No spark I Install new distributor?

Tiny
JOE1953
  • MEMBER
  • 1979 FORD F-100
  • V8
  • 2WD
  • AUTOMATIC
  • 300,000 MILES
I Install new distributor, new spark plugs wires. Engine will crank but no start no spark from spark plug wire. What is the firing order on this engine? I'm not sure that I install the distributor correctly.
Wednesday, November 26th, 2025 AT 10:01 PM

9 Replies

Tiny
STEVE W.
  • MECHANIC
  • 15,231 POSTS
79 could have a 302, 351, 400 or 460. There are 2 possible firing orders depending on which engine you have if it's the original engine. Set it on TDC cylinder one on the compression stroke. Then pull the cap off and look at where it's pointing. If it's at a terminal post, make that #1 and wire around counter clockwise following the correct order. Put a spark tester on the coil wire and see if it has spark out of the coil. If you have spark out of the coil and it's wired correctly then you should be able to put a timing light on the cylinder one wire and set the base timing.
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Thursday, November 27th, 2025 AT 2:41 AM
Tiny
JOE1953
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I Put a spark tester on the coil wire to see if it has spark out of the coil. There was no spark out of the coil. What is the number for the timing? How do I know what engine is in the pickup truck?
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Thursday, November 27th, 2025 AT 7:29 AM
Tiny
STEVE W.
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OK, no spark from the coil can mean coil or the trigger is bad or more common the ESC box is bad. To test the coil is simple. Take a piece of wire, connect it to a good ground, connect the spark tester to the coil wire, turn on the key, now tap the grounded wire on the negative coil post, do you get a nice hot spark Yes= Coils Good, No= replace the coil. See if you have spark. Still no spark = find the box shown, Find the part number on it, get a replacement. As for engine size, if it's stock there should be a sticker on the radiator support that tells you the engine size, timing and spark plug gap.
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Thursday, November 27th, 2025 AT 2:30 PM
Tiny
JOE1953
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What type of spark tester do I need to do this test?
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Friday, November 28th, 2025 AT 6:59 PM
Tiny
STEVE W.
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Just a simple gap style tester, you could even use a plug wire and a plug. You are just testing if the coil fires on it's own.
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Friday, November 28th, 2025 AT 8:07 PM
Tiny
JOE1953
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I took a piece of wire, connect it to the negative side of the coil and I disconnect wire from the distributor cap and connect a spark plug into it and turn the key on and tough the piece of wire to a ground, the spark plug didn't spark unless I wiggle the key but as soon as I stop wiggling the key the spark plug stop sparkling, will that be something wrong with the Ignition switch? I also connect my test light to the positive side of the coil and turn on the key the test light come on bright, but when I connect the test light to the negative side of the coil my test light is dim, but when I wiggle the key the test light brightness up so what is going on here?
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Saturday, November 29th, 2025 AT 4:34 PM
Tiny
STEVE W.
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That sounds like the coil is OK but the ignition switch has a problem. How long has this truck sat around? It could be corrosion that some contact cleaner would help with, however being a 79 it may just need a new switch.
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Saturday, November 29th, 2025 AT 7:13 PM
Tiny
JOE1953
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The truck was cranking and starting about a year ago with the key but it stop cranking with the key then I use a Jump wire to crank it from the starter switch to the battery, the engine and transmission was taken out for a rebuilding Job so aften it was put back in that when the engine stop starting. How can I do a bench test on the Ignition starter switch?
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Saturday, November 29th, 2025 AT 7:49 PM
Tiny
STEVE W.
  • MECHANIC
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You pretty much already tested it. If it stopped cranking with the key then it likely isn't turning on the power to the ignition either. They are all related. The switch controls power to all the other areas and if it's not spinning the starter and now the power to the coil is out unless you jiggle the key, that sounds like a bad switch.
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Saturday, November 29th, 2025 AT 8:44 PM

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