Spark Plug Adapters
 

I have an IO-540, and most of the 18mm to 14mm adapters are made of bronze. Is there a problem with using steel adapters?

I have also wonder this. Anyone?

Just a guess . . . .
 

I don't know from experience, but heat transfer from the plug to the head is important to keep the temperature of the plug in balance. Steel does not have the thermal conductivity nor the expansion coefficient to keep it more balanced with the aluminum head. My guess is that helped make the selection of bronze.

More accurately they are made of aluminum bronze. I suspect its due to its corrosion resistance.

Years ago I ran Autolite 386 plugs and switched over to NGK's/adaptors because those plugs seemed to be on the hot side. I have recently started running Denso L-14U plugs, which are 18mm plugs. So far so good but too early to tell.

Who sells the best adapters?

Adapters
 

Speaking from experience......don't torque an adapter into the cylinder without the sparkplug installed!:eek:

Torque the plug inside the adapter into the cylinder. I now have three adapters laying around somewhere as I could only buy them in sets of four.:(

Based on this (copied from their manual) I would say Klaus (Lightspeed Engineering), this is the way I've installed mine and have never had any trouble.

? Install adaptors in cylinder head using the supplied copper washer.
Torque to 35 - 45 ft-lbs using anti-seize compound.

? Install automotive style spark plugs with their washer. Torque to 20 ft-lbs using
anti-seize compound.

plug adapters
 

I used some from two vendors. I found the ones from Lightspeed to be superior. The other ones seemed to be bronze, one failed. The ones from Lightspeed are better may be a bronze mixed alloy. They seem harder.