No Spark

01aford

01aford

Senior Member
My 1940 expert and friend, Bill Clatterbaugh, passed away in 2013 and I am in need of advice.
My 1940 Ford is original with the A block 85hp. Because of family priorities it was 10 months since it was last run. I drained the oil as well a emptying the gas tank.
I put fresh gas in and drove it about 30 miles. It ran well.
The next day I drove it again and it started running very poor. I made it home and it felt like it was not getting fuel or the coil/condenser was bad.
I started with the fuel and the pump as well as the carburetor were in good shape.
Next I went to the spark, while cold, I got no spark at the plugs.
I swapped out the coil with a rebuilt Skip coil as well as a nos condenser.
No spark or sporadic spark. I procured a new condenser from NAPA and still sporadic spark.
There is weak spark to the coil but certainly not snapping.
Additionally upon testing at one point I was getting spark at the plugs and the car started but ran very poor.
I checked the points and they are clean and properly gapped (helmet distributor).
The resister under the dash is intacted and does not appear to be be burnt out.
Could this be a solenoid issue?
I have no spark now.
To sum it up, I have replaced condensers, two Skip coils, checked and cleaned points which are not burnt and checked for loose wiring.
Any ideas?
I should note my battery is very weak at this point but is on the 6 volt high start charge when I am turning over the engine.
Thanks.
 
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If your battery is low it is possible there is not enough voltage left to fire the coil while cranking. Get it cranking up to speed and check it for spark.
 
On the charger im putting out 6.8 volts at the battery terminals.
But that’s an excellent point because it goes down very fast.
 
Another point is that it’s an older optima red top battery.
Any thoughts if this could be the issue?
 
Take the battery to an auto parts store and have it "load tested". They usually do it for free and that would diagnose it's condition and eliminate that potential gremlin. Chap
 
chap52 said:
Take the battery to an auto parts store and have it "load tested". They usually do it for free and that would diagnose it's condition and eliminate that potential gremlin. Chap
Click to expand...

I took the battery to advance and battery plus for a load test.
Both said the battery was fine and fully charged.
When I put it back in the car the starter winds down like the battery is dead.
Any ideas. All the wires are new and correct. I’ve checked the contacts.
Could the starter be the culprit in this issue.?
 
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01aford said:
I took the battery to advance and battery plus for a load test.
Both said the battery was fine and fully charged.
When I put it back in the car the starter winds down like the battery is dead.
Any ideas. All the wires are new and correct. I’ve checked the contacts.
Could the starter be the culprit in this issue.?
Click to expand...

It could still be the battery. If they load tested it with one of those hand held battery checkers like Autozone uses they are a joke. There is no way they can apply a large enough load on the battery. You need half the cold cranking amperage rating of the battery applied for 15-seconds. Then wait 15-seconds and perform the test again. That would melt one of those hand held tester's to the guy's hand. You need a real battery tester like a Sun Vat 40. I argued with the kid at the parts store that my battery would not hold a charge over night with no cables hooked to it so there was no possible draw on it. I told him there was no way his handheld tester could properly test it. He tested it with his hand held tester and it said it was good. I gave up arguing with him. The battery was under warranty and they should have replace it. I bought a new battery (at another store) and the problem was solved as I knew it would be. Those guys are not mechanics, all they know is green light good red light bad. A sixteen year old kid was arguing with a double ASE (light and heavy) Master Mechanic with 40-year's experience.

You really need a voltmeter so you can check the battery before cranking and then during cranking. If the voltage is dropping off too much it is either the battery or an excessive current draw from the starter pulling the voltage down. Excessive current would be either a bad starter or a tight engine. With the proper tester you can see the voltage reading and you can see starter's amperage draw.

Do not crank the engine for more than 15-seconds. Then let the starter cool down for 15-seconds before you crank it again. Otherwise the armature will get so hot it will melt the solder right out of it. That is what destroys starters. That's any starter on a engine, not just flatheads.

