Check the voltage at the coil while you're cranking. I'll bet it's going to be low. When we get obsessive-compulsive about getting good voltage to the starter with big cables, etc. we often forget that other circuits can suffer from the same loose, dirty and high resistance connections as the starter. Make sure the connections from the ammeter to the ignition switch and from the switch to the coil are in good shape. Are the points clean and gapped properly?
Once all that is in good shape you probably won't need to add any gas to the carb, but if you do only use an ounce or two. With as low compression as a stovebolt engine has, a quick spritz of starting fluid won't hurt- - - -just don't overdo it. The Cummins Big Cam 400 engine start in northern California that I witnessed is a good example. After squirting 1 1/2 cans of ether into it, the nose-pickers from the truck stop tire shop figured out the batteries were low. A quick boost from an 8-D battery in a coaster wagon got it cranked- - - -and it scattered engine parts all over the lot!
Jerry
