starter or Ignition trouble

[Mrcustom]

I just finished hooking everything up in my 57 pickup brand new crate 350 motor, brand new TH 350 Transmission, Radiator, well you get my point. So I start it up sounds great 75 lb oil pressure 14.7 amps 175º .Sounds good now the problem is if I turn the key to off quick all the way it sounds like the starter is engaging but if I only turn the key half way off, I guess it would be the Accessory. The motor shuts off fine no problem.Very annoying and it kinds of scares you when you don't expect it. Any Ideas? O yea with the old 400 that was in there I didn't have this problem. I did though have the problem where I had to let go of key to get it to start. Hope you can understand my babbling.

Jim

[55Cameo]

Sounds like its in the ignition wiring or the switch itself. Have you checked those hook up's yet?

[OrrieG]

Original starter switch or new? I have had shorts where the start circuit would not work, but it would try and fire when I released it and it jumped back to run. Sounds like a switch issue, usually not repairable.

[Mrcustom]

The starter is a brand new high torque and the switch itself I believe It came with truck. Does anyone know where I can get a good pic of Ignition switch wiring. I really don't know how to check if an ignition switch is bad, does anyone know this. Thanks

[mr48chev]

stock switch, universal switch or one on the column in a late model column?

If it is under the dash check for wires crossing each other and making contact where they shouldn't.