No Spark
Thread Starter
Cruising
Joined: Nov 2012
Posts: 12
Likes: 0
No Spark
Hello. I have a 71 vette. 350 ci auto trans. Car ran perfectly before stored (several years ago) I can't get any spark to the plugs or out of the coil. Have replace plug wires, points, cap, rotor, coil. Checked voltage at coil and starter solenoid, All these seem to check out fine. Not sure what to check next. Any ideas much appreciated!
Intermediate
Joined: Sep 2012
Posts: 35
Likes: 0
Have a helper hold the key to the start position and make sure that you have approx 12 volts at the plus side of the coil WHILE THE KEY IS HELD IN THE START POSITION. You must have the voltage there while the ignition switch is in BOTH the start and run (on) positions. Perhaps you just checked it with the key in the on position only?
If this checks ok, try replacing the big wire from the coil to the distributor. A forum member friend of mine recently had one of these fail unbeknowst to him when he pulled it loose to remove the distributor. They can become brittle, the carbon string inside breaks, and they appear fine. Also make sure that your points are opening and closing properly and have not slipped/closed up. About a .017 gap is a good place to start. As you know, the points opening is what causes the magnetic field in the coil to collapse and generate a spark.
Check the black wire from the points to the coil for tight connections/breaks/chafes. Test it for continuity with a meter.
If this checks ok, try replacing the big wire from the coil to the distributor. A forum member friend of mine recently had one of these fail unbeknowst to him when he pulled it loose to remove the distributor. They can become brittle, the carbon string inside breaks, and they appear fine. Also make sure that your points are opening and closing properly and have not slipped/closed up. About a .017 gap is a good place to start. As you know, the points opening is what causes the magnetic field in the coil to collapse and generate a spark.
Check the black wire from the points to the coil for tight connections/breaks/chafes. Test it for continuity with a meter.
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
I've seen the wire from the coil to the distributor break, the points set with an oily feeler gauge, the condenser bad out of the box, the screw that holds the primary wire and the condenser lead shorted or the leads mis-installed on it, the ground from the breaker plate to the distributor housing broken, and the coil bad. Take your pick.
Thread Starter
Cruising
Joined: Nov 2012
Posts: 12
Likes: 0
still no spark
Thanks for all the tips. Unfortunately I still can't get spark out of coil or to plugs. All the wiring has continuity (Coil to points, coil to starter)., points new and set proper (open & close), new plug wires, cap, rotor. I have 12 volts at coil when ign switch is in on pos and also start pos.
I know it has to be something simple but I can't seem to find the issue. Any more thoughts or suggestions? Thanks!
I know it has to be something simple but I can't seem to find the issue. Any more thoughts or suggestions? Thanks!
Racer
Joined: Jan 2005
Posts: 365
Likes: 1
From: Glenview IL
Thanks for all the tips. Unfortunately I still can't get spark out of coil or to plugs. All the wiring has continuity (Coil to points, coil to starter)., points new and set proper (open & close), new plug wires, cap, rotor. I have 12 volts at coil when ign switch is in on pos and also start pos.
I know it has to be something simple but I can't seem to find the issue. Any more thoughts or suggestions? Thanks!
I know it has to be something simple but I can't seem to find the issue. Any more thoughts or suggestions? Thanks!
Thread Starter
Cruising
Joined: Nov 2012
Posts: 12
Likes: 0
I hold the spark plug wire(s) and also at another time the coil wire (still in the coil but out of the cap) approx 1/4" from a ground while cranking the engine over. Engine cranks perfectly but no spark. Thanks!
Melting Slicks
Joined: Aug 2012
Posts: 2,548
Likes: 379
From: Woodinville WA
when the ignition switch is "on"
when you break the contact between the points, does it spark? when do the points open in relation to the rotor? (oh lord I hate dwell)
Are you getting spark from the coil? put a spark plug on the coil (or hold - or preferable your "helper"
) the coil lead next to a ground, then open the points - does it discharge? if not, it's probably a bad coil
what voltage are getting to the coil? there's a resistor that should be reducing the line voltage (although, normally if it's getting power, it's fine - it'll just burn the coil up eventually)
Is the wire from the starter to coil connected?
when you break the contact between the points, does it spark? when do the points open in relation to the rotor? (oh lord I hate dwell)
Are you getting spark from the coil? put a spark plug on the coil (or hold - or preferable your "helper"
) the coil lead next to a ground, then open the points - does it discharge? if not, it's probably a bad coilwhat voltage are getting to the coil? there's a resistor that should be reducing the line voltage (although, normally if it's getting power, it's fine - it'll just burn the coil up eventually)
Is the wire from the starter to coil connected?
Thread Starter
Cruising
Joined: Nov 2012
Posts: 12
Likes: 0
I've got power going to the points 12v, but don't notice any spark when they open and close when I'm cranking the engine over. Rotor lines up at #1 TDC - looks proper.
No spark from the coil when I run the wire near a ground to try spark - it's a new coil. Points open and close. FYI - Even though there is what appears to be a proper gap on the points and the fully close and open when I hook a dwell meter up it doesn't register at all - any ideas?
Getting right at 12v at coil from ign switch and also down at starter (wire from coil).
This one's got me stumped
No spark from the coil when I run the wire near a ground to try spark - it's a new coil. Points open and close. FYI - Even though there is what appears to be a proper gap on the points and the fully close and open when I hook a dwell meter up it doesn't register at all - any ideas?
Getting right at 12v at coil from ign switch and also down at starter (wire from coil).
This one's got me stumped
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Intermediate
Joined: Sep 2012
Posts: 35
Likes: 0
Make sure the small wires on the coil are not hooked up backwards. The small black wire from the distributor points is connected to the terminal marked - neg on the coil. The resistor wire coming through the firewall is connected to the + pos terminal on the coil. You can have them connected backwards, and still read the 12 volts on the resistor wire with the key start/on, but no voltage build up will occur inside the coil.
Racer
Joined: Apr 2012
Posts: 464
Likes: 1
From: Austell Georgia
Maybe you got a bad coil out of the box. Have you done a resistance check on the coil? .5 to 2 ohms across the + and - terminals. 7k-11k ohms from either terminal to the center post. Rough numbers but should be close.
Intermediate
Joined: Sep 2012
Posts: 35
Likes: 0
I know you said you replaced the big wire from the coil to the distributor cap, but if you haven't done so yet, get another one (Autozone sells cheap ones seperately, grab one off another car, or whatever) and try it. I know, this is too simple, but I have seen it more than once. It may look perfect outside, but it is nothing more than a carbon coated string. They break inside all the time. Let us know what fixes it.