Transmission Advice Needed

[rugbyjon112]

I recently discovered that my original 318 in my ‘69 Fury III has a severely cracked block from improper winter storage by the previous owner. I have sourced an early ‘70s 360 that I’m going to put in it. My Fury currently has a 904 transmission in it but I have a good 727 transmission from a 383 big block that I’d like to use instead. My question is, what do I need to swap besides the flexplate and probably the driveshaft?

 

[Welder guy]

The 360 is a small block engine. The 383 is a big block engine. The 383 727 transmission will not bolt on to the 360.

 

[MONC440]

The 360 is a small block engine. The 383 is a big block engine. The 383 727 transmission will not bolt on to the 360.

That is correct. Also that 904 can be built to handle the 360, no problem. It will actually be better than the 727 because it has a less rotating mass that means more power. If you want help with a proper rebuild, let me know.

 

[CBODY67]

Yes, the beefed 904 was actually preferred as far back as 1968 over the 727 for its lesser power consumption. There is also a 2.75 (approx) factory low gear planetary that has 4 pinions in it, too. Unfortunately, that bit of added torque multiplication makes a marginal difference in real world performance. More difference in the numbers than in "analog accelerometer" feel, to me.

Seems like the 360 torque converter needs some balance weights on it?

Just some thoughts,
CBODY67

 

[MONC440]

Yes, the beefed 904 was actually preferred as far back as 1968 over the 727 for its lesser power consumption. There is also a 2.75 (approx) factory low gear planetary that has 4 pinions in it, too. Unfortunately, that bit of added torque multiplication makes a marginal difference in real world performance. More difference in the numbers than in "analog accelerometer" feel, to me.

Seems like the 360 torque converter needs some balance weights on it?

Just some thoughts,
CBODY67

Yes I do have a low gear assembly for a 904 if you want to go that route. It will give you a a better off idle acceleration. It was what Chrysler did before going to the OD transmissions when they were putting 2.xx gears in the bigger cars in the 80's. The engines were not putting out the HP and TQ of the cars in the 60's and early 70's so the gear reduction helped a bit. First gear would be 2.77 vs 2.45, second would be 1.55 vs 1.45 and third is still 1:1. It would give you about a 22% gear reduction in first so a car with a 2.92 rear gear would act like a car with a 3.55 gear.

 

[wyrmrider]

727 is more durable why they used it behind 6 cylinder taxis small block 727 cases are easy to find and you can swap your guts
or find a 518 from a 92-94 truck'
all good choices depending on use

 

[CBODY67]

There is NO doubt about the 727 having more torque capacity and related durability than an OEM 904. Just like GM using a THM400 in similar HD uses with lower-powered engines attached to it.

In the particular 1968-era issue of HOT ROD magazine which detailed how to upgrade an OEM 904 to handle more torque that noted that not many trips down the drag strip with a 904 318 2bbl before it would need to be rebuilt. Of course, "Aftermarket to the rescue!" In this case, B&M, with upgraded frictions to do the trick. It was ALSO noted that a 727 was not needed in all situations, just the upgraded frictions! That an enhanced 904 could stand up to a reasonably-stock 340 being drag raced, which would be faster than if it had a 727 behind it as the 904-family took fewer horsepower to run.

Same situation with the Turbo Buicks and their THM200-family automatics. Considering that some earlier THM200s (designed for 4-cyl and V-6 cars of 150 rated horsepower) were known to grenade right off the transport trucks, BUT with better frictions and a few tweaks, could stand up to much higher outputs, by observation.

Enjoy!
CBODY67

 

[michiganhotrod1]

The 318 is internally balanced. The 360 is external, and the torque converter weights are different. The Mopar Performance engine manuals have a discussion on this, and i believe Mancini Racing still sells a weight set to make a conversion.
Mark

 

[MONC440]

The 318 is internally balanced. The 360 is external, and the torque converter weights are different. The Mopar Performance engine manuals have a discussion on this, and i believe Mancini Racing still sells a weight set to make a conversion.
Mark

You are correct. In my opinion if you don't have a 360 torque converter with the big weight welded to it is to buy the special 360 flex plate. I know the OP referred to a 360 just wanted to note a 360 LA and the 5.9 magnum are different so make sure you get the correct one for your application.