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440roadrunner · 11-11-2007, 11:24 AM

Sixtysix, that's not necessarily true. I've seen several failed coils that "gave trouble."

My own 69 RR--started running worse and worse, and harder to start over a period of days and weeks. FINALLY one day just refused to start at all. Here was the coil, even leaking a little oil.

My friend's '65 Chevelle, started missing at high end--under load. Finally got a little more and a little more worse.

This problem could be a number of things, including a bad valve or other cylinder problem, a crack/ track/ wet/ dirty cap/ rotor, bad wire or wires, or wires "leaky" and crossed so that they are crossfireing.

You just need to methodically go through things

CAREFULLY examine the cap and rotor, and maybe just replace them if there's ANY question

Take an ohmeter an measure each plug wire. They should be "about" equal. As you hold the ohmeter leads, wiggle and shake the wires.

Examine the wires carefully for damage, heat, cracks, oil soaked, etc

Snap the rotor to see if the advance weights move easily and "snappy" on the springs--that the mechanism isn't gummed or rusted up.

From your description, it's hard to say--you say "it's not running right". THAT covers a lot of ground

You say "it might be out of time." Why do you think so? Was the distributor loose or did someone move it? Modern Mopars with electronic distributors just don't get out of time, unless something bad is happening, like a timing chain badly worn, or worse, the crap phenolic timing sprocket wearing and (gasp) jumping teeth

If you seem to have a mis, such as one or two cylinders, checking the compression is always a good move.

One thing to ALWAYS try if you suspect a miss at one or two cylinders is to try this:

Get the engine warmed and idling as smooth as possible. Hook up a tach, either your dash tach or a test tach/dwell.

Rig a test clip to a small screwriver or sharp awl. GENTLY work the boots off the distributer so you can get the wires out.

Using a plastic fuse puller tool, pull one wire at a time, and short the empty distributor terminal with your wire/screwdriver, to prevent the spark from cross firing.

Observe the sound of the engine, and the tach

If all cylinders are "good" the tach should drop the same rpm at each cylinder. A "dead" cylinder will be immediately apparrent--the tach won't drop much if at all, and you will hear the engine--won't change speed much.

Throwing parts at the thing isn't the way to go at this.

11-11-2007, 11:24 AM	#4 (permalink)
440roadrunner Senior Member Join Date: Nov 2007 Posts: 272	Sixtysix, that's not necessarily true. I've seen several failed coils that "gave trouble." My own 69 RR--started running worse and worse, and harder to start over a period of days and weeks. FINALLY one day just refused to start at all. Here was the coil, even leaking a little oil. My friend's '65 Chevelle, started missing at high end--under load. Finally got a little more and a little more worse. This problem could be a number of things, including a bad valve or other cylinder problem, a crack/ track/ wet/ dirty cap/ rotor, bad wire or wires, or wires "leaky" and crossed so that they are crossfireing. You just need to methodically go through things CAREFULLY examine the cap and rotor, and maybe just replace them if there's ANY question Take an ohmeter an measure each plug wire. They should be "about" equal. As you hold the ohmeter leads, wiggle and shake the wires. Examine the wires carefully for damage, heat, cracks, oil soaked, etc Snap the rotor to see if the advance weights move easily and "snappy" on the springs--that the mechanism isn't gummed or rusted up. From your description, it's hard to say--you say "it's not running right". THAT covers a lot of ground You say "it might be out of time." Why do you think so? Was the distributor loose or did someone move it? Modern Mopars with electronic distributors just don't get out of time, unless something bad is happening, like a timing chain badly worn, or worse, the crap phenolic timing sprocket wearing and (gasp) jumping teeth If you seem to have a mis, such as one or two cylinders, checking the compression is always a good move. One thing to ALWAYS try if you suspect a miss at one or two cylinders is to try this: Get the engine warmed and idling as smooth as possible. Hook up a tach, either your dash tach or a test tach/dwell. Rig a test clip to a small screwriver or sharp awl. GENTLY work the boots off the distributer so you can get the wires out. Using a plastic fuse puller tool, pull one wire at a time, and short the empty distributor terminal with your wire/screwdriver, to prevent the spark from cross firing. Observe the sound of the engine, and the tach If all cylinders are "good" the tach should drop the same rpm at each cylinder. A "dead" cylinder will be immediately apparrent--the tach won't drop much if at all, and you will hear the engine--won't change speed much. Throwing parts at the thing isn't the way to go at this.