Ignition problem

Ken/Alabama

Ken/Alabama

Well-known member
A friend has a 53 Flathead and it keeps burning up distributor caps . I suggested maybe wrong coil or wrong polarity and/or a high resistance in the plugs or wires . Any other thoghts on this ? Thanks
 
The 6-volt 8BA family of engines didn't have a real high output ignition system by any stretch of the imagination. There could be a quality issue with replacement parts. There is normally a certain amount of arcing that goes on in the cap but excessive arcing could be a problem with spark plugs, wires, or internal distributor parts or even the type of coil being used. Getting the high tension spark through the system depends on the resistance in the leads and the spark plug. Too much resistance tends to cause a little more arcing. Higher than stock compression ratios can also have an effect.

If the coil terminal polarity is switched to an off polarity situation, it usually weakens the spark by 20% or better.
 
Would too much "play" in the distributor shaft cause enough wobble to arc the rotor against the cap terminals?
 
George/Maine said:
If 6 volts and round coil stock could be wired backwards. you want points to pos grd.
Click to expand...

To make sure I understand it right, the + side of the coil goes to the dist. and the - side to the switch ? Right now its wired just the opposite and that might be the culprit. This is a stock 53 ,6 volt pos ground, iron heads.
 
Ken/Alabama said:
To make sure I understand it right, the + side of the coil goes to the dist. and the - side to the switch ? Right now its wired just the opposite and that might be the culprit. This is a stock 53 ,6 volt pos ground, iron heads.
Click to expand...


Here is a foolproof easy method that will confirm your connections.

R
 
Electrically, the primary/secondary coil windings are not positive or negative but it would be nice understand why coils are marked with "+" and "-". Check the gap between the rotor and cap against spec and if the ballast resistor is providing the correct voltage to the coil.
 
Ken/Alabama said:
To make sure I understand it right, the + side of the coil goes to the dist. and the - side to the switch ? Right now its wired just the opposite and that might be the culprit. This is a stock 53 ,6 volt pos ground, iron heads.
Click to expand...
I think you nailed it wired wrong.
Pos + to points with pos grd.
 
Yeah I know of the pencil trick from working on old motorcycles. The thing that's nice about the tester is that it has two seperate red and green lights for people who don't have the best of vision.
 
49-53 Fords do not use a ballast resistor, unless you converted to 12 volt, then you need one. some of the caps have aluminum contacts, I prefer the one with brass contacts. also there is a clip that holds the rotor on, it fits over the dist. shaft top, most have this but some early ones had a little slit on the top side of the shaft instead of the clip, you can spread the slit if you are very carefull, it doesn't take much....the rotor should fit snug. you might already know this. the caps usualy last quite a while.
 
Ok Ronnie I bite how do you use a " SHARP " wooden pencil to check Polarity.

I guess a " NEWBE " forever.

BILL W

P.S. please use Small words. LOL LOL
 
Even though the coil may be wired incorrectly, make sure you check out the distributor plug wires and plug gaps as Henry/Kokomo suggested above.
 
Thanks Ronnie

Never knew that . Now I have to use it real soon so it get's filed in the old brain.
I am also starting to make a printed copy in a 3 ring binder of all the little tricks
that help along the way.
BILL W
 
BILL WZOREK said:
Thanks Ronnie

Never knew that . Now I have to use it real soon so it get's filed in the old brain.
I am also starting to make a printed copy in a 3 ring binder of all the little tricks
that help along the way.
BILL W
Click to expand...
LOL,LOL Bill that trick with the pencil is as old as dirt surprized you didn't know that one. ken ct.
 
Ken are saying I am as " OLD " as dirt / or are you saying that the pencil is that old. lol
The only pencil trick I remember growing up was the one that young girls would do to see if they were ready for there 1st training bra. LOL--LOL

BILL W
 
Guys , been reading this one with some interest.
I cant imagine how a incorrect coil polarity would damage or burn up a distributor cap.
Incorrect polarity typically decreases the coils output by as much as 50% etc. However most cars ( properly tuned) would even notice the lack of coil output based on the reserve voltage level being high enough that its never used . (unless everything is just plain worn out)
A burnt distributor cap is a product of :
cheap or defective parts ( theres some cheap stuff out there!!)
higher than normal voltage
loose connectors
poor plug wires
very lean air fuel making the coil max out all the time etc.
secondary voltage on a flathead is usually 5,000 volts or less when properly set up and tuned.....
:eek::D
 
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