Hot Rods SBC, points ignition, loses spark

OK.
Calmly repeat after me: "Working on old cars is FUN!" One more time: "Working on old cars is FUN!

Did that help?

Na, it doesn't help me either, but its the only excuse we have that keeps us doing this stuff.

 

Hehehe!

 

had more than a few of these. set points at .017 if not running. If running, use dwell spec w/ meter, forgot it but you can find it. New coil, not hot rod type, just a good stock coil. Wiring MUST be correct with no shorts, check all with meter. Use lots of advance. Don't remember if a ballast resistor was used, these came out first on FI vette's like in '57 or so. Think a 270hp 283 had 'em also. Look up a wiring diagram for these. Should also give specs, settings for one.

 

Looks like your chasing your tail now, I agree check the key switch it sounds like its shutting the engine off.

 

YEAH. Maybe grab a toggle switch . Hot wire, 12ga, from the BATTERY to one post on the toggle switch. From other post on toggle switch a 12ga wire to + post on coil. Direct, byp***ing all else. See what happens.

Ben

 

Well, the engine is still starting and running.
The tach that was on there and acting squirrely, i took off completely.
I checked the voltage at the ignition lead coming outof the starter switch: 14.4 steady volts when running. Then next going into the fuse panel:14.2 steadyvolts. Then after the 15 amp fuse coming out of the panel: 14.1 steady volts. Then at the end of that wire going into the ballast resistor: fluctuateing between 11- occasionally 3 volts.
So everything checks out fine from switch through the fuse panel.
I guess the next step is to jump around that wire and test, or just go ahead and excavate that wire from the 'Harness' and examine it, maybe put new connectors on it, or just replace it altogether.

 

Looks like you've almost got it licked there.

 

Thanks Man, i really appreciate you checking in with suggestions. You helped me get it going again.

 

So i dis-connected the wire from the fuse panel to the ballast resistor and put jumper wire in to test. The running voltage was mostly between 11-12 volts then 7 or 8 then back up to 12 sometimes flashing down to 3 for a second. So no real change with the new jumper wire.
It was 14 v at the panel, but over 3-4 ft of 14 g wire, it drops and is a bit erratic.
Is this normal? Is my wire too small?

 

I would think a 14g wire should be heavy enough for a 12 volt system on a 4' long run. Its really strange that the voltage at the fuse panel is consistent, but the voltage at the end of a 14G wire is not. Is it possible that the connections on either end (or both ends) of that jumper wire may be making a poor connection? Loosing one volt a foot (or more) seems pretty high on a 3-4' long 14g wire, are you sure the jumper wire is good?

 

What kind of meter are you using? If it's digital the proximity to the ignition system may be causing it to pick up interference and show more or less random values.

 

Looking at the pic of the ballist, it appears you have a red wire bridging the resister, this byp***es the resister and will over heat the coil and in time cook it. Also the coil looks like it belongs in a museum.
You should have two wires on the positive siditch e of the coil one from the ign. switch ( Run position) via the ballist and the other from the starter solinoid. JW

 

Hehehe, JW, the old coil is a good, old spare i was using while i was switching them out for trouble shooting. I have a new shiney one back on there now. It's funny 'cause its not as old as many of the other hard parts on the engine and ch***is.
The red wires just look like they are bridging the ballast resistor in the pic. They are not.
I don't have a second wire feeding the coil from the starter solenoid. Its seems to work fine on "start up". I have a second Ford style solenoid over by the starter, the starter solenoid is wired direct to the big post on the starter.

 

I think the jumper wire is good , it is new and i put new connectors on it. It's giving the same results on my meter as the old one.

 

It's a cheap digital unit. I will try to test it as far away from electrics as the leads will allow and see if it changes.

 

What voltage coils are you using? If it's a 12 volt item the resister drops the imput to the coil to around 8 volts, this happens over a very short time as the resister heats up, causing resistance happening, all my cars that run a ballist resister run a 6 volt coil. When you hit the starter it is like short with most of the power heading there and resulting in a voltage drop everywhere else( 10 volts ruffly) like your ignition and thats why the coil should have power to the coil at start up taken from the correct terminal on the starter solinoid. This is how my SBC in my RPU is done.JW

 

JW, it is a 12 volt coil.

 

Sounds like you've jumped out all the ignition power feeds and the problem persists. Wonder if the dist. is losing it's grounding at the block. Add a ground wire to the dist. body to see if that makes a difference. Oil and paint are good insulators and could be causing loss of grounding at the dist.

 

If your resister is wired correctly you are not supplying the coil with enough power to run it as i have said. You can try this by byp***ing the resister and supply straight 12 volts to the coil. Its actually very simple. If you uun a 12 volt coil it needs 12 volts supply and if you run a ballist risister you are only giving the coil around 8 volts after start up....there lies your problem, and a distributor is not going to lose grounding after 30 second every time you start it. JW

 

The car has been starting and running fine since i replaced the primary wire from the neg. coil terminal to the points.

The issue i currently am concerned with is why the voltage is fluctuateing, while the engine is running, from the fuse panel to the feed side of the ballast resistor.
I jumped the section with a brand new piece of 14 g wire and good connectors and it gives the same readings: 14 steady volts at the panel, then a fluctuating 12-11 mostly, or 8-7, but sometimes down to 3 for a moment. ?

 

When checking the voltage, where are you grounding your meter?

Run a dedicated ground to the battery and use it for your meter ground.
Verify your meter will show steady voltage at alternator and battery terminal.
Use alligator clamps to hold the meter probes to the wires, no wiggling around.

Cheap old meters have ****py leads and probes, Harbor Freight sells decent meters for cheap, go easy on the wires and it should work long enough to diagnose your problem.

 

Joe,
The digital meter im using is an older cheapie. That being said, it shows solid 14 volts all through the circuit from the alternator, to the positve terminal on the firewall, to the ignition switch to the fuse panel and at the terminal out of the panel, but drops and fluctuates at the feed to the resistor. It duplicates this result with a new jumper wire as well. I used the intake manifold as the ground to test the ballast lead and also the aluminum dash,
(Where i tested the switch and panel voltage on the circuit).
I may try a dedicated ground from the battery as you suggest. And try a different meter as well.

 

Sometimes a light bulb is better than a meter. It reacts a bit slow as it takes time for the filament to change temperature, but wildly fluctuating voltage will give fluctuating light too.

 

I was thinking maybe the block is loosing ground intermittently, thats why the battery post is a better location to test from.

I was working on a school bus a few weeks ago with a no start issue, turned out power to transmission wasn't right, so the engine wouldn't start not knowing what gear the trans was in. Volt meter showed 12.9 battery voltage, LED test light was dim, about 8" up the wire it had corroded and had the green death all through it. A good tug pulled it apart. The meter showing battery voltage doesn't mean the wire is good, in my case I had no amperage.

 

JW,
I went back to study the specs of how i set up my ignition. I have a coil with approximately 1.5 ohms resistance and a
Resistor of 1.5 ohms adding up to 3 ohms resitance total. After reading some old posts, some folks refer to a 1.5 ohm coil as a 6 volt coil. So yes, i do infact have a "6volt" coil.

 

The coil should/could have some info stamped on the bottom. JW