Cap & Rotor

[BNielsen]

I've got a NAPA/Echlin cap and rotor on my truck; had an AC Delco cap/rotor for close to 50K miles. I had an Accel cap/rotor I put on the truck ahead of my camping trip last spring, and they were bad right out of the box, so the NAPA ones got thrown on and I haven't had a lick of trouble.
Since the truck's getting a new distributor soon I'm probably going with a DUI dizzy; I've already got their coil and ICM and it made a noticeable difference in the throttle response of the truck.

 

[Schurkey]

What cap and rotor are you guys liking? After a few fails with aftermarket C&R's I have stuck with AC Delco or OEM for a long time.

For what vehicle? Old coil-in-cap HEIs, I've been using Accel caps 'n' rotors. Inexpensive out of Summit at the time--I stocked-up.

TBI = any decent brand name. Doesn't seem to be critical. I sent-back an MSD cap because it was expensive...and Chinese.

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Vortec is the only distributor that seems to have common problems with caps. Those problems seem to be related to the way the conductors cross-over each other within the plastic body of the cap--the plastic insulation fails, and the spark goes where it's not supposed to. I don't know of any excess problems with rotors. I bought the vented United Motor Products cap and rotor set for my '97 well over a year ago, and still have not installed it. All I can say is that it LOOKS like a top-notch product.

For those that recommend the all copper caps,

So nobody has any miles on their copper caps?

MY concern about copper contacts is longevity. In the past copper contacts had noticably less lifespan than the factory aluminum contacts. Was wondering if anybody has ran 40k-50k with the Blue Streak or United copper caps, vented or unvented.

Brass, not copper.

Brass and bronze are both copper alloys. Brass is copper + zinc. Bronze is copper + tin. Neither one is a good conductor despite being mostly copper which is a wonderful conductor. Getting it "dirty" with zinc or tin destroys the conductivity. Aluminum is a much better conductor--but it corrodes readily inside a distributor cap.

The usual selling-point for brass terminals is that they don't corrode quickly--so it's really surprising to me that you're having trouble with them. For most folks they outlast aluminum contacts by about 3:1. How old are your plug wires?

I've got photos of a nasty Standard cap with brass terminals, but it's got a heap of miles on it...40K, maybe.

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I scraped all the ugly off the terminals, and put it back on the distributor. The rotor-to-terminal gap is a little bigger now, but I'm not worried.

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[alpinecrick]

Schurkey,
Brass, not copper. Brain fade. Not having trouble with them because all I have used for quite some time are ACD and one Delphi., In the past brass contacts on caps seemed to have a reputation of a shorter life.

My ACD plug wires have less than 30k on them.

At this juncture the only non Vortec V8 is my TD truck.

I think I'll try the United cap and rotor kit with brass contacts.

 

[Schurkey]

It's probably worth inspecting the plug wires using an ohmmeter. I've seen plug wires that the cylinder still ran (at idle and low load) with 100,000 ohms of resistance. Misfired under heavy throttle.

About the same for coil wires, only more obvious--it affects every cylinder, and it often burns the center carbon button on the distributor cap in the process.

"Carbon-rope" plug wires have ~2000 ohms per foot when new. Somewhat more than that after a few years. But even a 3-foot wire shouldn't have more than 15K ohms, and hopefully less. The helically-wound (sometimes called "spiral-wound") metal-conductor wires have far less resistance, and get a lot of advertising and media attention--but they're hiding the fact that they have tremendous inductance. Either resistance, or inductance, kills amperage/current flow in a plug wire. However, the metal-wound ones seem to have a longer service life in general.

 

[termite]

It's probably worth inspecting the plug wires using an ohmmeter. I've seen plug wires that the cylinder still ran (at idle and low load) with 100,000 ohms of resistance. Misfired under heavy throttle.

About the same for coil wires, only more obvious--it affects every cylinder, and it often burns the center carbon button on the distributor cap in the process.

"Carbon-rope" plug wires have ~2000 ohms per foot when new. Somewhat more than that after a few years. But even a 3-foot wire shouldn't have more than 15K ohms, and hopefully less. The helically-wound (sometimes called "spiral-wound") metal-conductor wires have far less resistance, and get a lot of advertising and media attention--but they're hiding the fact that they have tremendous inductance. Either resistance, or inductance, kills amperage/current flow in a plug wire. However, the metal-wound ones seem to have a longer service life in general.

Slight hijack, any special methods of testing plug and coil wires or just ohm them out with a decent meter if no obvious signs of damage or deterioration on casing?

 

[Erik the Awful]

On the darkest of nights fire up your truck and look under the hood to see if the spark plugs are arcing. If not, keep running them.

This assumes that you're not already fighting misfires.

 

[Scooterwrench]

I worked on a lot of inboard launch boat engines and Cadillac engines on airboats in the fishing community I used to live in. Aluminum terminals in caps didn't last very long and the brass terminal caps held up for years. Brass is all I will use now.

 

[Schurkey]

On the darkest of nights fire up your truck and look under the hood to see if the spark plugs are arcing. If not, keep running them.

Spark plug WIRES? That IS a valid test. But it's not the only way plug wires fail.

That, an inspection for cut or burnt insulation, and an ohmmeter test of the plug-wire resistance should all be done if problems are suspected.

 

[Schurkey]

any special methods of testing plug and coil wires or just ohm them out with a decent meter if no obvious signs of damage or deterioration on casing?

Nothing special. It helps to wiggle the wire being tested, while watching the meter. If the meter goes crazy, you may have an internal break in the conductor. Or, you might just have poor connection between the ends of the test leads, and the plug wire.

 

[name]

Six years and just over 50k miles ago I did a Cap, Rotor, Wires and plug replacement on my 1994 GMC Suburban, everything was bought from Summit racing:

1) The plugs are NKG R UR 5 V-Power
2) The Cap and Rotor were the "Blue Streak" set with brass terminals
3) The wires were the Summit brand 8mm Low Ohm .

This unit is mainly used at highway speeds ( 60 - 70 MPH ) with very little ideling or city driving. Also, when I checked the gap on the plugs I pulled, 4 of them were gaped at the factory setting of .043 ( straight out of the box ) and the other 4 were gaped at the under the hood sticker recommendation of .035. ( the best I can figure is I did one side by myself when I was paying attention and the other side when someone stopped by to bullshit ) but at any rate the side with the bigger gap had a lot more crusty deposits on the insulators and tip. the side that were gaped to the factory sticker look a lot better with hardly any deposits at all.

The cap and rotor looked like crap and I figure I am very lucky it did not leave me set in the middle of the road. When I pulled the coil wire off, it literally pulled the terminal off with it. There were a LOT of debris on the inside of the distributor and on top of the rotor.

The wires looked to be in great shape, and If I had not tore a couple of the boots with a pair of needle nose pliers trying to get them off, I would reuse them.



Here are the pictures so you can Judge for yourself :

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