I plan on converting my 340 Dart from a 4-speed to a 727 automatic this coming winter. I know the small block automatics came with a support bracket on each side of the bellhousing. I have TTI headers and from what I have read, apparently the brackets won't fit with headers. What I would like to know is, will not having the brackets be an issue?

No, unless you're producing ungodly amounts of torque with sticky tires, a suspension that plants them and loose converter

Myself I'd leave the 4 spd in it.

In my experience the driver side brace still fits with headers, but the passenger side is a no go.

I don't think they are needed personally. but I guess the factory must have thought they were needed, why else would they spend the money on them? But on the other hand, you would think a 4 speed would see higher shock loads than an auto, and yet there are no bellhousing with provisions for those braces.

Had TTI headers on mine and ddin`t have the brackets on mine with no issues.

It has been my experience that more small blocks are missing them than have them and they never seem to have any problems.

The drivers side one especially gets tossed when the starter is replaced by the longer version which won't clear it.

I believe I heard from a reputable source the reason was, one the higher level driveline executives had a relative with a metal stamping company that wasn't doing to well. The relatives wife was involved in uhh ARRANGING the contract, LOL

TJP, that makes sense!

Unless you have the 727, I would go 904, it would need a different driveshaft than the 727, but I would not put a 727 behind a small block. I just changed from a 727 to a 904 and all said and done will have picked up 2.5 to 3 tenths. Now, I increased my flash rpm by 300, in the same dia converter. Both were PTC 9.5” converters. I also changed to the low gear set inside the 904. I also went aluminum for the driveshaft. So it is not just your typical 727 to 904 swap, but no more 727’s for me. Just not necessary. As an added benefit a much lower risk of shattering the drum.

Because the SB isn't a skirted block like the BB, more of the bellhousing extends below the block with no support; that's why the factory added the struts.

This isn't the race forum and no asked about picking up a tenth.

I still like my line of ?

True, but he’s running headers so he probably isn’t a restoration/date code/part number guy. If he has nothing on hand there is no reason to run a 727, except if he cares that it might have come with one originally. Racing or not, do you want to run a less efficient transmission? More power to the wheels, better mileage, safer, comparable cost. Valuable info no matter what you are doing with the car.

agree

Unless you are planning Dukes of Hazzard jumps, the small block will survive just fine without the extra support brackets. I ran a lot of SB Mopars with an auto on a dirt track, all without the extra brackets, and never had a single issue. I can almost promise you are not going to put your Dart through what those old dirt track cars went through.

As to the 904/727 deal. If both are box stock transmissions, the 727 will hold up much better under abuse then a 904 will. If the trans is being built, then the 904 can probably hang with a box stock 727, but if both are being built, the 727 is a very tough trans and can take a lot of abuse.
I tend to kill auto transmissions. Its 727s for me. I've killed way more 904 then I ever killed 727s, and I've had more 727s.

Of course, your mileage may differ.

Not a numbers car nor stock in appearance/build but it is an original 340 car so I would assume had it originally been an automatic it would have had a 727. I do already have a stock 727 I planned on using and I do plan on putting a shift kit in it. I don't think I'll bother with the brackets

My car runs 10.0's with no braces or issues.

You will have to spend $$$ to make it live behind the 340, unless it's a show poodle you are just driving on and off a trailer .

I think, all 340’s came with 727’s originally, but could be wrong. My 68 340 did. You have the 727 then it is probably the way to go. Doesn’t take anything really exotic to make a 904 live at a pretty serious power level, but as stated above, your mileage may vary. Two more things you need to address with a 904 than with a 727. Pump drive and high gear clock spring, (if you are going to spin it a bit) Billet servo’s? probably good idea for both, quality steels clutches?, both. Billet lever? Really depends on the valve body/line pressure. Sprag? Rebuilt 904 is good for most street car apps. 727? You want the best one you can get. Billet drum? Not really needed in 904. Good quality bands for both. If you really search for the best price, not much more than a comparable 727. If you are going through the transmission, the cost difference to fix the most common issues isn’t much more than a totally stock rebuild for either transmission.

So what? The 727 is more than sufficient to handle a 340. The same cannot be said about a stock 904. Safer? Not stock it ain't. Comparable cost? Not finished it isn't. maybe a core to build is comparable in cost but a stock 727 is all that is needed to handle the load, a 904 needs lots of costly parts to do the same. To be honest, if I was going to make the mistake of putting an automatic in place of a stick it wouldn't be either the 727 or 904 varieties. I'd get one with an OD gear.

If it's for race and speed use a 904/998/999. If it's a cruiser with a 340 or 360 and you want durability use 727.