Oil and spark

[KW]

This my sound a bit odd, but how conductive is motor oil? Is it less conductive than water?

My brother has been tasked with adding an extra spark plug to each cylinder on a Ford 460. The machine work on the head is no big deal for him, but customizing the valve covers for plug access is a bit of a pain in the butt.

His plan is to possibly run the wires inside the valve covers. It would make for a nice and clean setr up as long and it don't arc everywhere.

Any input is welcome,
KW

 

[Maximumcanon]

oil doesn't conduct electricity.

 

[Oil Changer]

I really don't know about the conductivity. I suppose a bottle of oil, a battery, and an Ohm meter are in order to test and see. My concern would be the oil's constant exposure to the outer jacket on the wires. A tight fitting boot on the plug should keep oil sealed out of that area. How about a splash shield between the wires and cover? Just throwin' ideas out there as requested.

 

[pajim17057]

How about some pictures of this setup when its done?

 

[Quest]

While I cannot tell you exactly how "conductive" oil is (water, being ionic bond, with a bit of "impurities", works out to be a better conductor than, say, oil, which is dielectric in nature), I can tell you that running wiring through valve covers and thus exposing your ignition related wirings to motor oil and PVC-related fumes and such, your PVC based wiring wouldn't last more than 1 year (guaranteed). Silicone may fair a bit better but that's not the point. The point is, why go through all that fuzz of running wires through valve cover and exposing your wiring to foreign elements like oil?

 

[CBDFrontier06]

He really should consider welding in some tubes to the head or valve covers to isolate the plugs and wires from hot oil. Use most any 4-valve per cylinder design as a guide. My Eclipse had tubes attached to the head that sealed against the bottom side of the valve cover, keeping the ignition system from getting oil soaked.

 

[Pablo]

Wow - not what I expected when I started to read this thread. The others have sage advice. Contaminated oil still won't conduct electricity as well as contaminated water - but that really isn't the crux of the problem.

The plugs will be sitting in oil.....interesting to say the least, probably not wise and certainly death to the wires/plug boot. I think it's worth not rednecking it - and make some tube affair as CBD suggests.

Has someone done a study and found adding another plug will add power? How will you do the electrics?

 

[CBDFrontier06]

I can't really see the advantages to this....all extra plugs added to my Ranger was spark knock when I used regular unleaded in 100+ degree temps.

Is there really enough room amonst the rocker arms for an added plug on each cylinder? If so, he better find room for tubes.

 

[forcedtalon]

Have also have to throw out there fuel/vapors in the oil itself. Sounds like a motor that will be using alot of fuel and am sure its set up loose as well for race trim.
I dont like the idea. Dont know never tryed it but just sounds more a PITA than its worth.

 

[KW]

Thanks for all the reply's, I'll forward them over to him.

I'm not sure what the dual plug 460 is going to be used for or why it needs two plugs, I'll have to ask him. He runs a one-off custom built engine shop and gets odd jobs like this one sometimes. Most of his work is stroker motors, my 555 cubic inch Cadillac would be a pretty good example.

 

[Kestas]

As I see it, the only reason for a second plug is to allow the engine to run at higher rpm. The 460 engine has a big bore (4.36"). Once you get over approximately 4" in bore, you start running into problems where flame propagation isn't fast enough with gasoline. I'm not exactly sure what these problems are, but I imagine it can result in incomplete combustion (and loss of high end power), especially at higher rpms.

 

[mpersell]

Having run a few multi plug racing engines I'll throw a little bit if experience in here. Second plugs are used to burn extra fuel or very slow burning fuel like methanol or nitro methane. The timing of the second plug is critical as it has to follow the spark of the first plug by only a slight amount. Typically you'll have a single distributor shaft turning a set of two magnetos on a gear drive with the second mag slightly behind the first in rotation. You also need a head or combustion chamber big enough to progressively burn the fuel. On most wedge head engines like the 460 its a waist of energy because it doesn't produce enough energy to overcome the added load of the second distributor.

Quote:

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As I see it, the only reason for a second plug is to allow the engine to run at higher rpm. The 460 engine has a big bore (4.36"). Once you get over approximately 4" in bore, you start running into problems where flame propagation isn't fast enough with gasoline. I'm not exactly sure what these problems are, but I imagine it can result in incomplete combustion (and loss of high end power), especially at higher rpms.

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[bruce381]

""This my sound a bit odd, but how conductive is motor oil? Is it less conductive than water?"""

Basicly when dry is NON conductive, moly additives or graphite and normal acid formation will allow slighly more conductance than new and dry but not much.
bruce