@Dcfirebottle,
Okay! I read that you took the old factory starter off and put on a "high torque" type. I'm going to assume you mean the mini starter, right?
I consider myself some what of a semi-expert in this because I went through four flexplates before I discovered what my problems were, and I had no help, I had to figure it all out myself. It narrows down to three main problems.
1)
flexplate It's possible the mounting block on your new mini starter is for a 12" 153 tooth flexplate. That's probably why you never could get it shimmed, and you never will! When you ordered the starter did you know what flexplate you had on the 305? It could be a car flexplate which in that case it is a 153 tooth flexplate. Most truck engines will have one size or the other flexplate, but I have an TH350 auto in mine and it has a 168 tooth 14" flexplate and most trucks do.
2)
Mounting block If you have the 168 tooth flexplate on your truck then your starter is okay, you will need to change out the mounting block to one for a mounting block for the 168 tooth fexplate. Otherwise you'll never seem to get the shims right. It'll be to few or to many. The task will come in where you'll have to take the mounting block off the starter and change it out with the block for the bigger flexplate. Or just go get another mini starter and make sure it's for a 168 tooth flexplate. Then it should fit.
See, back when I was putting one on my truck there was a third bolt behind the solenoid, there are three bolts on the mounting block and all the mini starters were made that way and I went through several kinds. Nowadays the third bolt is outside of the solenoid and it's easy to change out the block. I guess the makers must have learned their lesson. that you had to take out to remove the block. then put that third bolt back in and remount the solenoid. It was a super pain in the rear end.
3)
bolts Also, make sure you are using "starter bolts"!! Not 3/8" bolts. You will have endless starter problems with getting the starter to stay put if you are using 3/8" bolts. Stater bolts have serrations near the end of the shaft of the bolt where the threads start, like about an inch or a little more of serrations around the shaft of the bolt. What these serrations do is they take up the slack where the mounting block of the starter and the engine meet up. Now, there is instructions that will say to make sure you're in the correct mounting holes in the block, but I can guarantee you if you had put the starter in the wrong ones it would be at an impossible angle to the flexplate. You'd know if it wasn't in the right holes.
The wiring should be the battery wire, a sensor wire maybe #14 orange or tan, a #12 purple wire coming from the ignition switch, and a #14 yellow wire that's also part of the ignition wiring. The instructions will point to the correct hook up of the wires.
If all these things are like I have diagramed here you should have a good experience with your new mini starter. And yes, it will end all your starting problems. It certainly hqas mine. Once I relaized I had regular 3/8" bolts in mine that alone solved a lot of problems I was having. The eaten up flexplate teeth was due to 1) the bolts, and 2) getting the gear spacing correct with the proper thickness shims. Usually (1) .020" shim should get it. If you need to get a little closer you can use a .016" shim.
I hope this helps. Good luck! And if you need to know how to get the flexplate off without pulling the engine let me know here and I'll tell you. See, I didn't have a hoist either and had to figure out how to remove it safely from underneath without to much trouble at all.
