1973 F350 Super Camper Special 390V8

I can't figure out my plugs keep coming loose. After two-three weeks of normal driving the plugs are finger tight. If anyone can give me a answer I would really appreciate it.
Thanks, Barry

 

Are you torqueing them correctly? Are you sure they are the right plugs?

 

Have had that issue in the past as well. I thought i didn't install them tight after replacing the heads. Tightened with a torque wrench and had them come loose again. Got smart and did a 460 swap after that. For
some reason FE motors hate me.

 

I thought that the washers on spark plugs got crushed when first installed (as designed). After you seat them once and remove them aren't they prone to get loose? Or is that urban legend?

 

I don't remember a crush washer on my 390. If
I remember right it has the conical seat spark plugs.

 

I am having the same problem. Using torque wrench and conical seat spark plugs and less than a week my plugs are loose. Not good.

 

FE engines use 18mm tapered seat spark plugs, they don't use a washer.
I've had the same issue in the past and never have had a good answer as to what to do. I torque them and, on occasion, I'll check them.
Making sure the threads and tapered seat are clean seems to help along with using anti-seize on the threads. The anti-seize makes sure your getting full torque.

 

When I was running FE's. I was using anti seize, and a torque wrench as well. I still had the loose spark plug issue. Like I said before. FE's hate me.

 

You're not alone, I love 'em but they hate me too .

 

Excess carbon build-up on the plug seats not allowing them to fully seat??? iirc there's a specialty tool that threads into the plug hole and cleans the seat of carbon.

Ill-fitting socket giving the impression the plugs are tight??? most sockets don't properly fit the FE heads and bind up making it seem as the plugs are tight, even some of the so called 'thin walled' sockets can be too thick, take a cheap socket and grind a bevel into the bottom edge and use that.

 

Red locktight.. that'll keep em in there

 

FE's seem to have either plugs that won't stay tight, or they are so tight it takes a 5' cheater bar to break them loose. I can't explain why, just seems to be one extreme or the other.....

 

That's my typical experience with FE plugs, too tight (yes, i use anti-seize), loose plugs have never been an issue for me.