No Spark. Do ignition coils go bad?

[fine69]

Getting No Spark. Do ignition coils go bad?

In the past few days, two different people at Edelbrock tech support gave me two different recommendations: one instructed me to set my timing at 14 degrees BTDC at 900 rpm... well I tried that (with the vacuum line unhooked and plugged), now my car is running worse than before. When I shut it off, it dieseled.. then it wouldn't start... the carb just coughs up gas. Perhaps it was flooded - I'll try again today.
The other tech recommended 12-14 degrees at an 800 rpm idle! He also recommended "yellow step up springs" (not sure what those are for).
They both said that the Edelbrock fuel pump may actually be part of the problem. Although it's the street fuel pump (not their "high performance" one), it maybe pushing greater than 6 psi. I don't want to put in a regulator... so I'm going to switch it from the Edelbrock back to a stock GM.
I swear I am tempted to yank this whole engine out again, and go back to the stock specs... this is crazy.

I didn't want to hijack rgtrough's thread ("Total Timing") with my problems, so I'm starting a separate one.

Today I cleaned the carburetor, replaced the edelbrock fuel pump with a stock GM / Chevy fuel pump, and also replaced the spark plugs (this is the fourth set since my rebuild last November). I tried to start it... no change... just coughing and spitting though the top of the carb.

I removed a spark plug and low and behold, NO SPARK. I have one of those circuit testers that utilizes a small light. When testing the positive terminal of the ignition coil, it lights dimly (key turned to the accessory position) -- but no light from the negative terminal. When you crank the engine, the tester light becomes bright when reading both, positive and negative terminals.

Do ignition coils go bad? Is it possible part of my backfiring and misfiring problems could have been attributed to a coil that is faulty --- or going bad? I've never heard of this.

These "nickle and dime" replacements have added substantially; but if I have to get a replacement coil, so be it. I am NOT liking my Vette too much lately. ad

Please... any help is appreciated.

Thank you.

Ralph

 

[bossvette]

are you still using a point system? With all the work you have done it might be a good idea to use a more modern ignition to get the best results MSD makes a tach drive distributor just for Vettes like yours it will wake up that engine.

you can even get a rev limiting box which is a good idea.

 

[fine69]

are you still using a point system? With all the work you have done it might be a good idea to use a more modern ignition to get the best results MSD makes a tach drive distributor just for Vettes like yours it will wake up that engine.

you can even get a rev limiting box which is a good idea.

Yes, it's the stock, points-type ignition. I replaced the coil and now the spark plugs generate a very thin, small blue spark. The spark seems so weak! I recall a brighter spark when I did this previously.

 

[stxhank]

Make sure you are using an external tach as opposed to your in dash tach. Why? The in dash tach may be giving you false readings... borrow an external tach or go buy one you may be surprised.

 

[bossvette]

there are basically two types of coils those with a ballast resistor built in and those that use an external ballast resistor; if you use a coil with a ballast resistor built in with a ballast rsistor your spark will suffer.
Hopefully someone will come along that will know how to tell the difference.

 

[fine69]

there are basically two types of coils those with a ballast resistor built in and those that use an external ballast resistor; if you use a coil with a ballast resistor built in with a ballast rsistor your spark will suffer.
Hopefully someone will come along that will know how to tell the difference.

The replacement coil - as well as the old one, have a lebel that says "external resistor required" --- I am no sure where the resistor is located. The (+) post of the coil has two wires that connect to it. The (-) post has the black wire that connects to the distributor.

 

[fine69]

Make sure you are using an external tach as opposed to your in dash tach. Why? The in dash tach may be giving you false readings... borrow an external tach or go buy one you may be surprised.

Yes. I am using an external, digital readout type of tach for the tuneups.

 

[JohnZ]

I removed a spark plug and low and behold, NO SPARK. I have one of those circuit testers that utilizes a small light. When testing the positive terminal of the ignition coil, it lights dimly (key turned to the accessory position) -- but no light from the negative terminal. When you crank the engine, the tester light becomes bright when reading both, positive and negative terminals. Ralph

With the test light on the (+) terminal to ground, you shouldn't see any light unless the key is in the "on" or "start" position; there's no power to that circuit in the "accessory" position. You should get a brighter light while cranking than in the "on" position; while cranking, that second wire (yellow) feeds a full 12 volts to the coil from the "R" terminal on the starter solenoid - in the "on" position, the coil gets reduced (7-8 volts) through the white cloth-covered resistance wire from the ignition switch.

Did you do any other work besides what you outlined since it last ran (assuming it ran OK before you worked on it last)? Backfiring and misfiring are almost always ignition and/or timing-related, and when they get worse with heat, the coil is frequently the culprit. Coil wire fully seated in the coil and distributor cap? Ground wire inside the distributor from the breaker plate to the vacuum advance attaching screw in good shape (that's the ground for the points, and if that's flaky, spark will be flaky)?

You don't need any $500 "whizbang" electronic ignition system; your stock system will work just fine if it's set up properly. All my small-blocks have dead-stock point ignition systems, and they start in half a revolution and wind to the moon with no missing.

 

[fine69]

With the test light on the (+) terminal to ground, you shouldn't see any light unless the key is in the "on" or "start" position; there's no power to that circuit in the "accessory" position. You should get a brighter light while cranking than in the "on" position; while cranking, that second wire (yellow) feeds a full 12 volts to the coil from the "R" terminal on the starter solenoid - in the "on" position, the coil gets reduced (7-8 volts) through the white cloth-covered resistance wire from the ignition switch.

