If you don't have a ground cable between the block and frame, or directly from the block to the battery ground post, you likely have a high resistance ground path that drops voltage that the starter needs. The stock setup has both battery to frame and frame to block ground cables (see pic). You need a ground path of appropriate size all the way from the block to the battery. You also need to be sure there's no paint at the bolted connections.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
