727 W/ 904 internals
 

Is anybody running 904 internals in a 727?, I would like to try this combo but need some info on it first

Re: 727 W/ 904 internals
 

Pro- Trans, in CA , Dave Smith, 661-940-7400

Re: 727 W/ 904 internals
 

Why not just run the 904 ?

Re: 727 W/ 904 internals
 

In our big block stockers it would be impossible to be competitive

without a Pro trans 727 with 904 internals. My kids Roadrunner picked

up well over a .10 over our aluminum equipped low gear 727 by Pro trans.

That is the difference between first round loser and Class Winner a couple weeks

ago at Sport Nationals. Both hold up real well as long as you change trans oil

regularly. Until NHRA allows an adapter for big blocks to be legal you

need a 727 with 904 guts to be competitive.

Re: 727 W/ 904 internals
 

The 904 has a different bolt pattern than the 727, they're not interchangeable.

JimR

Re: 727 W/ 904 internals
 

727 come in both small block and big block bolt patterns.......easiest way to ID
on shelf is small block is above starter the block bolt hole and starter bolt hole are directly above each other and big block starter hole is at 45 degree angle
from block bolt. Also if you measure two top bell housing holes there is a inch and a quarter width difference between big and small blocks. 904 is physically
much smaller and quite a bit shorter as well as imput shaft is smaller. There are currently available adaptor housings to mate a big block to a 904 and that
is what I use on my Bracket Cars. I do not believe that they are accepted for
stock or SS and I wish they were as it would save mucho money.

This should be way more information than anybody probably wanted......Sorry

Re: 727 W/ 904 internals
 

Chrysler made 727s for both big blocks and small blocks but built 904s for small blocks only, and I think Mark runs a big block.

Re: 727 W/ 904 internals
 

Yeah, were running a 383 W/ a light weight 727 a really super trick piece by Automatic Performance Transmissions. I dont think I could get a tenth with a 904 but would still try it, I would like to build the unit myself but it was still unclear if the whole geartrain is used or just a few components. My bracket car did'nt go faster with a 904 but it did pick up MPH.

Re: 727 W/ 904 internals
 

Not at all John! Love those details. Good to hear those positive results. I'm investing in a 727/904 currently being built!
MWNorris

Re: 727 W/ 904 internals
 

Where do you get an adapter John?

Re: 727 W/ 904 internals
 

If I may........J. W. Transmissions in Rockledge, FL makes the "Ultrabell" as one option. It's basically an SFI certified flywheel shield as well as an adapter available in quite a few configurations.
I couldn't help but wonder if NHRA could be petitioned for its acceptance in Stock and/or SS based on its safety qualities, as long as a corporate trans is used. (If it hasn't been tried already.) GM and Ford appear to have the luxury of interchangability of their big and small transmissions between big & small blocks. It would save some money over 727 cases with 904 internals.

Re: 727 W/ 904 internals
 

Been there done that!!!!!!!!!!! First asked div. passed me on to national both said not yet ...wanted to use 904 with ultra bell for stock in my big block combo,, I do think if more people would call and ask it would help,, it would be a safety issue also the ultra bell is sfi approved..bryan d stk5010

Re: 727 W/ 904 internals
 

The rules regarding the case being OEM would have to be changed I dont think that should happen in stock, maybe Superstock.

Re: 727 W/ 904 internals
 

When we bought the White 73 Roadrunner 6 or 7 years ago it

had the 904 with adapter mating it to the 440. It had been raced

for several years in stock with it and apparently never had a problem.

I did not ask anyone or say anything about it ................ I just removed it!

Phillip: I will go over to shop tomorrow and let you know

who manufactured the unit. It has the trans bell housing machined

off and replaced with a bolt on bell housing with big bolt pattern

adapter and requires no spacers or special flexplate but uses

904 converter of course.

Re: 727 W/ 904 internals
 

Oh, I was thinking something more like a midplate adapter.
Why is that the fords and chevys get to use the small transmissions and we have to go thru so much hassle?

John, I need a converter for the 340. pm me if you have anything good for sale. My faithful old Dynamic came apart last weekend at Ashcroft.

Re: 727 W/ 904 internals
 

Its a bolt pattern change thats not legal.

Re: 727 W/ 904 internals
 

Bob,
On another thread someone stated that the FE bellhousing's have to be cut and welded to make a c4 work, Is this true?

Re: 727 W/ 904 internals
 

Havent got there yet, if so then a pro trans C6 - 904 is in order, Alex D could answer that for sure and I saw another c-4 post that I will have to go read but the chevys have it made.

Re: 727 W/ 904 internals
 

Phillip, From what I just read you need an adapter for a c4 to FE, there is a sheild bolt on that works but than thats a gray area.

