Engine: Why is my spark so weak.

[52-fan]

I spent the afternoon trying to get my 52 running. Some of you know that Lenard put a 259 in the car and he changed it to 12 volts. The wiring has been modified and I spent a good part of my time tracing wires and figuring out what had been done. I finally got power to the coil and I could get it to read on the negative terminal as long as the wires were not connected. When I hooked the wire to the distributor to the I got no reading on that side. After my brother came over I had him crank the engine while I watched the points and then checked the coil wire. The spark at the points was weak and the spark from the coil wire was blue, but very small. What am I missing?

[41 Frank]

You will not get a reading of any current on the _ side of the coil while the points are closed Howard.

[StudeRich]

If the spark is weak one possibility is; he did not install the Dual small terminal 12 Volt Solenoid, with the "IGN" Term wire going to the Coil (+) Term. and a "Start" type Ignition Switch with a Resistance Wire from the Ign. Sw. ALSO to the Coil (+) Term. or a resister at the Coil.
This 1956 to 1966 setup is required for all 12 Volt Cars.

Also check the Ground from the Dist. to the block, from right Engine Block Mounting BRACKET to the frame crossmember and Battery to Water Manifold.

As long as the Coil is 1.5 OHM for a V8, it does not matter about 6 or 12 Volt.

[christophe]

A weak spark at the points can also be caused by a bad condenser or a worn out wire that touches the distributor body. I'm referring to the ground wire going from the points to the coil.

[bezhawk]

Actually the points are not supposed to spark....that is why the condenser is there in the first place....to bypass the current to ground . A blue spark should be sufficient to run the vehicle. If you said a weak orange spark then you should be concerned. Look to timing, the point gap itself, the pig tail wire inside the distributor, and then your fuel system.

[DEEPNHOCK]

Actually the points are not supposed to spark....that is why the condenser is there in the first place....to bypass the current to ground . A blue spark should be sufficient to run the vehicle. If you said a weak orange spark then you should be concerned. Look to timing, the point gap itself, the pig tail wire inside the distributor, and then your fuel system.

You usually see the spark because you have the cap off, and you are looking at the points when it is on the cranking circuit (full 12 volts).
The spark is much less visible during when on the 'run' circuit (approx 7.5 volts)...
Remember that the circuit is just a path to ground.
When you interrupt the current flow to ground (points opening), the current seeks another path to ground
(which should be the secondary windings in the coil).
Anything that obstructs the normal path to ground will affect the circuit
(oily points, encrusted points, loose connection, wide spark plug gap, fouled spark plugs, bad spark plug wires,etc).

[52-fan]

I have not bothered with the fuel system yet because I saw that I was not getting a spark. Now I have a weak spark. The coil says on the side that it does not need an external resistor. (BTW The plug I pulled at first to see if I had a spark was a light tan and fairly clean. The engine must have been running pretty well before its storage.)
There are two wires off of the - coil terminal that go to the overdrive. Since he put a cable throttle on the car, there is a switch on the dash to allow the overdrive to engage. I checked the switch and it is hot on three terminals and the fourth is hot when the button is pushed in. It was sticking, but I loosened it up.
I am going to check the wires closer. I have found some less than craftsman like work which was maybe done for a temporary fix. The car will have to be rewired eventually.

[rstrasser]

I am joining this thread late so disregard my thoughts if they have already been tried.
I would disconnect all wires from the coil. Reconnect the wire from the distributor to the - side of the coil. Run a temporary wire from the + post on the battery to the + terminal on the coil. Then try to start the car.
I am not familiar with a coil that does not need a by pass wire. As the by pass wire is used to make the spark hotter while trying to start the engine due to the voltage drop that occurs to the coil when starting the engine. In any case; the condenser that is in the distributor has to match the coil. Say if the coil is from a 63 Ford then the capacitor should be the one that Ford specks for that coil.
Ron

[52-fan]

Thanks for the suggestions. I think I will pull the distributor and check all the connections and parts. I think some of the wires may benefit from some shrink tubing in place of the electrical tape and so forth. It's hard to believe the engine needs much to run. Lenard was driving the car before his illness.

[Dan Timberlake]

testing spark strength using a new plug with gap widened to 3/16 " or so can be telling.

[52-fan]

Well, I pulled the distributor and cleaned and set the points along with checking the wires and generally cleaning everything. I don't know what did the trick, but by pouring a bit of gas into the carburetor I got the engine to run. Tomorrow I hope to find out why gas is not getting to the carburetor.

[DEEPNHOCK]

Well, I pulled the distributor and cleaned and set the points along with checking the wires and generally cleaning everything. I don't know what did the trick, but by pouring a bit of gas into the carburetor I got the engine to run. Tomorrow I hope to find out why gas is not getting to the carburetor.

Couple of tips.
Setting the points does not mean they are set 'properly'.
The points are set to a point where the 'dwell' time is within the factory specification (28 to 32 degree's on a V8 engine).
The 'dwell time' is the amount of time, measured in degree's, that the points are 'open'.

For every two degree's you change the dwell time, you change the initial timing one degree.
So always do your tune up by setting the dwell first. Then set your timing.

Also. Dwell is affected by distributor cam lobe wear, point set rubbing block wear, and even point surface wear.
Use the proper 'point lube' on your rubbing block. This will slow down the rubbing block and cam wear.

As gap decreases - dwell increases.

So... (in my opinion based on experience).. The rubbing block is the real wear item on a point set.
So, as the block wears, the gap decreases and the dwell increases.
I always set my dwell first, and set it to the low number.
The feeler gauge is only used at first to start the engine and read the dwell meter.
Then, the dwell is set by adjusting the points to get the chosen dwell number.
So, as the rubbing block wears, the point gap will decrease, and the dwell number will grow.
Setting the gap to the low dwell number will help the tune up lasts longer.
HTIH (Hope The Info Helps)

[52-fan]

I have a dwell meter, but for today I was just trying to get the engine to run.