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Plug Wire Head Scratcher

co5j

Member
Joined
Jul 15, 2025
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Location
Coastal NC
70 Challenger 440 6-pack, having issues with plug wires popping off plugs while driving and just hanging loose. Noticed number 6 hanging and burned against exhaust manifold when we got the car from my father in laws house last year. Bought a new set of Moroso wires, routed them properly and installed thermal boots at the plugs as well. #6 has continued to pop off and today #8 was hanging when we got home. Plug ends are 90° and they feel like they clip when pushed on. Any suggestions? Would straight ends be better?
 
headers or factory exhaust manifolds? the boots can get pretty warm, and expand when hot. some of those plugs are protected by tiny heat shields. are those still present on your #6 and #8 spark plugs? I think the straight boots hold better, if you have the space to make them fit.

a wire (with plugs) head scratcher
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Manifolds, no headers. I dont believe the heat shields are present, thats thecreason i opted for the boot sleeves.
 
What plugs are you using , just wondering the plug tips are smaller than normal , I hve not seen this problem in the past .
Try new Champion or Autolite plugs
 
Brand new Champions, installed with the Moroso wire set. Any opinions on wire sets? Are some brands just better made or everything pretty much equal?
 
I used MSD mostly , Firecore is good also .
There is a huge difference in quality , Core quality & thickness , the ends also , insulation quality & thickness
 
If you're comfortable making your own spark plug wires, you can get a set of Rajah terminals for the sparkplug end. Below is a link to a set from Speedway Motors. They won't come off easily! I have a set of sparkplug wires for my big block Mopar that uses Packard 440 wires and Rajah terminals! Packard 440 is steel wire in a neoprene coating. Let's just say the AM radio is just static with these wires! But seriously, give the Rajah terminals a try!

 
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