Did you do any other work besides what you outlined since it last ran (assuming it ran OK before you worked on it last)? Backfiring and misfiring are almost always ignition and/or timing-related, and when they get worse with heat, the coil is frequently the culprit. Coil wire fully seated in the coil and distributor cap? Ground wire inside the distributor from the breaker plate to the vacuum advance attaching screw in good shape (that's the ground for the points, and if that's flaky, spark will be flaky)?

You don't need any $500 "whizbang" electronic ignition system; your stock system will work just fine if it's set up properly. All my small-blocks have dead-stock point ignition systems, and they start in half a revolution and wind to the moon with no missing.

Thank you John. That's encouraging, I really don't want to convert to an HEI, or MSD system.

No, I haven't done any additional work other than trying to get run "correctly" (I haven't even accomplshed that yet).

I gave inaccurate information in my previous post. When testing the positive terminal of the ignition coil, the tester lights dimly (key turned to the ignition position not the accessory position).

I was ready to throw in the towel today, but I found that the condenser wire was broken at the screw. I repaired the wire, hooked it up and got a spark again (yea!)... but that's my only good news.

... So again, I went through the process of finding TDC, and setting the distributor to #1 wire, etc., gapped the plugs to .035. I don't have a dwell meter yet, so I set the point gap at .019 to get started as instructed in the Haynes Repair Manual. I've attached some pics of the set up.

I did finally got it started again, but it is running terrible. I attempted to set the base timing (vacuum adv hose disconnected and plugged) to 14 degrees BTDC at 900 RPM... no way! To keep it running, I have to keep the RPMs around 1200-1400. The engine is still awfully rough... not a cam lope... rather, the sound is more erratic. I noted that the driver's side carburetor jet constantly drips. It does shoot a nice spray at throttle, but goes back to the drip.

What am I doing wrong? Could my distributor position be off by a tooth or so?... If the rotor lines up in the vicinity of #1, wouldn't the exact positioning be corrected when rotating the distributor assembly? :confused

Thank you.

Ralph

 

[bossvette]

I am not familiar with Edelbrock carbs, but it looks like the vacuum line is hooked to a spot above the throttle blades and the port on the right side looks to be lower and should be a full vacuum port, Barry posted a link to JohnZ's article on one of these threads give it a read.
You may want to check your grounds if you still have a weak spark; over time they can become corroded and missing.

 

[huk_finn]

did you to line up the timing mark "on the compression stroke" (720 degrees of crank rotation on a 4 stroke engine cycle).

 

[JohnZ]

What am I doing wrong? Could my distributor position be off by a tooth or so?... If the rotor lines up in the vicinity of #1, wouldn't the exact positioning be corrected when rotating the distributor assembly? :confused

Thank you.

Ralph

This may sound redundant, but make sure you're at #1 TDC on the compression stroke with the timing marks lined up; pop the driver's side valve cover off and verify that both valves are closed on #1 (rocker arms parallel). If they're not, you're on #6 TDC, and need to turn the crank one full rotation to be on the #1 compression stroke.

Also, check the wire indexing in the cap and make sure they're 1-8-4-3-6-5-7-2, and make sure you don't have #5 and #7 reversed at either end.

 

[74bigblock]

Thank you John. That's encouraging, I really don't want to convert to an HEI, or MSD system.

No, I haven't done any additional work other than trying to get run "correctly" (I haven't even accomplshed that yet).

I gave inaccurate information in my previous post. When testing the positive terminal of the ignition coil, the tester lights dimly (key turned to the ignition position not the accessory position).

I was ready to throw in the towel today, but I found that the condenser wire was broken at the screw. I repaired the wire, hooked it up and got a spark again (yea!)... but that's my only good news.

... So again, I went through the process of finding TDC, and setting the distributor to #1 wire, etc., gapped the plugs to .035. I don't have a dwell meter yet, so I set the point gap at .019 to get started as instructed in the Haynes Repair Manual. I've attached some pics of the set up.

I did finally got it started again, but it is running terrible. I attempted to set the base timing (vacuum adv hose disconnected and plugged) to 14 degrees BTDC at 900 RPM... no way! To keep it running, I have to keep the RPMs around 1200-1400. The engine is still awfully rough... not a cam lope... rather, the sound is more erratic. I noted that the driver's side carburetor jet constantly drips. It does shoot a nice spray at throttle, but goes back to the drip.

What am I doing wrong? Could my distributor position be off by a tooth or so?... If the rotor lines up in the vicinity of #1, wouldn't the exact positioning be corrected when rotating the distributor assembly? :confused

Thank you.

Ralph

Ralph... your Vaccum advance is on the wrong side of the Edelbrock carb. It should be on the right hand port if you are facing the carb from the front position. The left side is for your Tranny kick down on an automatic.

Switch it and see what happens. Make sure to cap off the left side if you have a manual trans.

Dave

 

[fine69]

Ralph... your Vaccum advance is on the wrong side of the Edelbrock carb. It should be on the right hand port if you are facing the carb from the front position. The left side is for your Tranny kick down on an automatic.

Switch it and see what happens. Make sure to cap off the left side if you have a manual trans.

Dave

Thanks Dave,

Yes, John Z informed me that this is incorrect. I was instructed categorically by Edelbrock tech support to use that port (can you believe that?).

Although I spent a great of time and $$ on this rebuild, I'm going to remove the engine again and change the cam to something more streetable.

Ralph

 

[74bigblock]

Thanks Dave,

Yes, John Z informed me that this is incorrect. I was instructed categorically by Edelbrock tech support to use that port (can you believe that?).

Although I spent a great of time and $$ on this rebuild, I'm going to remove the engine again and change the cam to something more streetable.

Ralph

Good luck! I feel your pain.