Quick run down, the slant six in my 71 dart is giving me fits, the car starts right up with jumper cables on it but without will not turn over at all, no clicking nothing, replaced the battery, alternator checked out good, replaced the voltage regulator, the starter will not turn over when i bridge the terminals with a screw driver but sparks, starting to get very annoyed thanks in advance

 

Sounds to me like you have a bad battery clamp

Do some troubleshooting

1 You need three hands or a helper. Stab your meter probes directly onto the two battery posts, and short the relay. You should read NO LESS than 10.5V. Less means the battery is dead or defective

2 Put one voltmeter probe on the + battery post, and the other probe onto the clamp on that post, and short the relay. You should read very little, a tenth or two of a volt

3 Do the same thing, - post and clamp

4. Put a voltmeter on the block, and stab the other probe directly onto the battery CLAMP on the batter, short the relay. You should read VERY little voltage. If you read battery voltage or more than one or two tenths of a volt, the cable or connection is bad

5 Do same thing, + cable, one probe on starter relay stud, other probe on the battery + clamp. Same as 4 for readings

6 One meter probe on starter big post, other probe on starter relay post. Same readings as 4