Will my original 66' 273 904 tranny work my my 69' 340?

[daves66valiant]

I have a 66' Valiant with the original 273 engine. It has the 904 tranny with column shift. The trans needs to be rebuilt and probably beefed up for the rebuilt 69' 340 I have to replace the 273 with. Will this tranny just bolt right on with the existing bellhousing from the 273? Are there many other fitting issues to worry about? I will have a new driveshaft made for the 8 3/4 swap. A loop will be made too.

Separate question. What can I do to this 904 tranny to beef it up enough for the >400hp 340? BTW the car will primarily see street use.

thanks

 

[Jim Lusk]

Yes, the trans will bolt up and work fine. I can't advise you in regards to mods to it to last behind the 340, though.

 

[Charrlie_S]

You will need an adapter "ring" to go in the end of the crankshaft, to support the torque converter. The 340 has a larger bore in the crank then the 273. You can have it made locally, purchase it from Wildcat motors, or Pat Blaise transmissions. Why not use a LA-999 trans. These have the "beef" you want, and will bolt right up. Only problem is your speedo hookup (speedo shop can make the correct cable), and the torque converter. Most LA-999's were used with 360 engines and had "out of balence" converters. A 69 340 uses an "neutrel" balence converter. Just remove the weights from the converter.

 

[Mark Nixon]

1966 904s use the same speedo adaptor assembly as the later years.
A 998/999 tranny is only 1 clutch, and maybe a heavier band, stronger than a 904 in typical applications.

As far as the convertor hub goes, since you are rebuilding the tranny, update to the later ('67-'77 pre lock-up) pump drive and front pump assembly, then you can run a whole variety of convertors, without having a "one off" set-up that'll probably come back to bite you later.

A lot of slant six 904 tranny parts interchange with the V-8 904.

Mark.

 

[Charrlie_S]

1966 904s use the same speedo adaptor assembly as the later years.

that is correct. I was misremembering. A 66 cable is use to install the late trans in the 65 down cars.

A 998/999 tranny is only 1 clutch, and maybe a heavier band, stronger than a 904 in typical applications.

I think it is one additional clutch disc and plate, in both the front and rear clutch. This amounts to a 25 % greater torque capacity. Also a double wrap rear band. The 998 case is different to accomadate this band. The 998 front pump and clutch drums can be installed into the early 904 case.[/qoute]

As far as the convertor hub goes, since you are rebuilding the tranny, update to the later ('67-'77 pre lock-up) pump drive and front pump assembly, then you can run a whole variety of convertors, without having a "one off" set-up that'll probably come back to bite you later.

not a "one of" converter. can run any 68 later 904-998-999 converter, just needs to be neutral balance. Aslant six or 273, or 318 or early 340 are all neutral balance converters. But if you need to rebuild the tranny anyway, and you wanrt to upgrade the internals, the parts have to come from the later trans, anyway. Why not just use the later trans.[/quote]

A lot of slant six 904 tranny parts interchange with the V-8 904.

Mark.[/QUOTE]
There are many ways to reach your goals. I thing it is just easier to use the later trans with the later engine.

PS: I run a 65 A-904G (slant six) with a 64 valve body (to use the push button shifter) with the 998/999 front pump and clutch drums. I need to use a special built converter, because of the early crank with the small pilot, and the large input shaft.