383 / 440 balance question

[1967coronet]

If I pull my 1965 383 this spring and replace it with a 1976 cast crank truck motor 440 do I have to use the 440 flex plate ? I know I will need to use the 440s external balance converter but was not sure about the flex plate.
Thanks.

 

[IQ52]

If I pull my 1965 383 this spring and replace it with a 1976 cast crank truck motor 440 do I have to use the 440 flex plate ? I know I will need to use the 440s external balance converter but was not sure about the flex plate.
Thanks.

If factory, both of those flex plates will be neutral balanced. So you could use which ever one would bolt to your torque converter.

 

[69Bee]

Flex plate should be the same as long as the weights are on the converter, but if it is already on the 440 engine, what does it matter?

 

[1967coronet]

Thanks guys, both flex plates are factory Chrysler , I just was not sure if there were any balance issues between the two.

 

[BeepBeepRR]

I just purchased a SFI Flexplate for my cast crank 440. My machinist says I will need it. This is the one I bought. Its so I dont have to use a balanced torque converter. Is what he said. He said with this I can use whatever torque converter I want.

https://www.summitracing.com/parts/bmm-10237

 

[69Bee]

I just purchased a SFI Flexplate for my cast crank 440. My machinist says I will need it. This is the one I bought. Its so I dont have to use a balanced torque converter. Is what he said. He said with this I can use whatever torque converter I want.

https://www.summitracing.com/parts/bmm-10237

This is true, but I think that you could get a proper Mopar converter for a street application easily as the stall speeds are well supported. The many different racing units available, and probably price wise, this would be the way to go. It really doesn't matter as long a one or the other are balanced, and not both of them.

 

[Zeppelin264]

440 Cast Crank requires the B&M flex plate with a neutral balance converter.

 

[69Bee]

440 Cast Crank requires the B&M flex plate with a neutral balance converter.

That is not true. Either the original flexplate with a weighted converter, or the B&M flexplate with a non-weighted converter will work.

 

[BeepBeepRR]

That is not true. Either the original flexplate with a weighted converter, or the B&M flexplate with a non-weighted converter will work.

Right. The reason in my case is because I already have a B&M torque converter. I will also keep the original flex plate and I do have the original torque converter too. But yes the SFI is only required if you want to go with an after market converter that is not weighted.

 

[Zeppelin264]

Sorry, if you want an SFI rated flexplate then then B&M is your only choice.

 

[wyrmrider]

IDK of any other flexplates that are weighted except the B&M
BVVC as several different weights are needed for various crank combinations
#1 choice is to internally balance the engine
#2 is to loose 6 pack weight rods and heavy oem pistons
3 Prefer balanced flexplate to balanced converter due to variability and availability-
an unballanced converter is an unballanced converter-
a converter with balance weights is an unknown factor till you measure the size of the weights- and different diameter converters should take different size/ = different weights
so how do you easily change to a new different sized converter?
BTW most converter shops do NOT have a dynamic spin balancer- check and if not walk away
the machine has to hold the stator in place while spin balancing or you have a glorified tire bubble balancer
and out of balance is not linear with rpm- it's much worse