H4 magneto spark from coil to cap no spark from cap to wires

Something different...

Remove all the plug wires at the distributor. Take a length of 14 awg (or whatever you have) wire and strip the insulation. Next bend a 1 inch long narrow half loop on one end of the wire and slip into distributor post 5... then create another loop for 3, 1, 4, 2, and 6. Position loose end of wire near engine metal. Crank engine.

Regardless of timing, you should see a spark.

Comment for further assistance.

check cap and rotor installed correctly --wires seated and rotor making contact --didnt get knocked off timing --or off by 180 deg

I guess you could have the ignition analyzed on an oscilloscope. Maybe a tech could see something then.
I always heard the only gap was the spark plug gap-the rotor has no gap-are you sure you got the correct rotor? And does it touch the top distributor cap coil wire tower?

Let us know. It is a mystery worthy of a solution.

Firing order is 1-3-4-2 Please rate if this helps

Installation of wires

1. Whenever a high tension wire is removed for any reason from a spark plug, coil or distributor cap, or a new high tension wire is installed, Silicone Dielectric Compound WA-10, D7AZ-19A331-A (ESE-M1C171-A) or equivalent must be applied to boot before it is reconnected. Using a small clean tool, coat entire interior surface of boot with Silicone Dielectric Compound WA-10, D7AZ-19A331-A (ESE-M1C171-A) or equivalent.

1. Insert each wire on proper terminal of distributor cap. Ensure wires are all the way down over their terminals. The No. 1 terminal is identified on cap. Install wires starting with No. 1 terminal.

1. Remove wire retaining brackets from old high tension wire set and install them on new set in same relative position. Install wires in brackets on valve rocker arm covers.

1. Connect wires to proper spark plugs.

1. Install coil wire.

Installation of distributor
Before installing distributor, visually inspect distributor. Inspect O-ring. It should fit tightly and be free of cuts. The drive gear should be free of nicks, cracks and excessive wear. Rotate distributor drive shaft. It should move freely, without binding.

1. To install distributor correctly, No. 1 piston must be at Top Dead Center (TDC) of compression stroke. Remove No. 1 cylinder spark plug and rotate engine clockwise until No. 1 piston is on the compression stroke.

1. With No. 1 piston on compression stroke, align timing pointer with TDC on the crankshaft damper.

1. Align locating boss on rotor with hole on armature. Fully seat rotor on distributor shaft.

1. Rotate distributor shaft so blade on rotor is pointing toward mark on distributor base, that was previously made in Step 2 of the Removal procedure.

1. While installing distributor, continue rotating rotor slightly so leading edge of the vane is centered in vane switch stator assembly.

1. Rotate distributor in block to align leading edge of vane and vane switch stator assembly. Verify rotor is pointing at No. 1 mark on distributor base. If vane and vane switch stator cannot be aligned by rotating distributor in cylinder block, remove distributor enough to just disengage distributor gear from camshaft gear. Rotate rotor enough to engage distributor gear on another tooth of camshaft gear. Repeat Step 1 if necessary.
   

1. Install distributor hold-down clamp and bolt. Tighten bolt, but leave it loose enough to rotate distributor.

1. Install distributor cap, No. 1 spark plug and ignition wires. Check that ignition wires are securely connected to the cap and spark plugs. Tighten distributor cap hold-down screws to 2.0-2.6 Nm (18-23 lb-in).

1. Reconnect distributor to wiring harness.

1. Set initial timing according to procedures found in Section 13A of the Powertrain Control/Emissions Diagnosis Manual .

1. After timing is set, tighten distributor hold-down bolts to 23-34 Nm (17-25 lb-ft).

1. Recheck initial timing. Adjust if necessary.

Did you place the spark plug wires in the correct order?

Hi Friend:

YOUR firing ORDER IS 1-8-4-3-6-5-7-2 Clockwise Rotation.

Facing your Truck heres where your Cylinders Are.

Front Of Truck

1-------------------------------------2

3-------------------------------------4

5-------------------------------------6

7-------------------------------------8

This should help you getting your firing order correct.

To Find where top dead center is at and thats where your #1 Plug Wire would go.

First remove your Coil wire so it will not Start.

Then pull out #1 spark plug ,and while someone just bumps your engine on & Off until you are on Compression Stroke, You can just put your finger in the outer edge of where #1 Plug went and when the Air trys to push yuor finger out of #1 Spark Plug hole.

