360 Starter Problems
On the front of your torque convertor, there is a nub or "nose".
It rests in, and is supported by, a recess machined into the rear of your crankshaft flange.
The issue is that in 1968, the diameter of the convertor "nose", and therefore the size of the pocket machined into the crank flange, was increased.
This means that when a post '68 engine is mated to a '67 or earlier 904, the nose of the convertor is no longer rigidly supported by the crankshaft because of the differing diameters. This can cause all sorts of unusual vibrations that can result in a cracked flexpate or ultimately a trashed front pump as @Oldmanmopar mentioned. And no, a later torque convertor cannot be used on a '67 and earlier 904 because of input shaft differences in diameter and spline count.
The solution? A bushing seated into the later model crank flange to make up the difference in diameter, which will now properly support the nose of the early torque convertor.
Here is one source:
Chrysler Torque Converter Flexplate/Crankshaft Adapter | 1.81" OD x 1.55" ID | A904, A727 | OE | 1 Year
Welcome to the Wonderful World of Mopars.
Our motto is "It's always something. Why the Heck did they do that?"
Here's the short and sweet explanation:
On the front of your torque convertor, there is a nub or "nose".
It rests in, and is supported by, a recess machined into the rear of your crankshaft flange.
The issue is that in 1968, the diameter of the convertor "nose", and therefore the size of the pocket machined into the crank flange, was increased.
This means that when a post '68 engine is mated to a '67 or earlier 904, the nose of the convertor is no longer rigidly supported by the crankshaft because of the differing diameters. This can cause all sorts of unusual vibrations that can result in a cracked flexpate or ultimately a trashed front pump as @Oldmanmopar mentioned. And no, a later torque convertor cannot be used on a '67 and earlier 904 because of input shaft differences in diameter and spline count.
The solution? A bushing seated into the later model crank flange to make up the difference in diameter, which will now properly support the nose of the early torque convertor.
Here is one source:
Chrysler Torque Converter Flexplate/Crankshaft Adapter | 1.81" OD x 1.55" ID | A904, A727 | OE | 1 Year
Welcome to the Wonderful World of Mopars.
Our motto is "It's always something. Why the Heck did they do that?"