Why not get one off a car at a PnP?

Barring that, what even you worked up failed at one connector or the other with the engine side being the most likely, right? The main reasons a wire with eyelet ends would fail in this application are poor crimps and/or lack of strain relief.

Assuming you do not have the proper tool to do a high quality crimp, just buy a 12 gauge wire with eyes on both ends...most parts stores will have them over near the batteries and battery clamp. Get something at least 3" longer than the old braid.

Now, before installing it add the smallest heat shrink tubing that will fit over the eye for both ends. Shrink it then add another layer for the same size heat shrink but do not heat that up. Install both ens of the wire on the car but create a loop int he wire before installing the second end. Once you have everything positioned the way you want it, heat the second layer of heat shrink tubing.

This is a virtually failure proof method to make up a wire in a vibration prone environment. The loop keep the connector ends from taking the full brunt of the vibratory load and the heat shrink adds strain protection.