Re: Engine power

Posted by Bob Carabbio on August 03, 1997 at 09:37:10

In Reply to: Engine power
posted by Larry Jenkins on August 03, 1997 at 05:27:41

For a negative ground system -
The Battery wire (Whatever color) goes to the "+" terminal on the coil.
The wire that goes to the distributer through the Ignition switch goes to the "-" terminal.
The coil may or may not require a resistor depending on how it was made.If it needs a resistor, and you don't use one, it'll take out the points rapidly due to electrical overload, but in the short term it'll run just fine.The only way to find out about the specific unit you have would be to check with the manufacturer of the coil if possible.OR if you know what type of car it was for, find out if that car used a resistor.
For what it's worth, VW 12 volt coils (Beetle/bus 1967-75)don't use resistors.
backwards connection of the primary ("+" and "-")terminals will weaken the spark.
A weak spark typically will idle and run without load, but misfire under acceleration since when the cylinder pressure increases, more voltage is required to jump the gap. A weak spark also normally runs better with a richer mixture.
As a test, pull the plugs and close the gap down to 0.010 or so.If this makes the engine run better there's an indication of ignition problems.If it doesn't make any difference, fuel starvation or air leaks are more likely problems.
Some of the repro distributer bodies/caps are VERY leaky.I watched a spark jump through the body insulation from the #4 plug internal conductor to the #3 plug strap on a friend's car with a relatively new body.You may want to take a look at the engine running in the dark and see if there are sparks showing in places where they shouldn't.Sometimes the engine will be O.K. at idle, but the spark will jump somewhere else under power. the nose of the coil is a frequent problem spot since moisture runs down there and causes leakage paths.
Let us know what you find -
Bob Carabbio

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