454 not starting
 

Picked up an 87 suburban last Friday, been running and driving just fine til today. Has a carbed 454, had a brand new starter put in before I bought it, just did plugs and wires yesterday, ran great. Went out today, hopped back in to leave, wouldn't start. Acting like it didn't have enough power, put a new battery in, same problem. Gets about half a crank, sometimes a full crank and then stops. Grounds are good, battery cables and connections are good, even hooked up jumpers and verified 12.5 volts from the battery. Need to know what it might be so I can get it home ASAP

Check the battery connections, especially at the starter solenoid. New? or are you sure the starter (I am assuming solenoid) are new.

did it start once it cooled down? how did you check the cables?

Not while I was trying it. It never fully cooled down before I had to leave, but it went from running temp down to almost not reading on the gauge and it didn't make a difference. I ran the cables and felt for breaks where maybe it was corroded inside the casing but didn't find any issues

how did you get it started? if it starts after cooling its either the timing is too advanced, heat soaked starter or weak cables

Gave me the same issues today, but after messing with the timing and cables a little bit she started with jumpers hooked up. Gonna replace the alt because it's only reading about 13 volts while running and replace the grounds for safety. Any other advice on how to make sure this doesn't happen again?

whats your timing at?