73 400 pontiac problem

[ddman]

I bought a 73 400 pontiac a few weeks ago. The man showed me a video of it running bout a year ago. I put the engine on a stand so I could change freeze plugs do some cleaning and maybe paint it. It turns over good by using a breaker bar on the crank bolt. Hooke jumper cables to it poured a little in the carb cranked it and it fired up for just a second or two. Filled carb bowl this time and tried to crank and barely would turn over. I pulled plugs out hooked up cables and it spins over great. Put two plugs in, one each side it won’t turn over hardly at all. Moved plugs to other cylinders same thing. So I bought a new starter today, made no difference. Starter is shimmed out so it’s not binding up the starter. I pulled valve covers off and all the valves move when cranking over with plugs in it. It getting oil thru the push rods so I know it’s building pressure. I’m out of ideas, hopeing maybe someone has seen this before. I did pull exhaust manifolds on both sides thinking maybe they were stopped up, no change. Y’all got any ideas? Thanks in advance.

[FormTA]

How do you have it hooked to the battery? Sounlike bad connections or too small of wire.

[ddman]

Jumper cables run from truck, red on big terminal on soliniod, grounded to plate on back of starter, then screw driver to jump from small terminal to big terminal

[5th T/A]

Not saying this is the same as your problem, but it could be.

A few years ago I had a problem with the stater on my Harley Ultra limited. This bike requires a pretty hefty battery for good cranking speed. At first I thought it was just a worn down battery. I tried using my jump pack and it didn’t have enough power. So then I used my 45 year old jumper cables and a known good car battery, still not enough torque to turn the engine over with the plugs installed. I just about figured I had a bad stater when I felt a very hot spot on one of the jumper cable alligator clips. Corrosion on the clamp was keeping it from providing enough current. So the original problem was a bad battery. My Jump start battery pack didn’t  enough current and my jumpers cables couldn’t carry enough current, all leading me into misdiagnose the real problem.

[tinpusher]

I’m thinking the same as above, wire connections to the starter, the starter itself, what is the timing set at? Too far advance will cause cranking issues.

[ddman]

I don’t have power to the distributeright now, just trying to get it to crank over. I’ll put battery cables and take the battery off my truck tomarrow, that will eliminate bad jumper cables.

[ddman]

Put battery cables on starter and for the ground. Turns over just fine, ran jumper to Bart side of distributed poured some gas in carb fill bowl shorted soloniod and it fired right up. No exhaust so it was loud but no knocks.