Even the world's finest ignition wires are at the mercy of two things:the ignition system and, of course, Mother Nature. As ignition powerbecomes stronger and spark-plug gaps increase, the chance of sparkleakage through the wire casing increases. In today's cars, severalissues are at play: High-powered ignition buzz boxes are common,particularly in performance applications. As a result, almost all wiresare susceptible to voltage leaks and crossfire (our apologies to '82 and'84 Corvette owners). Also, engine compartments are more and morecrowded.
This sleeve from Moroso (the...
This sleeve from Moroso (the company calls it "Blue Max") follows thetheory that the sleeve must be closely woven and further protected by alayer of silicone on the outer surface. This sleeve material is designedto seal the wire completely.
Because of these factors, there is less airflow around the spark-plugwires, and the added heat wreaks havoc on the wires. But there's more:Corvette enthusiasts are a serious bunch (or at least, we take our hobbyseriously). Many of us tend to push our equipment harder and, at thesame time, expect more out of that equipment. In simple terms, it'stough to tolerate something as "insignificant" as a set of bad wiresruining our fun.
The same applies to heat. Too much of it means the wires canself-destruct, usually at the most inopportune time.
This is a new sleeve configuration...
This is a new sleeve configuration from MSD. The design is similar tothe earlier woven-glass configuration, however, the exterior shellconsists of a special silicone-rubber coating. The inside diametermeasures 3/8 inch, which allows it to slide easily over most ignitionwires. MSD claims its Pro-Heat Guard has a core that can resisttemperatures up to 1,000 degrees F.
There's an answer to this dilemma: a spark-plug-wire sleeve. For theuninitiated, a sleeve is an add-on insulator that effectively protectsyour wires from the engine's high-heat environment and ignition system.There are a couple of schools of thought when it comes to wire sleeves.One maintains that a closely woven sleeve with a silicone outer jacketis best suited for the job. The other maintains that the sleeve shouldbe capable of breathing so it doesn't trap moisture between the wire andsleeve. In either case, the sleeves do their job.
Typically, sleeves can add 8,000 volts of extra insulation, add almostdouble that figure in crossfire "insurance," and offer a profoundresistance to heat created by headers or exhaust manifolds found intight engine compartments. Sound interesting? If so, check out thefollowing photos. We'll show you the process of installing the sleevesover a set of wires, and how to seal them to the spark-plug boots anddistributor- cap boots.
Since the sleeve isn't a tight...
Since the sleeve isn't a tight fit over the wire (generally speaking),some system of sealing the sleeve to the boot must be incorporated. Tosolve this problem, Moroso came up with a large-diameter "shrink sleeve"arrangement. The blue shrink material fits partway over the boot andextends partway over the sleeve, sealing the wire sleeve to the boot.
It's not a painful operation and it works.
Parts Department
Manufacturer/Description/Part Number
MSD/ Heat Guard wire sleeve kit/ 3408
MSD/ Shrink Sleeve kit/ 3409
MSD/ Pro-Heat Guard wire sleeve kit/ 3411
MSD/ Shrink Sleeve kit (Pro)/ 3407
Moroso/ Blue Max sleeve/ 72000
Moroso/ Blue Max shrink sleeve kit/ 72030
Moroso/ Blue Max numbered shrink sleeves/ 72020
 While this piece from Moroso...  While this piece from Moroso won't make your car any faster or morereliable, it will help organize things under the hood. This is a set ofgray-colored identifying shrink sleeves. Prenumbered 1 through 8, theseshrink sleeves are used to number the wires. |  In order to install the sleeves,...  In order to install the sleeves, one boot must be removed (it doesn'tmatter if it's on the distributor cap side or the spark plug side).Obviously, if you're changing the wires, this is the time to add thesleeves. Measure the wire, then measure a section of sleeve (it can beapproximately 1-1 1/2 inches shorter than the wire because the boots takeup some room on the wire). The sleeve material is easily cut to lengthwith a pair of sharp scissors. |  Slide the sleeve over the...  Slide the sleeve over the partially completed wire. Take your time. Insome cases, it's best to constantly massage the sleeve material so itdoesn't bunch up or kink. You can tie a knot in the end of the wire(sans insulation) and pull it through the sleeve, but we prefer togently slide it over the wire. Be sure to add two sections of shrinktubing before you reinstall the boot (you'll never get the shrink tubingover the boots). |
 Next, slide one of the shrink...  Next, slide one of the shrink sleeves over the end of the wire,positioning it over the boot and sleeve. While a match or lighter willshrink the sleeve, a heat gun is the best bet for "shrinking theshrink." An open flame, such as a match, will get the job done but, inmany cases, far too quickly. The result is often a heavily distorted orburned heat shrink. If you use a heat gun, simply apply heat and watchthe shrink do its thing. If any unsightly wrinkles are evident, applymore localized heat. Be forewarned: You can go too far with a shrink.When it looks right, stop! Too much heat will distort the shrink-sleevematerial. |  This close-up shows how the...  This close-up shows how the finished Moroso sleeves look after beingheated with the gun. Rest assured, they will be leak-proof and will passthe highest voltage possible to the spark plugs. |  In contrast, this is what...  In contrast, this is what the MSD package looks like when slipped over asection of wire. We've used both MSD and Moroso, and the difference is amatter of preference. |