Re: 727 W/ 904 internals
 

Well I guess it's like the pontiac guy's running the chevy bolt pattern transmissions, A little gringing and drilling is o.k with nhra. I guess if I weld a 727 bellhousing to a 904 case all will be fine. Time to fire up the spool gun

Re: 727 W/ 904 internals
 

Phillip, can you give us a specific example of this?
I can't see the need for such a thing.

Re: 727 W/ 904 internals
 

NHRA allows a an adapter for the FE to c4

Re: 727 W/ 904 internals
 

Lighter torque converter also, how do you petition for something like that?

Re: 727 W/ 904 internals
 

You send an email to the NHRA tech guy's. List the reason for the request and and a few example's of others that are doing what you. Then you get enhanced.

Re: 727 W/ 904 internals
 

Which point Mark? If it is the pontiac/chev trans you need look no further than a certian Firebird. They were protested a few years ago ( At Fallon I believe) and NHRA wouldn't do anything about it. Am I mistaken?.............

Re: 727 W/ 904 internals
 

Any GM trans worth a crap was made in Chevy and BOP configuration ,or both.
There was even a BOP Powerglide case .
The Chevy pattern 904 mail truck trans isn't legal in S/SS, but still it bolts right up.
The 700R4 o/d is Chevy only, but nobody uses that.
I just don't know what issue you're talking about.
PM me if you want to.

Re: 727 W/ 904 internals
 

Mark,
The Chevy pattern Mail Truck 904 "is" legal in certain SS classes.

Re: 727 W/ 904 internals
 

Mark,
It's a fact that they were using a modified chevy case, Why? I don't know and don't really care. I don't have to run them heads up so it doesn't concern me.
What does concern me is that GM and Ford racers get to do something Mopar racers aren't allowed to do. The JW bellhousing to bolt a 904 to a big block costs about $400, A protrans is $4000-$5000. It doesn't make sense.
How many GM racers have had to throw away a repairable case because of a cracked bellhousing? This would be a good fix for them also. If NHRA is going to let the Ford racers use an adapter then we all should get that option. Right?

Re: 727 W/ 904 internals
 

I just sent an email to NHRA requesting we be allowed to use an adapter, If enough of us do this we may get somewhere.

Re: 727 W/ 904 internals
 

Just the hood scoop cars, right?

Re: 727 W/ 904 internals
 

PM me with the details... I'll investigate it.

Yes , I agree . Everybody gets an Ultra Bell...or nobody!

Re: 727 W/ 904 internals
 

I have also seem many GM automatics that had both the Chevy and the "BOP" bellhousing patterns.

Re: 727 W/ 904 internals
 

Phil,
Like Mark said I have no idea why a Pontiac guy would do this. For the amount of work it would take it would be easier to stuff the guts of the transmission into a BOP case.
All the same trans used in performance applications the Turbo 400, 350, metric 200 and PG were all available with a BOP case and there are lots of cores out there. And as Rory said there is also the dual pattern cases.

Re: 727 W/ 904 internals
 

Maybe the chev case is stronger than the BOP?
Anyway's I wasn't trying to pick on the guy's that did it, Just knew that it had been done and that it was protested and NHRA did nothing about it.

Now back to the subject,
Mark, Can I bolt a 727 tailshaft to a 904? I don't want to build a new driveshaft, LOL

Re: 727 W/ 904 internals
 

Don't know that one .I'm a GM guy, and an occasional C4.
I'm sure someone here can tell you more...Maybe Alan?

Re: 727 W/ 904 internals
 

Phillip: I Do not believe that it would be very possible or economical to exchange Tailshafts......................................
Trans output shaft are different in length and diameter as I recall andmaking
a output shaft would be a small fortune. Both tail shaft have rear mount in same place and take same transmission cross member . The yolk is twice
the size on front of drive shaft on 727 than on 904. Nevertheless , it would
much easier to make a new drive shaft or rework a stock one than modify
the transmission!
I am sure that there are some transmission builders than can give you
better advise than I can.................I have not rebuilt my transmission since
the 80's. More effective to just cut a check to Pro Trans and cheaper
in the long run with my skills.
Phillip: Will answer your E mail tomorrow.

Re: 727 W/ 904 internals
 

I think this was the Cadillac automatics. I have seen one in person.

Re: 727 W/ 904 internals
 

Phil,
send me the info I'll send a request also

Re: 727 W/ 904 internals
 

I don`t know Jeff. I`ve seen the multi pattern Turbo 350`s & 400`s in a number of none Caddilacs. Not sure what the reason was, other than maybe streamlining inventory?

Re: 727 W/ 904 internals
 

Never tried that, I don't have the parts here to compare, but I doubt it.

Like Mark, I do a lot more GM stuff than anything else, I can do all sorts of tricks with GM stuff, from PowerGlides to the latest stuff. The Ford and Chrysler stuff I can build really nice race transmissions with, but "trick interchanges" are out of my league.