Here is the manual to the Vat 40 tester. It will give you an idea of how a "proper" load test is performed. I have two of these machines I purchased from a friend's families shop that was going out of business after nearly fifty-year's I business. You can still do some testing without one of these machines. You can put a voltmeter on the battery and crank the engine. The starter will "probably draw close to the equivalent load that you would apply with the Vat 40. I've only ever tested 12V batteries at work and at home so I know what the good reading are during a load test on a 12V battery. I didn't have a clue on a 6V battery? According to page 8 of this manual a 6V battery should not drop below 5V during a load test. See what reading you get with the ignition disabled while cranking the engine. You can go buy a cheap digital voltmeter for checking the voltage.

https://archive.org/details/SUNVAT40Ops1979/page/n9


If your battery reading is not dropping below specification while cranking then the starter could be bad. A starter can go bad and draw too many amps or go bad and not draw enough amps. If it was cranking slow and the voltage dropped off fast the starter could be drawing too many amps but the battery could also be bad too. If the starter is cranking slowly and the voltage is not dropping below specs the battery is probably good and either the starter is bad or you have excessive resistance in the battery cables or connections that is preventing enough amperage to flow to spin the starter.

Next, take some battery jumper cables and bypass each battery cable one at at time. Just connect the jumper cable to each end of the same battery cable. If the cable is bad then the current will bypass the battery cable and flow through the jumper cable and it should crank.

You want "good" jumper cables, not those those small diameter cables stores sell. Especially on a 6V system. A 6V battery requires twice the amperage flow to do the same amount of work as a 12V battery. That is why 6V battery cables need to be larger than 12V cables.

Next, if you have a volt meter you can do a "voltage drop test" to locate any resistance in the circuit that would cause the starter to turn slowly. Its really easy to do. There are plenty of Youtube videos that will show you how to do the test. You need to find a video that explains how the test works so you understand what is going on. Everybody needs a digital voltmeter, without one your just guessing at what's wrong. Buy one for yourself for Fathers Day. You need to be careful, cheap ones will work just fine on old cars but they can damage computers on new cars. Use a high impedance testing device with at least 10 megohm (10 million ohms of internal impedance) of impedance. This provides a very low load to the circuit being tested. This protects sensitive computer circuits from the overload that can be caused by a standard test light or meter.
 
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Ok.
I thought that the 30 second test wasn’t enough.
I’ll test it out tomorrow.
Thanks for the info.
I went to my old Napa store today. They replaced the old tester with a hand held too.
 
old school trick put a voltage gauge on the battery and use the starter to load test it often starters on their last legs draw excessive current and heat up dramatically watch how quickly the battery recovers its voltage when you stop cranking that will tell you how good the battery is and the state of the starter
 
I had a similar problem with my ‘34. I use an Altima battery also. After months of wrangling with with the system, I cleaned the battery posts and the cable ends with one of those bottle brushes. I also replaced a bolt on the cable end because I was having trouble getting it tight on the post.

Richard
 
“ I drained the oil as well a emptying the gas tank.
I put fresh gas in and drove it about 30 miles. It ran well.“ I’m not trying to be a smart ***, but you did fill it with oil too right?......”Additionally upon testing at one point I was getting spark at the plugs and the car started but ran very poor.”.....if the battery and starter can get the engine running, and it still runs poorly, I think there is still a fuel/spark issue....Mark
 
I was able to get back to it today.
The battery maintained a consistent voltage of 6.3 volts while being cranked.
All grounds rechecked. Which improved the sluggish starter situation.
I placed a bridge wire on the resister under the dash. Still no spark at the plugs and a very weak spark at the coil terminal. I basically had to touch the terminal with the wire to see the spark. Certainly the spark is jumping and distance on to the coil terminal.
Any ideas or thoughts will be appreciated.

Thanks.
 
I have several plugs removed and using the solenoid button to test.
No snapping hot spark at the plugs but when I was grounding the plug I got zapped pretty hard.
Some current is going to the plugs. My finger,hand and arm are still numb.
 
01aford said:
Thanks for the reply.
A wire from the + side or - side of the battery?
It’s a positive ground system.
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The power side to the coil is the same source that powers the rest of the car. The (+) terminal of the battery goes to ground, that is why it is called positive ground. Anything that requires power is from the (-) battery terminal, including the ignition (coil). Best source for a jumper is from the starter solenoid, but you have to make sure you connect to the battery side and not the starter cable side.
 
This side?
I just don’t want to make a mistake here so I’m double checking.
 

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