Spark plug washer

[tbm3fan]

I was just outside pulling my plugs to re-gap them and I started to think about the washer on the end of the spark plug. I don't know why it dawned on my. Probably because I know Ford didn't use them for my cars but they were in use here. I don't know if that is correct. Google is useless and Google isn't all that smart since it thinks I want to buy speak plugs and ignores the other words.

So does a 1973 LA engine use the washers???

 

[Big_John]

Yes, it has a washer.

 

[tbm3fan]

Thanks, now to finish the job.

 

[stubs300]

But don't use them on /6's with drool tubes.

 

[CBODY67]

Generally, a "tapered seat" spark plug does not use washers. The spark plug seats in the head are also machined with a matching taper.

The plugs which use gaskets have a flat area above the threads, where the washer goes. The spark plug seat in the head is also at a 90 degree angle to the plug threads.

In some RARE cases, the spark plug seats are machined for BOTH types of plugs, but the plugs with the washers need to have them for effective sealing AND performance.

There were also "spark plug indexing washers", for both types of plugs, which are of variable thickness to have the spark plug ground electrode "aimed" to a particular part of the combustion chamber. A "select-fit" process at best. For that last bit of power when it's needed in racing situations.

CBODY67

 

[tbm3fan]

Got it. Unfortunately the job will have to wait another day or two. While outside I noticed it had gotten dark in under 10 minutes. Then there was a flash of lighting which is not common around here. Then there was a long, loud rolling thunder clap overhead after which it got cold real fast. Temp dropped 8 degrees on my outdoor thermometer and then it started to hail. Closed up the hood. After the hail stopped the rain started.