I bought a 57 Chevy 150 that has been completely mismatched, no original parts, so it’s hard to find correct guides. But I had brought th starter Down to auto shop to test after I couldn’t get it to start and it was fine and after putting it back in and hooked everything up it still won’t get enough power to the starter to turn it, I’ve tried using the remote starter switch button connecting a clamp to positive battery and “s” terminal on solenoid and have the main post from battery to solenoid hooked up to bypass in case it was a wiring issue but when hitting the switch the starter just makes a clicking noise like it extends but doesn’t have enough power to do anything else. But the starter itself should be good since it was tested and I got a new solenoid anyways so it should be good also battery’s been charged and tested, but even with all wires hooked up correctly starter just clicks
Check your grounds and battery cables. Also if the starter was tested with no load that's not a definitive test. If it does not crank with power connected directly to the motor itself, bypassing the solenoid, either the engine is seizing up, the battery is bad, or the starter is actually bad despite the test. Can you turn the engine over by hand? (Is it even the original engine? Unlike modern cars, major components like engines and transmissions can be easily mixed and matched in those old buggies.)
Looking at the starter motor image on rockauto.com, it looks like there is a strap going from the solenoid directly into the starter motor. Try bypassing the solenoid by bridging the solenoid contacts, or connect the starter motor to the battery directly using a set of known good jumper cables. (Six-cylinder starter shown since the 150 was the economy model for '57 - you did not state engine type - but any GM starter from 1950s through at least 1980s should have similar construction.)
