Make sure that TDC on the crank is for #1 rather than its opposite in the firing order. That is, on the compression stroke and not the exhaust stroke. Both intake and exhaust valves for cyl #1 should be closed. If you place a wad of paper in the #1 spark plug hole the compression should blow it out in dramatic fashion. Some prefer to use their finger for this - even more dramatic.

 

The vacuum gauge reading eliminates a few possibilities, good. 19" steady is real good for a high mileage engine. It also sounds like the accuracy of the timing marks are reasonable too. So 14° initial indicated is probably close the actual timing.

That still leaves the question though, 1. Why is the starter having trouble and 2. Why is there backfire at idle. Two different causes, may be they are unrelated.

It could simply be the starter is wearing out, or is defective. Neglected grounds, corroded or loose cables, etc. If they are original they should certainly all be replaced. Even 20 year old cables are suspect if the truck lives outside, rustbelt, etc. Going up (down) a size or two in gauge has proven to be effective manytimes in solving hot start issues. Might be interesting to perform a voltage drop test during cranking on the different cables and connections. Do the headlights dim out, or stay bright when cranking?

 

Put hose on vacuum advance port and either use a vacuum pump or suck on the hose to see if advance plate is moving freely.

 

So i hooked the hand pump up to the vac. advance and the gauge didnt climb at all. So i took it off and sure enough i can blow through it. Looks like ill be getting a new vac. advance tomorrow and trying again.

 

Mine stuck advanced. I put in 2 starters another battery positive wire and ground wire.Before we figured it out.

 

I'd maybe take a look at the breaker plate? If the vac advance diaphragm won't hold air, won't actuate the breaker plate, there won't be any advance to get stuck in the first place, if that makes any sense. Or maybe it's already stuck? Earlier units used a kind of ball bearing deal, later on switched to nylon bushings that seem a little more sketchy. For all that if the vac advance is toast the rest of the distributor may not be far behind.

 

Turned the motor over to TDC on the compression stroke on cylinder #1. The timing mark was way off and the rotor pointed between posts. So i marked TDC on the harmonic balancer then measured 14* past TDC from the original 0* and marked the new 14* from the new 0*. After playing with it for awhile i got it running and starting fine. I guess my harmonic balancer is off?? But thanks for all the help guys.

 

How much vacuum is it pulling now? 19" you were getting earlier meant the initial timing was very close to where it should be. I'd look at a rebuilt damper replacement, since it isn't absorbing anything if slipping. Cracked or busted crankshaft is a possibility with defective damper. Generally we want as much advance as possible without pinging at all times.