904 in 65 Valiant Signet (US Dart)

65valiantsignet said

I am looking at getting a stall converter for my 65 Valiant Signet that has a 904 in it. It is the lovely ball and trunnion one... Anyways, when I was speaking to Mancini Racing they asked if it is 19 or 24 input spline. Any thoughts as to what it is and as well suggestions to up the stall from factory? The engine was replaced with a 1969 318 with a mild 340 cam. I have no idea of what the cam is...

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904 transmission from Late 1962 till 1967 had 18 splines, and in 1968 went to 27 splines.
19 spline and 24 spline on the input shaft --- a 727, not a 904, I'm surprised at Mancini giving you the wrong information.
It will be tough for anyone to suggest what converter you will need FOR YOUR APPLICATION, as the information you've given is minimal. For you to get the correct converter stall a converter builder will require: Cam specs, diff ratio, rear tire size, etc. From what you've mentioned, a factory 11" converter built for you with the right weighting and spline count is probably all you will need. With the spline count of the 904 and the weighting of it for the 340, any converter you get will have to be custom built for you. If you want a high stall spec sheet we used at my pre-retirement employer, send me a pm along with your home email and I'll be happy to send it to you.
A poorly applied high stall in any vehicle is a waste of time and money. DO IT RIGHT ONCE.