STOP.don't Crank it no more ,cause you are at Top Dead Center (TDC) ,Then takeoff your distributor cap and look at the way your Rotors pointing,Then where ever the rotors pointing is also where #1 Spark Plug wire will go.

NOTE: Sometimes the rotor will be just a little past where #1 Plug wire goes in your Distributor Cap,If its in between two of the Spark Plug Wire Sockets Then start #1 at the One over to the Right.

Hope I have given you enough info. on Possible Solutions,I would start at the first i Gave you,and work your way down.

Thanks For Using FixYa Please let me know how I've Helped you by Voting for me on the Quality of my Solutions.
Thanks again From: Your Expert d_hubbs

make sure firing order is correct if so then get motor at top dead center..If you dont know how to do this obtain a book and follow detailed procedure.....(it is fairly simple) once at top dead center pull dist. cap and see if rotor points directly to spark plug wire # 1 on cap...If not loosen distributor and turn until rotor is pointing to #1 wire

Hi: 1st thing to do is pull #1 Spark Plug AND before you Crank The Engine PULL COIL WIRE so your car does'nt Start During Your ommpression Test.Once you have commpression coming out #1 Spark Hole.Then follow the #1 Spark Plug Wire up to the Distributor Cap-Now Mark that #1 Wire with a Marker ,Sting any Way you'll know where it is on your Distributor.Now PULL Distributor Cap and see where the Rotor Is,It should be Pointing toward that #1 Spark Plug Wire. Could be a Little Past.. If all This Lines up and Tested Out right,Then ALL you Need to Do is Clean and Mark Your Timing to What you Car is in Time, Could be TDC (TOP DEAD CENTER) or 4-8 Degrees BTDC (Before Top Dead Center.And then put coil wire in and attach your timing light to #1 Wire And Loosen the Distributor Hold Down Bracket Under Distributor.Where You Still have a Little Resistance to Move it Clock or Counter Clock Wise. Start the vehice and Slowly Move the Whole Disributor Until You Get The Timing Light At the Timing Mark you Made. Thats It. Hope this Helps You Out. From The WYOCWBOY

Hi wyocwboy here, Have you changed Spark Plug Wires ,or distributor Cap & Rotor? If you have this really sounds more like a Few spark Plug Wires have Been put on wrong. If you have'nt changed opr moved any of the wires or changed cap & rotor,Its Possible that your Timing Chain has jumped a Notch.Clean off your Damper -Which is the Bottom Pully your Hamonic Balacer, then rotate your enging until you Find your Timing Marks, Clean good and take a Marker or best a Chalk or Soap stick and mark it a 8 Degrees BTDC (Before Top Dead Center) Hook up a Timimg like Assuming it does run.And see if your able to see the Timing light Flashing on the mark if not Rote your Distributor either way Slowly and See if you can get the Light on the MARK you Made on The Harmonic Balancer. If Not Either Your Timing Chain Jumped a Notch or your Distributor may be off a nocth. To Check to see if your Timing Chain Jumped a Notch =Remove the COIL WIRE from Distributor Cap So it Won't Start then Remove #-1 Spark Plug Have a Friend Turn the Key off and On just Bumping the Engine a Little at a Time,Keeping a Compression Gauge in the #-1 Plug Hole When the Gauge Needle goes up you are close to TDC (TOP DEAD CENTER) STOP THERE .Check to see if the Mark on your Bottom Pully you made is at or Close to Ling up on top dead center. Trace #-1 Spark Plug Wire up to the Distributor Cap Remember the wires In the Dist. Caps Position or mark it to. Pull the Cap off The Distributor Rotor Should Be Pointing to Close to Where Your Number 1-Spark Plug Wire was Located.
Run These Series Of Tests and it Should Tell you or Give you a Very Good Idea of Your Problem. Please Let Me Know if This Helped You. FROM THE WYOCWBOY

Hello;
Take the distributor cap off, and turn the engine over. Does the rotor turn? Then pull the #1 spark plug and with your finger over the spark plug hole , tap the engine over to top dead center. See where the rotor is pointing. Also check to ensure your points are opening and closing. With an ohm meter make sure you have continuity through the carbon for the coil in the cap. Hope it helps.
Thanks;
Rich
RPM Northwest