and the flex plate OR torque converter will have an offset/weights (but not both of them)