Spark Plug Air Leak

I recently purchased a 1977 Mini (998cc) and I'm starting to go through all the issues. Tonight I uncovered an interesting one - air coming from all four spark plugs when the car is running.

When I got the car home, I noticed the plugs were a little loose. There are two different types of plugs currently installed. I snugged all of them down. I live overseas and my torque wrench is in the mail. Tonight I was cleaning the grease off the block and wanted to let it warm up to take a drive. Then I noticed the water left over from cleaning was starting to bubble.

I didn't want to tighten the plugs too much until I get my torque wrench. I pulled all the plugs out. No signs of gas or oil but the crush washer looked worn out. I ordered a new set of plugs and wires but I won't see them for a few weeks because of shipping delays.

Should this be a cause for concern? The engine runs great and doesn't seem underpowered compared to other classic Minis I have driven. I wasn't going to be too concerned until I get the new plugs in properly torqued down but I figured I would ask the brain trust.

Those engines have cast iron heads so you're not going to strip the threads out as long as you don't go ape on the wrench to tighten the plugs.

Pull them all and carefully examine the threads in the holes. I would think that with good threads a beat sealing washer would still do a respectable job, with damaged threads leaks are very possible.

Edit: this doesn't sound like what you are describing, but I've seen several plugs that had leaks between the porcelain and metal.

Plugs (especially the plain old copper ones you need) are too cheap to think hard about this if a fresh set fixes it. While gasket seat plugs in iron heads have a spec, "snug" has never failed me. EDIT: In an iron head you'd probably snap the plug off before you hurt the threads.

Put a little anti-seize on the thread of the plugs?

I have done this and it should help seal the threads.