so i went to start my 71 cutlass supreme with 7.5 ltr it turnd over once and then everything went dark (ligjts all went out ) so it had been a few weeks since i started it so thought it was a dead batt even tho i just bought a new one the month before charged the batt and same thing happend interior lights come on and off as they wish i changed starter and when to start it and did the samething it did initially the positive battery cable is new I know it seems like a short somewhere not too sure

 

Sounds more like an open / high resistance connection than a short to me. I had similar issues over the years due to corroded or loose connections on the battery cables. The poor connection allows some current to flow initially, then goes open since it can't support the amount of current trying to flow. Clean the battery terminals, especially if you have repair ends - make sure the part where the cable is clamped is clean and tight, same thing with the battery post terminals. It could also be the starter itself, either the high current contact or the armature windings. The contact disc can get arc spots that don't conduct, so you can remove the disc and turn it over and use the "good" side. If it's the armature windings, a rebuild or new starter is needed.

 

I have ran into this on old tractors. FUN 71 has the right idea, a **** poor ground connection/corrosion would be my guess.

Pat

 

Welcome to the site, X3, check battery cable connections.

 

Side posts with the cable sticking out to the left (relative to the battery's side) can loosen when not overly tight due to gravity. Sometimes a tug works.