904 Flex Plate for '72 340

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65Vart

65Vart

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I'm putting a built 904 behind a 72 340 (CudaCox old motor). Does anyone have the pt. number for the weighted Flex plate I need? The convertor guy said its a better option then adding weights to the convertor.
 
B & M 10234 is the correct one but is no longer made.
The 10235 for the 727 will bolt up o.k. but there isn't a lot of clearance.
Most say it works o.k.
 
Summit lists B&M 10239:

http://www.summitracing.com/parts/bmm-10239/overview/make/dodge

and

TCI 102390

http://www.summitracing.com/parts/tci-102390/overview/make/dodge

as being for external balance and 904.

I have no experience with those flexplates, or a 904 for that matter, so I can't say for sure, but might be worth looking into.

EDIT: No, they're not necessarily cost-effective options, but you didn't say if you needed SFI-approved or whatever, so... might be worth checking out anyway.

EDIT 2: Also, you cannot go by Summit's pictures, at least not for their flexplates, so don't go by the visual. I know this from experience. I recently ordered a $40 TCI one, a $60 Hughes one, and a $10 ATP one for 727 internal balance. They all looked totally different on their visual, all had different pricing obviously, but were all 100% identical in every way once they arrived. Two of them were just overpriced re-labelled stock flexplates.
 
ir3333 said:
B & M 10234 is the correct one but is no longer made.
The 10235 for the 727 will bolt up o.k. but there isn't a lot of clearance.
Most say it works o.k.
Click to expand...
Does the 10235 not have the dual bolt pattern? I'm already running a mini starter.
 
72Dodge said:
Summit lists B&M 10239:

http://www.summitracing.com/parts/bmm-10239/overview/make/dodge

and

TCI 102390

http://www.summitracing.com/parts/tci-102390/overview/make/dodge

as being for external balance and 904.

I have no experience with those flexplates, or a 904 for that matter, so I can't say for sure, but might be worth looking into.

EDIT: No, they're not necessarily cost-effective options, but you didn't say if you needed SFI-approved or whatever, so... might be worth checking out anyway.

EDIT 2: Also, you cannot go by Summit's pictures, at least not for their flexplates, so don't go by the visual. I know this from experience. I recently ordered a $40 TCI one, a $60 Hughes one, and a $10 ATP one for 727 internal balance. They all looked totally different on their visual, all had different pricing obviously, but were all 100% identical in every way once they arrived. Two of them were just overpriced re-labelled stock flexplates.
Click to expand...
These are both 360 flexplates
 
65Vart said:
These are both 360 flexplates
Click to expand...

What is the difference between that and a 340 external balance flexplate? Sincere question here, I don't know. I thought external balance was external balance...? Is it the amount of weight distribution, or....? So, it's important to get a 340-specific one and not use a 360 one? (Thank goodness I'll probably never build a 904 since I have 3 small block 727's already, but I still want to know!)

Thanks
 
72Dodge said:
What is the difference between that and a 340 external balance flexplate? Sincere question here, I don't know. I thought external balance was external balance...? Is it the amount of weight distribution, or....? So, it's important to get a 340-specific one and not use a 360 one? (Thank goodness I'll probably never build a 904 since I have 3 small block 727's already, but I still want to know!)

Thanks
Click to expand...
From what I've read there is a difference.
 
yes...the 340 requires a difference flex plate due to the difference in balancing weights.....

the balancers are not interchangeable out of the box...

the question...do you have a cast or forged crank?
 
Gotcha, thanks for the info! I truly didn't know. Just trying to help, and got helped in the process!
 
70aarcuda said:
yes...the 340 requires a difference flex plate due to the difference in balancing weights.....

the balancers are not interchangeable out of the box...

the question...do you have a cast or forged crank?
Click to expand...
Cast crank for sure , has the external balanced harmonic.
 
65Vart said:
I'm putting a built 904 behind a 72 340 (CudaCox old motor). Does anyone have the pt. number for the weighted Flex plate I need? The convertor guy said its a better option then adding weights to the convertor.
Click to expand...
Hi Wally...I ran a stock flex plate with a 2500 stall with the weight on it with no problems.The converter was purchased from The Converter Man in Toronto.Just sayin :D
 
10235 has 2 bolt circles in 5/16 and one in 7/16
Petty ...your saying the converter from the converter had the weights on it..
 
65Vart said:
I'm putting a built 904 behind a 72 340 (CudaCox old motor). Does anyone have the pt. number for the weighted Flex plate I need? The convertor guy said its a better option then adding weights to the convertor.
Click to expand...

Your converter guy doesn't have a balancing machine? Sounds like a guy to avoid.
 
I have the b&m 10235 on my cast crank 340/904 combo.
Old style starter hits it when engaged. Put a starter off a 95 magnum and works fine.
 
So we fired up the 340 today. Have a slight vibration at idle. My buddy who is helping me with the install automatically says its the flexplate. I ordered the right one b&m 10235 for sure. Any ideas would be great .
 
you have a vibration using the 10235 on your cast crank 340?
are there any weights on your torque converter?
 
there is something else going on here,that is the correct flexplate for a cast crank 340.
perhaps the crank has been changed?
 
I'm kinda in the same situation here. I have a mildly built 340 and 727 trans. So please tell me if I'm wrong but can you get a 340 balanced flex plate (the B&M one everybody is recommending) to replace the factory one and get a converter without the weights on it? I'm really heaving a hard time finding a converter balanced to a 340. I have a Hughes performance now that's pretty nice but I'm looking for a higher stall speed.
 
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