flathead turning over

I am woking on an Av8 with a 40 motor and still 6Volt. Motor is rebuilt and not started yet, turns over with a 1/2 drive ratchet, but the starter doesn't seem to want to turn it, new battery and rebuilt starter, should the 6volt battery start a fresh motor or should I give it a 12v boost or perhaps a push/ tow start . any ideas?? thanks

 

check grounds.. also make sure there is no paint on the oil pan where the starter is mated.. the starter also..

 

Most 6 volt cranking problems come down to two things. 1 battery with not enought amps to do the job even if it is new. 2 excessive resistance in the cables due to too small a cable or bad connections. Idealy 2 -O cables and the ground connected as near the starter as posiable. Starter also may need attention,bushings -brushes.
But I have used 12V jumps on 6V new engines for the first starts more than once. But give the cables/connections a good look over. And as far as that goes put the battery on the charger to get it to fully charged.

 

All covered here already! Rebuilt engines are clusters of ground problems (all that paint, all that gasket goo), and unless you know what you are doing and are a good hunter, your cables are surely tiny gauge 12 volters...

 

I was using jumper cables to first start the engine and had the same problem. Used good bolt on cables and started right up. Just a thought.

 

Reminds me of when I once jump started a 6 V battery with a 12 V battery and the
6 V battery literally blew its top. BE CAREFUL.

 

When jumping 12 to 6 volt connect the ground jumper cable to the 6 volt car last and not directly to the battery. The 6 V battery will be putting out gas and you WILL get a spark if you hook both cables from the 12 V batt to the 6 V batt. Make your ground hook up to a good clean place on the engine ,this is a good idea on regular 12 V jumps also.

 

update - made up cables using 1 gauge and cleaned paint off where starter mounts and it works very well. thanks for the input.

 

ALL old cars have bad grounds everywhere, the clunkers from rust and dirt, the restored ones from thick paint and gasket goo. "If it don't go, ground it..."