Refurbishing your spark plug boots

[stormcrow]

Several years ago I replaced my old spark plug wires with new OEM braided. Recently - I say recently - for about a year I have been having problems with the engine missing.

Although the P-car ran OK it was annoying - so I decided it was time to find out what was going on.

After doing extensive research I decided to pull the distributor and check it out. What I found was a lot of crud and worn shims. Completely cleaned the internals installed new shims, cleaned and lubed the advance mechanism and put everything back together.

What a surprise when I first fired up the P-car. Lots more power runs like a scalded dog. However, I still had an annoying miss at idle. The tach no longer jumps like it did prior to the cleaning and refurbishing.

I then checked the spark plug wires and found that I couldn't get readings on several of the spark plug boots. Well I didn't want to spend another $200 for plug wires just because the boots were the problem so I decided to do some investigating to see what the problem was.

I took one apart using a Dremmel a nd what I found was the following:

Inside the boot coming from the lug on the top is a brass rod, below the rod is three resistors. When I checked them for resistance I didn't get a reading.

Well I figured I could repair these without having to spend $45.00 each to replace them. So here's what I did -

I drilled a hole in the top of the Lug, inserted a brass rod that goes the full length of the boot minus the little spring. I then purchased #04 brass screws, cut the head off and soldered the screw and top lug to the brass rod. Walla - I now have a boot that has continuity.

Below is a picture of how I did the repair. I purchased the rod from the local hobby shop - 36" for $2.00 and the screws I purchased from the local HD store for $4.50 Picked up JB weld epoxy - that has a temp rating of 500 degrees.

Now there is other info on the site on how to do the same thing I did but the way I did mine was a little different - and they will work.

The picture shows the original internals with the resistors, next is the lay out of how the hole was drilled in lug and the screw, next shows everything completely soldered up - low temp silver solder - and lastly shows the completed boot minus the top rubber cover.

Prior to inserting the rod I put some epoxy on the shaft and pushed it in place. I then epoxied the top completely to ensure a good bond.

I will be installing the boots tomorrow after the epoxy sets up for around 12 hours. I also purchased new 8mm plug solid core wires - even though I probably don't need to but I figured if I was going to do the Boots I might as well do the wires.

I will post an update on the wire and boots when they are completed.

[Trackrash]

So no resisters? What are the resisters for? Radio static suppression? Will the spark be affected without them?

[stormcrow]

Gordon

I have done extensive research regarding using resistance on plug wires and always get different answers. Some say resistance can provide a larger spark, some say it's because of noise suppression and others say that you don't need resistance of any kind.

My Beru spark plug boots have deteriorated where I don't get any reading through them at all.

So what I am going to do is install these boots mainly because I have been having problems with the engine missing - even after the distributor refurbishing.

Now the way I see it is if I do need to add resistance I can purchase plugs with resistance already built into the plug. But if I don't then it won't matter one way or the other unless of course, I get a lot of noise in my radio or something else happens.

I guess the real question is is the CDI on my 78 911 SC designed so that there has to be a certain amount of resistance in the circuit. No one has addressed that issue as far as I can tell.

However, I would think taking a load off the CDI unit by not using resistance in the circuit could be a good thing - less of a load on it, less heat on the resistors, capicators and transistors to produce the spark.

[TCracingCA]

Could just buy two VW wire sets and that would leave you guys with two extra ones as spares that might fit later!

[The cap'n]

You, and the people driving next to you, are likely to experience a LOT of RF noise, IIRC. Looks like your spark will degrade, as well (as in "be weaker"). See this discussion from a while back:

spark plug wire resistance

Good luck with that. The Cap'n

[Discseven]

Nice dissection Stormcrow.

[stormcrow]

Here's an update on the Plug boot refurbishing.

The following pictures pretty much explain what I did.

Using the existing braided wire, I cut the insulation off the wire and exposed about 3/4 inch of bare wire and silver soldered it. I then took a yellow butt connector cut one end off and drilled out the little tabs in the center.

NOTE: Make sure you ohm check your wires to make sure there is continuity through them - Mine read around 43 ohms +/_

Using the existing wire, I cut off part of the heat shrink tubing to where the braid ends. That way you won't have to worry about the braid becoming unraveled.

Next I slipped over two pieces of heat shrink tubing. One being just large enough to fit over the braid and the other one large enough to fit over the end of the rubber boot.

I then worked the boot onto the wire with the end exposed about 1 1/2" which will give you enough wire to work with. Now you may need to spray some soapy water on the wire to get it through the boot.

Once I completed doing that I inserted the bare wire into one end of the boot making sure it was inserted into the sleeve - you may need to expand the sleeve on the butt connector a little so the wire insulation will fit inside it. Also make sure you have about an 1/8" of wire exposed on the other end.

While holding the wire securely into the butt connector I then screwed the screw on the boot into the other end. Once you start screwing the screw into the butt connector, the plug wire will remain in tact. You can also krimp the butt connector in the center to make a better connection.

Once that was completed smeared high temp RTV sealer around the butt connector where the wire was inserted - this will make a good seal. You should also apply some along the wire to better secure the wire.

Next take the smaller of the two heat shrink tubing and slide it over to the butt connector - also make sure the heat shrink tubing is long enough to cover the existing heat shrink tubing that secures the braid. Use a lighter to shrink the tubing.

Next add some more RTV sealer over the the ends of the rubber boot to make a good watertight connection - this will also prevent sparks from flying.

Slide the heat shrink tubing over the end of the boot - you need to make sure it's big enough to do this. Add heat to shrink it down and that's pretty much all there is to it.

Tomorrow will be test day and I will update the post.

Bare wire with silver solder on end



Boot installed over wire



Wire and Boot connected with Butt Connector



Rubber Boot installed



Heat Shrink Tubing over wire and braid



RTV Sealer



Final Product