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pg 220 of the factory manual(avail on the tech page of http://www.olddatsuns.com) only shows the battery ground cable going to the alternator body. That would be stock.


Running the ground to the block helps with the return side from the starter, which carries more current than all the other systems combined. Grounding the head helps with the return circuit from the spark plugs. I highly recommend running a ground from the eng to the body. The only stock ground between the two that I know of is a 10ga wire between the bellhousing(near starter) to the frame. Since all the lights/wipers/radio/wiper...all ground to the body, an additional ground from the bat to the body is a good idea. You can either run it from the eng to the body, or directly from the bat.


Anyone wanting the strongest ignition should run a dedicated ground to the distributor body....points or EI.

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Mike's right on this. I had a catastrophic short from the POS to the body. The only path to the engine block was down the throttle cable... which got HOT! the plastic melted and hardened around it. No throttle at 1:30 in the morning with 15 miles to get home.


On some 720s the NEG cable has a lug on it about a foot from the battery that bolts to the inner sheet metal fender then on to the intake manifold.

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yeah that owners manual was a guess. i love to stroll through the 521 service manual just to look at the pics. on that diagram it does show the ground cable going to the alt but i cant tell that it's connected to the top or bottom mount. maybe i'll stroll through the book some more and try to find an actual pic.. best book to have if you have a 521.

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