904 Beef Up

Tech Question


Richie Henzie, Kelowna, BC, Canada, 1969 Dodge Dart 318

I have a 1969 Dodge Dart with a 318 and a 904 auto trans. The car is in very good shape and I want to find a 340 for it. My question is can you beef up a 904 to make it handle lots of HP – say, 375 hp? Thanks


Rich, it is very easy to build up a 904 to handle almost any HP level. The 900+ HP Super Stockers use 904 internals in a 727 case (because they are light and small diameter, the car goes quicker.)

So now it comes down to $$$. To build a beefy 904 requires good parts – better steel, etc – because the parts are smaller. As the HP level increases, we start talking about almost 100% aftermarket / custom internals – even shafts, drums, etc. For this reason, for street-driven cars, the ol’ standby 727 is genearlly a better plan, and more relaible in the long run.

However, for a car that will not see many street miles, i.e., primarily a track car, the 904 is the quicker bet. At your HP level, it would not be a major undertaking.


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