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Post by class115 on Jun 2, 2018 16:22:00 GMT -5
Tom, I have been praying that it's not the timing chain. I will test the coil voltage for the two cases you suggested; cranking and key in start. Standby while I bargain with my wife to help me. I'll also check the spark at each wire. Just to double check, Where do I put the negative lead when doing the coil test? On the negative terminal or any ground?
As far as war stories- my dad's 77 Dodge Maxivan with a 318. He bought it used in 1979 form I guy who put blue and brown shag carpet on the floor, walls, and dashboard. (and paneling on the inside of the roof. One day we had a carb backfire with engine cover and air cleaner off. Singed the carpet on the dash and chared the paneling on the roof. Awesome!
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DynoDave
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Post by DynoDave on Jun 2, 2018 17:06:39 GMT -5
I too wondered about the timing chain, but just didn't want to go there.
It is possible too that your vibration damper has slipped, and while it may appear to be in time, it is not.
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Tom
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Post by Tom on Jun 2, 2018 17:15:16 GMT -5
Put the negative lead on any ground.
No better ground than battery - if your leads are long enough.If not...any ground is fine.
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Tom
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Post by Tom on Jun 2, 2018 17:21:32 GMT -5
I would not necessarily check spark at end of every single wire, I'd probably just check 2-3 randomly. You are just wanting to verify what is going in the distributor (spark) is coming out and getting to the cylinders
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Post by class115 on Jun 2, 2018 19:33:40 GMT -5
Tom, Got it, I'll check a few.
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Tom
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Post by Tom on Jun 2, 2018 20:05:14 GMT -5
When you tested for spark out of the coil wire, how would you describe what you saw/heard?
I know that may sound weird...but it could be helpful. The spark out of the coil/coil wire should be pretty strong....... a good consistent snap-crack sound.
For example....On Ford coil on plugs, a good coil makes a good loud snap sound. Weak coil, you can see a spark...but different color and don't hear it as loudly.
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Post by class115 on Jun 2, 2018 21:09:39 GMT -5
When you tested for spark out of the coil wire, how would you describe what you saw/heard?
I know that may sound weird...but it could be helpful. The spark out of the coil/coil wire should be pretty strong....... a good consistent snap-crack sound.
For example....On Ford coil on plugs, a good coil makes a good loud snap sound. Weak coil, you can see a spark...but different color and don't hear it as loudly.
I'll do it again and report back, I don't remember a noise, but it was loud under the hood. I know I set the tool gap to 30. I expected to see a faint blue spark, but that thing lit up blue-white and startled me. I could probably set it on 40 and get a spark. After I saw that spark, I really thought re-setting to the reluctor gap to spec. was going to be the answer.
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Post by class115 on Jun 2, 2018 21:21:39 GMT -5
I too wondered about the timing chain, but just didn't want to go there. Dave, You dusted off the cobwebs. The last time it ran in early May, it backfired but started, I went to check the timing with a digital timing light. The light said 850-900 rpm, but the tack in indicated over 1000-1100 rpm. It is a Classic Instruments in-dash tach. I just thought the tach was dying, or the timing light was going bad. I didn't touch or adjust anything. It never started since.
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Post by class115 on Jun 3, 2018 17:15:32 GMT -5
It started, no priming. I was working on getting Tom some answers. (I didn't hear a crack with the spark tester. The battery had 12.55v. Voltage @ coil read between 16.5 mV and 20 mV with Ign in run. Voltage @ coil read between 7.78V and 9.47 V when cranking). Since I changed everything else, I tried the ignition switch. I unplugged, it plugged in a new one and it started. The boom, the backfire was due to me trying to start it the with the gas pedal I guess. The backfire lead me and everyone else astray. Last time I had a bad ignition switch (15 years ago), I never got a backfire and I know I was pumping away on the gas back them as well. Thank you THANK YOU for all those who took the time to brainstorm this with me.
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Tom
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Post by Tom on Jun 3, 2018 18:46:24 GMT -5
So, a new ignition switch fixed the problem? That is what the voltages that I asked you to check were verifying.
The voltage reading you had in run position (basically nothing) was indicative of a bad IGN switch.
Glad you got it figured out and that the solution is relatively inexpensive.
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