904 help - help an Aussie!

[nasty VJ]

I was hoping that somebody could explain the difference between the 904 that was used behind the slant 6 engine and the one used behind a smallblock. (Thats if there are any!)

Also, can anyone recommend which one to use and what modifications are recommended to handle 350 HP?

All advice gratefully accepted

[JVMopar]

The starter location is different on the /6 904 vs the sb 904. I do not believe that there are any internal differences between them.

[6packdart]

one out of a trk has wider 1st an rev band a little lower gear in 1st dont get into the lockup trans not wirth the hassels ,. the case is diff ,just the starter location all else the same i think i'd have to look in the book one has one more clutch than the other but i do believe it is the diffbetween a lock up an a non have any ? i have the manual on it ill scan what you need best i can do . an there 100lbs lighter than a 727 an hold the 400 hp i have i'v broke a few but thats life . in your v/8 what ever it might be i also run a /6 convertor stalls bout 2200 .at the trans shop it cost me about 45$for a convertor an about 80 $ for a master rebuild

[nasty VJ]

Thanks for the replies!

I'm actually using a locally made conversion kit to put one behind a 265 Cu. IN. Hemi 6 cylinder (yes - you read that right, it is in an Australian Charger).

I have a website where you can see pics of the car - http://home.iprimus.com.au/dwitte/

I am interested particularly in diagrams/pics of the bellhousings. If the /6 box is the same (other than the convertor) internally as the smallblock item, then I can grab either one and go from there.

if anyone has diagrams or whatever, my email is dazmo2000@iprimus.com.au

Thanks again guys - you are a helpful bunch!

[nhdriver]

The small block 904's have a totally diferent bolt pattern(and starter location) than the slant 6 ones. What kind of gearbox did your hemi 6 have? What type of Auto trans did they come with origanally? Did they make a 904 for that engine?

[nasty VJ]

The Hemi 6 usually came with a Borg Warner 3 speed auto (which is only good for a stock motor)

Only Taxi pack Hemi 6's had a 904 torqueflite (which was the same as the smallblock 904) and those engine blocks are both rare and expensive.

Thats why I'm hoping for some sort of diagram of each.

I believe the adapter kit I have is for a small block 904, but I wish to confirm before buying a 'box.

[John Tozer]

Hey mate why go the 904 when you could go a 727?

The Hemi six was never fitted with the 904, however on the VG Valiant and in the taxi pack cars you mention, the Borg/Warner 35 was fitted with a 904 torque converter. The Borg/Warner 35 was never as smooth as the torqueflite but had arguably better ratios.

Now there were some 265 Hemis that left the factory with a 727s in the later VJ model, during the model run there was a strike at the Borg/Warner factory and Chrysler Australia had to cast some special blocks to accept the 727. I heard this a few years back and have recently found it to be true as an elderly gentleman who lives around the corner has a VJ Charger (lucky bugger also has a big block Jensen) with a factory fitted 727. I do no know why they chose the 727 over the 904 but they did, maybe it was a better combo.

Looking at your web site I see you want an E49 spec motor with triple Webers, this is not a good combo with an auto, especially with the cam profile. I don't think you should consider an auto unless your planning nitrous, turbo or supercharger. An E49 spec engine goes best with a manual but as you know a Borg/Warner single rail 4spd manual will not take to your planned 350HP very well. I suggest that you consider a Ford Top Loader or Borg/Warner super T5 manual instead as they would be way more suitable to your application.

I'm guessing here that you are considering an adaptor from the Castlemaine Rod Shop, did you see that they have a Hemi to GM turbo 350 adaptor, those guys make everything.

(before my US mates flame me, I must remind you all that torqueflites are getting thin on the ground in Australia and Mopar manuals are impossible to find)

Good luck with the Charger mate.

[Dart 65]

The 727 was a performance tranny, whereas the 904 was more of a passenger car version. But both can be hopped up to accept 350 horses, but the 727 will be a better place to start. I don't think my Aussie Mopar books have any diagrams to compare, but I will check and get back to you. I just received a copy of Scientific Publications Valiant Hemi, and it might have something like you need.

[nasty VJ]

Thanks John - I chose the 904 for a couple of reasons;

1. Easier to get hold of one
2. They absorb less horsepower
3. I already have the conversion kit

Also - the trans will be full manual valve bodied so a triple weber Hemi should be OK with it - i.e. no kickdown issues and so on.
The Cam choice will be close to e49 but better profile for the specific application of course.

The intention is that some drag race action will be planned for the car.

(Although I have been contacted by a local mopar nut that has a supercharged 265 in a Charger and boy does this thing look trick and apparently it goes like a rocket)

Also - the turbo 350 is not as great as many would think, nothing wrong with it but the general consensus across a lot of forums is that the 904 is tougher all round. (I do have a Mopar Action magazine somewhere with a /6 plymouth valiant pulling 11's using a stage 2 kitted 904 - and they leave it in drive while racing !!!!!)

Dart 65 - got any good tips on hop-ups for the 904?

[Dart 65]

I think Mopar Performance still makes a manual valve body and a shift kit for the 904. Both are easy to install and while they won't make the tranny bullet proof, they will help it handle as many as 350 +/- horses. What rear end gears are you running? How about the cam? What torque convertor stall are you planning to use? I will look for more specific info on the 904, as most of my experience is with 727s, and get back to you. By the way, I was also just on Mopar Market and left you a reply there too.

[nasty VJ]

Hi Dart,

rear end will be 3.23:1 or 3.5:1 (the charger is light - around 1000 kilograms) so this will be a good street/strip ratio for a 6 cyl.

I'm looking at a fairly lopey idle - probably will need a stall speed of 2000-2200 rpm.

The kit you speak of from MP was on the drawing board, I believe trans-go also make kits.

I have heard of some trick involving changing from 3 to 4 planetary gears or something (somewhat of a novice at this bit!).

And thanks for all the interest in my project - it's great that there are so many people out there who are willing to share their experience and enthusiasm.

[Dart 65]

You bet, mate. One of my dream Mopars is an E49 Charger R/T, Vitamin C in color with a black interior. A 265 Hemi Six Pack? Oh yeah.

[nhdriver]

The H.D. version of the 904 trans is known as a 999 They can take
all the power your hemi 6 can make. As they are probably quite rare down under, you can beef up a 904 to 999 specs. they have 4 unit planetery gear sets and a wider band and front drum which takes an extra clutch. 999's are being run in NHRA drag racing behind 426 max wedge cars(with adaptors) They dont last as long as a 727 but have less parasitic drag. Any number of the large performance transmission companies here in the states can set you up with the neccessary components. e-mail me if you nees some names(of the co's)

[nasty VJ]

Dart 65 - My Dreamcar too! (only I prefer the mercury silver version)

Good luck with the dream - the are super rare cars (only around 160 ever built) and the prices for a good one are rapidly rising, I have seen them advertised for as much as $75000 AUD lately.

nhdriver - I will be emailing for details soon - thanks for the offer!

It sounds like the conversion to the 999 internals is what I'm looking for (I don't wish to replace the transmission again!).

[Dart 65]

I bought a few die cast Aussie Chargers. I have both the Autoart E49s, the silver and the orange ones. Very cool.