Plug extender question ???

They keep the dirt out of the plug hole. They also hold the wire in the center of the plug hole so that the wire doesn't short out against the side of the valve cover. I think there could be a better way of connecting the wire to the plug though. Ferrari seems to like these little points of connection. Electrically, they are inefficient. So a better connection would be in order for me anyway.

Bob Wassam

 

I'd like to hear the physics behind this -- seems unlike IMO (but good techno-babble justification ).

Bob gave the first one -- that it allows the use of a more heat resistant material where you need it (even the later cars, where the extender is just a 0 ohm connector, use them). The second reason is that if the impedance of the secondary discharge path gets too low, this more highly stresses the output transistors inside the ignition ECU supplying the primary coil current (and can blow them up).

Doesn't mean that you can't get an aftermarket wire + plug to work replacing the stock wound wire + extender + plug (and I believe the ign ecu in all of the 308QV are "improved" versions over the very fragile ones in the 308-2Vi), but you are taking some risk if you significantly lower the secondary impedance. None of us like the prices of the stock wires or extenders, but IMO unless you have a very, very well-executed modification, I'd deduct the equivalent $ value from any 308 with non-stock ignition components (so you just delay the expense until the sale).

What is your specific "problem" -- price too high?

 

The spark plug extender is "old technology" IMHO. Modern wires are well insulated, well shielded, and made from heat resistant materials that can stand up to the heat on top of our engines and in those holes. A friend of mine has Taylor wires on his car and runs them without extensions, with the straight plug boot inserted into the hole through a regular cap for the hole. You really do need the cap over the plug hole to keep water and dirt out of there. The cap itself keeps the wire centered. I'm seriously thinking of doing the same thing on my '78 308 as I'm putting the wires together for the XDI, and just eliminate the extender, which is a weak link in the system, AFAIAC.

Steve

 

When it came time to replace the plugs on my '84 Boxer, I wanted to run more modern, Platinum plugs, but could not do so because the ferruls on top of the plugs were not removable nor compaitble with the plug extenders. I removed all the plug extenders and fixed the plug caps directly to the plugs. I left the rubber covers in place to keep the dirt out of the plug holes.

Having designed ignition systems, my conclusion was the extenders are an RFI device, which is unnecesary with modern plug / wire systems.

My system works perfectly, there is no intefernce on the radio, and I've had no problems at all.....and loosing that extender must improove HT voltage and efficiency.

Anyone want to buy 12 extenders?

Robert