Probably a issue with a lot of us running headers that are touching or too close to the plug wires . Had to end a car cruise Fri. due to a stumbling engine . Got home ,got the multimeter out ,did a resistance check on ( fairly new quality) plug wires 2 were bad . Yes, when assembling tried different wire routes to avoid getting too close. This time there were a few wires that were actually touching Question s , what ,s a very good plug wire to stand up to heat from the headers.? also, have any of you ever used spark plug boot sleeves over the ends that guard against the heat from the exhaust headers ?. Do they help ? Thx much Gene in MN
Gene, Please post some photos along with year and make of engine and what type of vehicle. You may have to redesign your plug wiring routing.
Plug wire insulation sleeves are very effective, the best ones are slip on when you make plug wires. If you buy pre-made the sleeves are bigger. Not a big deal on closed hood engine compartment. Good routing or looms with zip ties works, need to ensure the wires stay separated. But still route where needed. I tried multiple things with angle plug heads and large tube headers on a SBC. The insulated wrap worked best. Plug wire life will just be shorter with headers / hi po engine / powerful ignition than stock vehicle.
What a straight boot and a 90-degree boot don't seem to naturally put a wire where I'd like it, I often find a 45-degree (or 135?) helps a lot. If you've let them touch the header, your routing needs work. Start there. Beyond that, those ceramic fiber wraps can help lengthen the lifetime of the wires, or something with low emissivity (shiny stuff) to block radiant heat transfer. Or, just swap in a nailhead and never worry about routing again!
I like to use the old fashioned wire routing that Chevy used on the small blocks, when they had the rams horn style manifolds, when using headers. The wires go down behind the heads, along the oil pan rail, up behind the motor mount, and to the plugs. You can get the parts to hold the wires in the correct place from places that sell reproduction parts. Also note that Corvettes used this routing with the HEI in the late 70s, so you can get the stuff to use 8mm wires if you want to.
I have found using these wire holders that attach to the lower valve cover bolts to be great. On headers, straight or angle plugs, ram's horn or under manifolds. I use two sets of wires to make one set of perfect length spark plug wires. Here's a couple of pictures. ..
I have a OT big block mopar that uses 45° ends on all but two plugs because they just don't clear the headers. Sometimes you gotta do what you gotta do.
I make my own wires with the products from MSG. In my '46 Ford Woodie, with a small block and Sanderson CC-4 headers, I use a combination of 90 degree and straight boots depending the location. I also use the sleeves on all the boots. 25,000 miles with zero problems.
I used Pertronix stock-look wires and shortened them to fit. With Sanderson block huggers they don't seem to be adversely affected. Now my Austin had a much tighter situation so after toasting the first set I used some "socks" from Summit. Again, Pertronix stock-look wires and no problems with the socks, and they get mighty hot. Sorry, didn't have a better picture
Jim beat me to it. I've used Corvette wire sets on several small blocks with headers after I went though the same thing you are running into. Far cleaner and uncluttered look to boot. If you have never installed a set that way the front two wires on each side are routed between the block and the motor mount. Every Chevy with Ram Horn Manifolds was wired that way from the factory.
If you look at Bob's post number 5, I have a similar set up, except with my heads it was better for me to use the straight boots on the first and last plug on each side. If I tried to use 90 degree it was very tight and close to the header. I also use the "socks" like pictured on the motor with the blower.
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