Slow cranking with a new battery...won't start

[Righty Tighty]

I just bought my '74 Barracuda, and it had been sitting for at least a decade prior to me bringing it home. I've gone through everything and freshened fluids, changed filters, etc., before starting it for the first time.

Well, all that was done and now it's time to start it. Fresh battery, new starter relay, new ignition mod, new cables, and I've ensured a good ground. The old, full size starter is still in the car. It's cranking VERY slowly, and eventually stops cranking. Depending on the day, I usually have around 12.5-13.5V at the battery, 5V at the coil while connected, 12V on the coil wire when disconnected.

I tried the screwdriver trick to check for spark, but I can't see a spark either from the plug wires or the coil wire. I'm not sure I'm doing the test right, so I got an actual plug tester that lights up upon cranking. Hopefully that will give better results.

I bought a new mini starter from a '91 Dakota, hopefully that will help, but I suspect there may be more than one problem I'm dealing with. Can anyone help with some troubleshooting tips?

 

[NoCar340]

The first thing I would do is a voltage-drop test on the battery cables with a multimeter. It doesn't matter how good they look, they can be solid green fuzz inside of gorgeous insulation.

First, check the battery right at the posts. Leave your red lead on BAT (+), but move the black to the starter housing itself or a mounting bolt/stud. It should read very close to battery voltage (within .1-.2V). If it does not, move the black lead to negative cable lug at the engine. If it's low there, the negative cable is suspect. If it's not, it may be rust/paint/dirt at that cable connection. Remove the bolt, clean everything, and retry.

Now reverse the test by putting the black lead on BAT (-) and move the red lead to the battery cable stud on the alternator. Again, it should be very close to battery voltage. If it's not, replace it.

Advanced timing can cause slow cranking, but it's most often a hot-start issue. Still, it's worth turning the engine until the damper's pointer is at zero on the timing scale, and popping off the distributor cap. The rotor should be pointing almost directly at either the #1 or #8 plug-wire terminal. If you want to verify that the distributor's not installed 180° out, remove the #1 spark plug before turning the engine to TDC. Hold your thumb over the plug hole. When you feel pressure against your thumb coming up to TDC, stop at TDC and verify that the rotor is pointing almost directly at the #1 plug wire on the cap.

Those are worthwhile tests to make on any newly-bought vintage rig, but I would not be surprised to find out that it's the starter itself. Those old Mopar gear-reduction units will run themselves literally to death... they get slower and slower until one day, no crank. If it's not timing or cabling, the battery's good (and fully charged) and the engine doesn't feel tight while turning over by hand, it's almost got to be the starter.

 

[NoCar340]

Oh, yeah... one problem at a time. Figure out the slow cranking first, then worry about whether it'll start.

 

[moparleo]

Did you put any lubricant into the cylinders to free up the rings and any potential cylinder wall rust from sitting so long ?
Have you tried cranking with the spark plugs removed to see how fast it cranks with no load ?
http://www.tpocr.com/dodge2.html

 

[Righty Tighty]

It STARTS!! Turns out the starter was bad. However, the choke won't open. If I hold it open, the engine runs great. I need to figure out why the choke isn't working.

In reply @moparleo, I did pre-lubricate the cylinders, but I didn't try cranking without the plugs installed. To be honest, it was such a pain in the ass to take the plugs out, I hadn't thought of anything besides getting them back in.

 

[Righty Tighty]

The first thing I would do is a voltage-drop test on the battery cables with a multimeter. It doesn't matter how good they look, they can be solid green fuzz inside of gorgeous insulation.

First, check the battery right at the posts. Leave your red lead on BAT (+), but move the black to the starter housing itself or a mounting bolt/stud. It should read very close to battery voltage (within .1-.2V). If it does not, move the black lead to negative cable lug at the engine. If it's low there, the negative cable is suspect. If it's not, it may be rust/paint/dirt at that cable connection. Remove the bolt, clean everything, and retry.

Now reverse the test by putting the black lead on BAT (-) and move the red lead to the battery cable stud on the alternator. Again, it should be very close to battery voltage. If it's not, replace it.

Advanced timing can cause slow cranking, but it's most often a hot-start issue. Still, it's worth turning the engine until the damper's pointer is at zero on the timing scale, and popping off the distributor cap. The rotor should be pointing almost directly at either the #1 or #8 plug-wire terminal. If you want to verify that the distributor's not installed 180° out, remove the #1 spark plug before turning the engine to TDC. Hold your thumb over the plug hole. When you feel pressure against your thumb coming up to TDC, stop at TDC and verify that the rotor is pointing almost directly at the #1 plug wire on the cap.

Those are worthwhile tests to make on any newly-bought vintage rig, but I would not be surprised to find out that it's the starter itself. Those old Mopar gear-reduction units will run themselves literally to death... they get slower and slower until one day, no crank. If it's not timing or cabling, the battery's good (and fully charged) and the engine doesn't feel tight while turning over by hand, it's almost got to be the starter.

That's exactly what I was looking for, thank you!