35th Anniversary Thunderbird Registry

Changing Plugs and Wires


Well known SC'er, Vernon Cradier, was kind enough to share his experiences with plugs and wires from his years of experience in maintaining his SC.

With respect to plug wires,
"As for good stock appearing wires it's really simple, use the stock wires.
The Motorcraft wires are spiral wound solid core so you can't buy a better spark, just better insulation and I've yet to hear of anyone having spark leakage problems.  In the old days of carbon core RFI suppression wires, leakage or spark jumping was an issue.  With solid core wire, the spark usually gets where it needs to unless the wire is obviously damaged.  Since OEM is solid core nowadays, there's not much reason to switch, only price or appearance.  And if OEM is the appearance you're asking about, the higher price is necessary."

With respect to spark plugs,
"It's recommended that you use Motorcraft AWSF-32PP, or equivalent, gapped to around .047. These are double platinum plugs and will provide long service. "

When it comes to changing plugs on an SC, Vernon's method is very concise and easy to follow.

"The cylinders are numbered like so, facing engine from front of car.
Front to back, left hand side then right hand side.  #1 is the front passenger side and #3 is the rear. 
#4 is the front, driver's side, and #6 is the rear.

#1:  Done from up top, remove the air intake tube and put in trunk for safe keeping.  Drain and remove the coolant overflow bottle and put in trunk. Now you can get to #1 with a swivel on the spark plug socket and about two or three 3" extensions on the ratchet.

#2:  Done from under the passenger side.  Due to the tight fit, it is easier to use a short socket that fits on the hex head of the spark plug socket.  Push the spark-plug socket on by hand then slide on the ratchet with the short socket that fits the plug socket head to loosen and install.

#3:  Underneath, use a short  (3") extension on the ratchet with the plug socket.  It may be easier to push the socket and extension on first then put the ratchet on them.

Warning: I may have 2 and 3 mixed up in my memory but I don't think so. If you try and it seems like it then switch methods and see what happens.

4-5 from underneath driver's side

#4:  just socket and ratchet, fits and turns.  May have to put socket on first like others.

#5 & 6 are pretty easy.

Do make sure wires get centered then clicked down.  Don't try to crimp the terminal for tight fit on tip of plug, for any reason.

When installing, coat the threads of all plugs lightly with anti-seize compound. This stuff is messy so have a roll of blue towels handy.  If you get some on the tips, clean with carburetor brake cleaner and do over.  Tighten plugs until they just seat then just a bit more, don't strong-arm them.

When loosening if they are stiff, don't strong arm them, just maintain pressure and they usually break loose within 5-10 seconds. If not, then slightly increase pressure and try again.  The engine must be cold (aluminum threads, you know)." (additional note: this is something I see all the time. When you have a very tight bolt or fitting, the trick to getting it loose is to apply pressure SLOWLY. It will usually break loose as you increase torque. If you whip on it hard, you will almost certainly snap something. )

"If you drop a plug, inspect it BIG TIME.  If in doubt get another one--this is very important.  If you start it up and it's missing badly, then one is broken. Without a scope, it's a guessing game as to which one.  If this happens and you dropped one or heard some cracking sounds when torqueing one in, try replacing the plug(s) in question first. With fresh anti-seize you can do it warm, ....hot, you can't touch it!

Study the routing of the wires and only remove and replace one side at a time to avoid mix-ups.  Match the old wires to the same size wires in the new set.  Take each engine side of the plug wires off while still in the looms; there are three on each side.  Then match the wires to that side and lay them out next to the old ones, spaced exactly alike.  Then transfer the looms one at time to the new wires.  Start from coil ends to plug ends and put the three for that side back on in one piece.

Make sure that the new wires sit clear of any hot or moving parts when on."

Disclaimer: This information is for personal use only and for assisting owners in maintaining their vehicle. No publishing or reprinting is allowed unless by permission by the author of this article.