Plug wire routing question

714Speed · 10-09-03, 10:45 PM

My 71 350 just got new plugs and I have new wires as well. My question is: Do I have to route the wires through the shielding on the bottom of the block? Is this shielding on the bottom of the block to protect radio frequency or is it a heat shield?

WhalePirot · 10-10-03, 01:00 AM

Shielding is for noise suppression from the rf noise emitted as the current passes through the wires, picked up by the radio, as the car is non-shielding fiberglass. The shields should have grounding straps, too.

Jack · 10-10-03, 08:35 PM

Quote:

Originally posted by 714Speed
My 71 350 just got new plugs and I have new wires as well. My question is: Do I have to route the wires through the shielding on the bottom of the block? Is this shielding on the bottom of the block to protect radio frequency or is it a heat shield?

If you use wires that have a spiral or helically wound core you do not need to use the shields ... shields are for RF suppression.
JACK

714Speed · 10-10-03, 09:55 PM

Jack: I bought the replacement AC Delco 7mm's from the local parts store. $27.00 I'll go see if they are what you described. Without jack stands it's near impossible to disassemble the lower shielding, maybe impossible. Thanks. NH

714Speed · 10-11-03, 09:26 AM

FYI: I checked the AC Delco box and the wires are suppose to be engineered to eliminate radio frequency interference. I can get to the shielding on the driver's side block, so I'll definately route the wires through on that side. But the starter and motor mounts on the pass side make it near impossible to do unless you have air tools and a real garage. If anyone with more experience thinks this would cause major problems please let me know. Learning, NH.

714Speed · 10-11-03, 08:02 PM

Great idea.....................2 hours too late, though. I have just re routed and very carefully kept the wires in the same proximity as the shielding. Radio works fine, too.

WhalePirot · 10-13-03, 01:34 AM

This has been true since they went to carbon-embedded, non-metal wires, decades ago. Problem solved in a steel car!

As an aside for you budget types, I have fixed a high-resistance-reading wire of this type by removing the spark plug boot and cutting about an inch from the wire. Then reattach the connector and boot. Seems the breakdown occurs, often, at that end when plugs are changed.

If you really want radio noise, change only the coil wire to a 'real wire' wire.