Need Opinions on Starting Problem

My 88 Formula 350 won't start. For a few weeks it was cranking slowly but starting after holding the ignition on for a few seconds (it would slowly speed up the cranking the longer I held it on). So I let it sit for about a week, went to start it up and it cranked once and then nothing. Next obvious thought was the battery is dead, so I gave it a jump, and it cranked fast but wouldn't fire at all. I checked the voltage with the jump on there and it was around 13 volts, idk if that matters or if just the amperage matters when starting. I don't know if it's the starter because the way it would slowly speed up the cranking as I held the ignition, or if it's just a bad battery. Can anyone pinpoint it?

My guess would be the starter, especially if it was previously cranking slowly. Mine does that sometimes, but eventually starts. *knocks on wood*

I'd check the battery and alternator first to see that the voltage is holding steady since it cranked fine with a jump. Remember to charge the battery before you test it. There is a possibility of the starter being bad, but normally those starters do not ehgage when they go bad, but there is always the exception. My guess for starters is a weak battery or a drain in the alternator.Once you rule them out, then you can look elsewhere. Remember if the computer doesn't have enough voltage to operate, the car won't run.

Hmm...well shouldn't it have started up when it was cranking at the right speed? That's the only confusion in my mind, I can understand it not running w/o enough voltage but it should've run as long as I had the cables on there, right?

Is there any clicking when your attempting to start the car?

Clicking as in starter solenoid clicking, or some other type of clicking?

Either way, no I don't hear any clicking, just the whirring of the motor turning over.

Did you check the condition and location of the starter gear?. They sometimes become jammed on a chipped/damaged flywheel tooth. Or just become lodged. I would also try a lite tapping on the starter with a hammer.Alot of times if it is a jamming condition that can free up a gear. Good luck to ya.

PS- yes that was in relation to the solenoid.