Sounds stupid but......

Dobalovr

Dobalovr

Being on the Cbody diet SUCKS!
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OK new thread from me with what may sound stupid but has been bugging me about my beloved C Bodies....

Why does my #8 spark plug wire keep blowing off after a few hard acceleration passes at the plug? I have checked contacts tightened them pushed it on as far as it will go etc. The damn wire falls off the plug after about 5-6 accelerations. Lots of slack for movement and I ran the wire down the cover to the back of the head like it is supposed to be. I just don't get it. If you have a similar problem or the solution please let me know....my hand is scarred from trying to put hot wires back on around an even hotter manifold....

I will continue to post stupid questions to this thread as they arise so please forgive my ignorance sometimes....

Please feel free to post other stupid questions (I know there are no stupid questions) as you may answer one of mine indirectly :)
 
Dobalovr said:
OK new thread from me with what may sound stupid but has been bugging me about my beloved C Bodies....

Why does my #8 spark plug wire keep blowing off after a few hard acceleration passes at the plug? I have checked contacts tightened them pushed it on as far as it will go etc. The damn wire falls off the plug after about 5-6 accelerations. Lots of slack for movement and I ran the wire down the cover to the back of the head like it is supposed to be. I just don't get it. If you have a similar problem or the solution please let me know....my hand is scarred from trying to put hot wires back on around an even hotter manifold....

I will continue to post stupid questions to this thread as they arise so please forgive my ignorance sometimes....

Please feel free to post other stupid questions (I know there are no stupid questions) as you may answer one of mine indirectly :)
Click to expand...
I'll see your stupid question and raise you... did you by chance use dielectric grease in the boot?
If not, try this anyhow... a little brake clean in the boot and some on the plug... the boot may grip better afterwards. Never know what joys a greasy fingerprint may bring...
 
cantflip said:
I'll see your stupid question and raise you... did you by chance use dielectric grease in the boot?
If not, try this anyhow... a little brake clean in the boot and some on the plug... the boot may grip better afterwards. Never know what joys a greasy fingerprint may bring...
Click to expand...

No dielectric grease and it is a brand new plug and wire but that said greasy fingerprint....I wouldn't doubt it
 
A wrap with safety wire where the clip fits over the plug will help. Just tight enough to be able to snap the connector onto the plug. Something we used to do with all plug boots on the Stock Cars.
 
bluefury361 said:
A wrap with safety wire where the clip fits over the plug will help. Just tight enough to be able to snap the connector onto the plug. Something we used to do with all plug boots on the Stock Cars.
Click to expand...

SO what you are saying is this is not an unheard of situation? I have to say I have never run into it before. It is an angled boot and feels tight when it is on but it pulls off on its own accord....exhaust manifold valve linkage catching on it maybe?
 
Dobalovr said:
Now that makes sense to me. If there is a crack or leak it would build pressure up and blow the plug wire off....OK plug coming out stay tuned.
Click to expand...
Had the same problem once. Same plug over and over. Found the boot was too deep (don't know why) and the terminal wasn't fully being clipped onto the plug. Had to trim boot.
Yet another strange gremlin that defies logic and makes you say wtf...
 
commando1 said:
Had the same problem once. Same plug over and over. Found the boot was too deep (don't know why) and the terminal wasn't fully being clipped onto the plug. Had to trim boot.
Yet another strange gremlin that defies logic and makes you say wtf...
Click to expand...

This is why I changed plug wires albeit from the same manufacturer just in case the boot/clip wasn't making full contact. I am not a fan of angled boot plug wires at the best of times. I will double check both that and replace the plug like Big John suggested.
 
Dobalovr said:
Now that makes sense to me. If there is a crack or leak it would build pressure up and blow the plug wire off....OK plug coming out stay tuned.
Click to expand...
That's not impossible, but rare for sure... I would expect any pressure to want to let itself out past the boot/wire. I have had problems with poorly made boots on center plug heads (hemi, but wrong brand), they usually seal the tube and have a vent that I have had to trim open... then it was heat expansion that caused it.

It is not uncommon to find a small witness mark from gasses getting around the porcelain seal at the the metal threaded body... but if you had any significant pressure it would be a very loud "backfire like" sound... like a loose spark plug just before it launches (I have been around more than a few novices).
commando1 said:
Had the same problem once. Same plug over and over. Found the boot was too deep (don't know why) and the terminal wasn't fully being clipped onto the plug. Had to trim boot.
Yet another strange gremlin that defies logic and makes you say wtf...
Click to expand...
MrMoparCHP said:
I have found that the clip in the boot sometimes needs reshaped.

Alan
Click to expand...
I make it a practice to push the wire into the boot deep enough that the clip will make contact, then the boot will need to be fully seated (push/slide another 1/2 inch or so). This often requires the contact to be tweaked slightly... and lots are not aligned well when new.

Sorry no racing experience. but the safety wire trick makes sense and I do recall seeing it somewhere, I never had a need for safety wire or the special pliers... but I respect their importance in racing/aviation.
 
Big_John said:
I had this happen with my old Ford Exploder.

Click to expand...
bluefury361 said:
Yikes...... Looks like that plug was overdue for replacement anyways......
Click to expand...
Been there done that... Dad bough a used 1980(81?) f100 from a friend... three on the tree, power nothing and a 3.8 v6 strippy special. About 1994 I had to remove the original plugs all of which twisted the hex right off... wound up extracting them with a big fluted extractor and twisting a new tap holder... they were the worst I have seen and made that mess look nice.

But it would have to leak out the electrode to blow the boot off, if then...
 
bluefury361 said:
Yikes...... Looks like that plug was overdue for replacement anyways......
Click to expand...
Yea, that was a cheap beater that my son and I shared. It ran great, so like any good beater, I never laid a wrench to it unless I had to, but I think that one looks really bad because it had leaked.

Changing the plugs in that thing was a PITA!
 
commando1 said:
The industry needs to bring back the Flathead. Seriously.
K.I.S.S.
Click to expand...
The best way I could figure to change one of the plugs was to go in through a small opening in the fenderwell. I decided not to pull the tire, and instead I just added another long extension and stood next to the vehicle with the ratchet.
 
I had same thing happen to me on two plugs over and over again. Most rear plugs on both sides. What made it worse was my engine would stall when the wire comes off (don`t know why, but if I pull ANY single wire off the plug it stalls). I have found that it is way too hot for those wires (I got no heat shields on manifolds) and the air between the plug and rubber boot expands and pushes the boot off. After installing flexible fiberglass heat sleeves over the wires - problem is gone.
 
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