Spark plug lead resistance

[Sony2000]

The engine won't idle well, even with a timing light.
An old manual says the points should just start to open at TDC.
Coil wire has 5K ohms resistance as well as #3 and #4 cylinder lead.
Resistance on #2 is 16K ohms, and on #1 it is 0. This mix is probably the cause.
My question is if the coil wire has 0 resistance, is that better than 5K ohms?
I just picked up two leads for #1 and #2, that have 10K ohms resistance each.

[hanleyclifford]

If you have a timing light you don't need to consider the points opening issue at all. But the use of the timing light depends on the centrifugal advance weights returning to their "rest" at low rpm which you must achieve to use the light properly. Do you have TDC marked on the flywheel housing and perhaps a spot of white paint on the tip of the crankshaft roll pin? I'm not too sure about this one, but my guess is that if I'm the coil I'm wondering about all these different discharge rates to the cylinders...:confused:

[Sony2000]

TDC is marked on the pulley for the alternator. Timing light was on the #1 cylinder with 0 ohms, and the flashing light showed TDC 75% of the time and an advanced flash of light 25% of the time. RPM hovered around 700 to 900.
Previously I had cleaned and greased up the centrifugal weights, and sensed a little binding when rotating the distributor rotor, back and forth.
I'll put on leads that match in resistance for cylinder 1 and 2. If there isn't an improvement, then the problem could be in the advance mechanism.

[sastanley]

why don't you buy a new matched set of plug wires? :confused:

[Sony2000]

why don't you buy a new matched set of plug wires? :confused:
I'm not sure a matched set is that matched. Resistance is greater with length of the lead. So these leads should be all the same length!
The Atomic 4s came from the factory with copper core wires that had 0 resistance.:cool:

[hanleyclifford]

... the flashing light showed TDC 75% of the time and an advanced flash of light 25% of the time. RPM hovered around 700 to 900. 700 - 900 will not work. You have to get down to 400 - 500 in order to be sure that properly lubricated weights return to rest. Try using light machine oil on the weights; grease can "hang" up.

[Dave Neptune]

Sony, forget the resistance in old wires as they can have small gaps that will measure open and still fire a plug!!!! If your wires are indeed "bad" you could have a carbon trail in your cap, and that could be why your light is fluctuating! The resistance will be less in the cap than the wire so the spark gets off track in the distributor and builds it's own carbon highway over time.
It is always a good idea to replace all hi-tension parts when replacing wires so include a cap and rotor. Don't do anything else at the same time.

Dave Neptune :cool:

[Sony2000]

I ran the new lead setup and I like the results. The engines is no longer jittery but runs like a little bulldog. The new thicker oil 15W40 could be helping as well. I'll be putting aside the timing light to set the points manually, or with a 12V tester. Once she reached a decent temperature the engine still wanted to bog down and stall, unless I kept on at least 3/4 choke. Adjusting the mixture and the throttle would not lessen the need for choke. So off with the carb, to clean out those little gas passage ways.

[rrranch]

You don't use a timing light on these old engines. From the original manual that came with my farmall, which is the same procedure, you set the timing marks at top dead center, loosen the distributer clamp a bit so you can turn it, then remove number 1 spark plug wire from the plug and put a paper clip in the boot.

Put the paper clip near a head bolt of something else a spark can jump to and first retard the distributor a few degrees then turn it to advance until a spark jumps. THAT is timed at 0.

Running with a timing light is a whole lot different depending on the advance springs.
My farmall and my A4 run perfect after timing this way. FWIW, old VW's, all farmalls, and most other old engines set at 0 timing time this way. NOT with a light. I only use a light if the specs call for 0 at a certain rpm.

It is very important to lube the advance springs too. There is a small felt piece in the top of the distributor shaft. A couple times a year put 2-3 drops of 3 in 1 oil on it. That lubes the distributor bushing on all of them that I know of and on most of the ones I've rebuilt also the advance mechanism if the holes aren't plugged up with junk.

I don't think your plug wire readings are that bad either. try wiggling the distributor shaft. If you can wiggle it much it will do exactly what you say. Also a weak cylinder can and a few other things. Look at the shaft and oil it first though.

[hanleyclifford]

Certainly it is possible to time without a timing light and many do it successfully. Be careful not to leave the ignition on too long while going thru the procedure. However, only the use of a light can give you visual confirmation of your advance curve and maximum. Only the light can reveal "bounce" in the centrifugal advance, or other irregularities.

[Sony2000]

The carb was reinvestigated and improved. I did notice that Moyer could sell a carb gasket that fits both early and late models, instead of keeping two in stock.
New points were added and set with an ohm meter at TDC, and a break in the current. That lead fires later than two others.
The engine ran normally for the first time since I reveived it in a number of pieces. It could idle at 500 rpm, and needed 1/2 choke for for quite a while.
The next challenge are three water leaks. Weather to let them be, or not, that is the question?

[hanleyclifford]

Now that you have set initial timing at TDC, it only remains to check your advance curve and ensure that the timing max out at 17 degrees BTDC. In some applications it is efficient to be a little more aggressive by perhaps a few degrees (hence the argument for so-called "power timing").