Flex Plate?

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J

JDPdart

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I swapping Motors from an la 318 to a Magnum 360 in my race car and was wondering what flex plate do I need? The trans is a 904 I have the factory flex plate from the 360 it was in a 4x4 truck if that matters, the converter is a dynamic 8 inch with the lager bolts. I heard that i could use the factory one if i drill out the holes and oblong one of them. I'm planning on running mid to low 11's so i didn't know if the factory one would hold up.
 
Get an sfi approved flex plate,tci/b&m if you get a tci make sure you remove the coating around the crank flange.
 
tci/b&m do not make a 5.9 magnum to 904 flexplate . Use the stock one or have the weights for the magnum welded on to the converter....The 5.9 magnum external balance is different from the LA 360.

there is a web site from a member here that covers the flexplate issue with the Magnum.......

Dodge Magnum 5.9 Flexplate

Automatic Transmission Details

got to love google
 
Now with your 8 inch converter..I agree that the bolt holes might not line up and are the 5/16 not the 7/16 as the race converter will be.
 
Could I use a 727 flex plate and just elongate a hole i read on other forums about that?
 
JDPdart said:
Could I use a 727 flex plate and just elongate a hole i read on other forums about that?
Click to expand...
727 and 904 use the same flex plates from the factory. I don't have a NHRA rule book, but wonder if a non SFI plate on an 11 sec car is legal?
I know that others have done it before, but the thought of drilling out the mounting holes to 7/16 and then elongating one hole doesn't sit right with me.
 
LA and Magnum are external balance but different weight. B&M Magnum to 727 used with a 904 bolts up but the starter will hit the edge of the flexplate when you try to install it.
I ran a OEM with one elongated hole, 7/16 bolts high 11s 1.65 60' with no problem. After you elongate the unsymmetrical hole you can weld up the open side and dress it up.
 
moper makes a weight kit for converters p/n 4120241 if you can't find any luck elsewhere.
 
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