Flex plate

[furyus 67]

Do the small block and big block flex plates interchange? I've seen somewhere that they do but I cannot find the info again. What I have is 11" flex plate on my 413 and a 10" stall converter from the nyer that I bought. I'm wondering if the flex plate off of my 318 will work on the 413. Thanks

 

[Landyacht]

You can get a heavy duty flexplate from 440 Source with the holes for multiple bolt patterns and it won't cost you all that much . I am pretty sure that the flexplates are interchangeable between big blocks an small blocks. I know that Summit racing lists their flexplates as interchangeable. Check out 440 source first. You might reconsider.

 

[furyus 67]

I found the ones online! I'm probly gonna have to bite the bullet and buy. After a lik more research I found out the 904 and the 727 used different flex plates. I have a 904 off of my 318. Booo

 

[Yatzee]

Regardless of whos flex plate you buy, be sure to get an SFI certified one to be sure of decent quality. You can buy pretty cheap China reproductions but it's not like you change them every year so buy a good one. SFI ones are tested to very high r.p.m.'s ensuring they don't split or fly apart under heavy load. This type of plate is especially important when using a multi-fit with extra mounting holes because cracks always start at the holes. They are also well balanced and flat and straight. Who knows, maybe down the road you might install a higher stall torque convertor and a quality plate will definitely be required.
This is not a place to cheap out.

 

[Landyacht]

I found the ones online! I'm probly gonna have to bite the bullet and buy. After a lik more research I found out the 904 and the 727 used different flex plates. I have a 904 off of my 318. Booo

I had to edit my post. I originally wrote Mancini racing by mistake when I really meant 440 Source . I hope you caught that.

 

[furyus 67]

I had to edit my post. I originally wrote Mancini racing by mistake when I really meant 440 Source . I hope you caught that.

Mancinis does have them tho! But yea. 440 source and summit was the first 2 places I looked.
I'll definitely look for none China made Yatzee I appreciate the guidance though . I get a sick feeling when I have to use something made in China!

 

[furyus 67]

Does anybody know what the difference is between a 904 flex plate and a 727?

 

[polara71]

Does anybody know what the difference is between a 904 flex plate and a 727?

My youth taught me there were two sizes of flex plate but I dont know if that was 904 to 727 or sb to bb

 

[66/440]

727 small block and big block are the same. Different bolt pattern for 904.

 

[70bigblockdodge]

I can't see how a 904 is different but I am not a small block guy so my 904 experience is limited.

 

[furyus 67]

I'm dropping the trans in the morning so I'll find out. I've laid it on top of another big block/727 that I have and the only difference I see is the diameter. The Crank bolts match up perfectly, so I'm assuming the TC bolts must be off some how.

 

[70bigblockdodge]

Crank bolts are the same from /6 to 440-6 pack only the Hemi has 8 bolts.

 

[furyus 67]

Here's what I've got . The bottom,larger is 383/727 the top smaller is 318/904.

 

[68plymouth383]

I've had small converters in my 727 before that use the small flex plate. The larger diameter converter uses the bigger flex plate. Both 727 transmission.

 

[furyus 67]

I've had small converters in my 727 before that use the small flex plate. The larger converter uses the bigger flex plate.

That's what I thought. Then somebody threw a monkey wrench or should I say Mopar wrench and told me the 904 flex plates were different than the 727. Right now I've got 2 large 727 flex plates and 1 small 904 flex plate and 2 small converters.

 

[68plymouth383]

I can only speak for the 727. If both flex plates bolt up to the big block crank that means it'll work. A 904 trans will not mount to a big block engine. But i dont think the flex plates are different. holes on the converter are clocked. The convertor needs to be in the right position for the holes to all be straight. Line your flex plate up, and turn it till it fits right.

 

[furyus 67]

The trans will be out in the morning. I'll know then!

 

[MrMoparCHP]

Looking at the parts book they have two numbers, it doesn't say which transmission but looking at the engines I would say the difference is the trans and not the engine.

The 273 has one number, 440 one and different than the 273, the 318 both.

So any 904 will work on any 904 ady any 727 will work on any 727.


Alan

 

[furyus 67]

Thanks Mr.MoparCHP. Well I pulled the trans out and in turn have utterly confused myself. The crank bolt pattern on the 318/904 flex plate is of course the same. So for shits and giggles I thought I'd try to bolt 904 flex plate to the 727 torque converter and it bolted up to that too. Now, if it bolts to the crank and it bolts to the TC it seems to me that it would work in my car. What is the difference? I put a straight edge on the bell housing of the 904 and the 727 and measured the depth of the TC lugs, they were the same. I laid the big block flex plate on the concrete along with the 318 flex plate to check the depth at the crank and they were the same! I cannot find a reason (with in reason) that the flex plate that came off my 318/904 won't work on my 413/727. Did they make a run of 7 or 8 flex plates that will fit both and I found one? SMH...

 

[furyus 67]

That pic is the "904" flex plate bolted to the 727 TC.