Don't forget to replace any ailing wire supports while you're at it. They are cheap, look good and prolong the life of the wires. Check out that one that dug a rut into your cam cover.

I change my wires about every 50K, in spite of no apparent problems.

When I got my '92 3 years ago, I was winding it out thru the gears and felt a miss at higher revs. I was afraid it was a bad valve in my new acquisition. I had already put in new plugs, cap and rotor, but the miss went away with a new set of wires. I checked the resistance on the old wires and although I can't recall the numbers, one plug wire was way out of line with the rest, even though they all looked good to the eye.

I have had several problem with wires over the years. One quick check is to run the car in the dark- as dark as you can make it. Have the hood open and watch for a light show- you can see the spark leak out to a metal component. If you can have someone rev the engine a bit, so much the better. Its not as scientific as a scope- but I have found several bad wires on cars that didn't seem to need them. If they are really bad, you can hear them as well. This wont account for any corrosion that may have formed on the end, or any wires that have failed internally - high resistance. If you want to be safe, I would replace them every 30K miles.

Mike

I recently replaced the original spark plug cables in our 83 at 155k mi. They still looked to be in good shape, but after 21 years I thought it was time. Absolutely no difference in performance/economy with the new wires installed, but hopefully they too will last a long time.

Son's 81 had been through a P.O. or two and had ratty looking cables and plug sockets...not Bougicord. I replaced them with some decent looking Bougicords from the pick 'n pull which cured a stumble when accelerating.

I'd say the Bougicords are good for 100k or so.
--
Bob (son's 81-244GL B21F, dtr's 83-244DL B23F, 'my' 94-944 B230FD; plus grocery-getter Dodge minivan, hobbycar 77 MGB, and numerous old motorcycles)

If the level of reliability is based on the oats you feed your horse, then why switch horses in the middle of the stream?