Hi DeeVeeEight,
thanks

It's a good new that the power loss between flyweel and rear wheels is notas high as i expected

carbs: I will try a 750cfm carb and see what happens

Unfortunately the Vette is quite an heavy car and probably not exhactly a "light burner"...( unless an extremely powerful engine is under the hood)So I will try the 750cfm carb and see if I have enough power for my requirements. But I have to say that I like very much also a more relaxed driving : the Vette's comfort is higher than I expected ( italian 30 years old cars are not so smooth)

have a look at this youtube video clip : Corvette vs Mini.... ( yes , my mini is a light burner...)
http://www.youtube.com/watch?v=9k2dLL50HSQ

have a nice day

Aldo

 

The way it was explained to me, was that a corner or sharp edge can cause a single point of arching, where as the rounded end allows for more surfaces for arching. Elec doesn't arch in a strip, so to speak it archs from a single point. But with the end rounded, it's not necessarily the same point, thus keeping the entire surface free of any build up. The plug stays cleaner longer, so is more reliable.

 

Especially if you're running alittle rich, you can see plainly where the strip of fire crosses the positive electrode, the entire diameter of the surface. I suppose the point you make is true, however I've never had any problems concerning that, although I do take any burr off of the square cut ends of the negative electrode. Evenin a couple of oil-burning engines I've had, (my '62 223ci prior to rebuilding it in summer '91) I never saw evidence of any extra build-up or deposits on the corners of the negative electrode. I will though, next time I change any set of plugs out, will do alittle extra close cleaning of the burr on the corners. When I read what you said about rounding the corners, I wondered if you could get even a greater length of fire where the strip of fire would not just consist of the straight line from one side of the positive electrode to the other (the diameter of the circle)but also on the rounded corners (the diameter plus). This is something I'm going to try out. When the split fire plugs came out, the filed back cheapies out-performedthem by a mile. We went through this at the track(drag) for several weekends in a row on a small block Chevy (350), Ford (351)and Chrysler product-Plymouth (340). 2/10ths of a second with the Duster right off the bat. We switched the plugs back and forth in the 340 several times that first weekend as we questioned that much amount of time difference, it just didn't seem believable.
Thanks for the input. I'm glad that someone else knows about this method.

 

Hi Texas Jim,

having some electrical-electronics knowledge , i have possibly the sparks' solution.

the arcing between 2 electrodes is EASIER if they have sharp edges , better if pointed .

In spark plugs is not possible to use pointed electrodes due to metal loss for high temp , gas corrosion ..., but where long lasting spark plugs are not an issue , is surely possible to reduce the neg electrode surface.
So both your method and the corner rounding one are effective.
I would suggest to use them together and try. in this way the neg electrode would be similar to a point

Aldo

 

Aldo,
Really glad to get your input. I knew that you had more automotive (and other)knowledge than you were letting on.
My impression of what C3 was suggesting was to round the corners, where I'd still have the straight line (of the edge of the negative electrode) but to round only the corners. It sounds like you're saying the negative electrode should idealy be pointed, if long term use was not an issue. Would this limit the spark to "one strand" rather than "the strip" the entire diameter of the positive electrode? Or would the fire actually be from the point back along the filed edges on both sides of the negative electrode? (actually aboutone and two thirds of the positive ekectrode's diameter) The whole purpose ofmy filing back the negative electrode is to getthat wider strip of fire.
In the next two days or so, I'll ask my wife if I can "draw" what I'm trying to explain in words and post the pic here on the topic.
Thanks again for brainstorming (in a sense) this theory with me.

 

Texas:
Based upon what I've seen, read, and heard, the spark is just going to occur at the shortest distance between the two electrodes whether they are sharp, pointed, or rounded. A sharp edge* does make it easier for the voltage to ionize the mixture and thus makes it easier for the spark to occur. Probably explains why cutting back the ground electrode, which better exposes the spark to the mixture, works better on an oil burner like you said previously. Also makes one skeptical of the claims of Splitfires and the infamous Fireinjectors (had a semiconductor for the spark to jump across which promptly blew/burned out). I have also used your idea about cutting back the ground electrode and "seat of the pants" feeling always seemed to be that the engine ran better.

* This is why lightening rods have a sharp point.

 

Hi Texas Jim,

I think it's not possible to have a strip of fire unless the voltage and current of the distributor are highly increased. so with the usual distributors it's just possible to have a line of fire , regardless of the shape of electrodes. But pointing the electrodes and having them to spark more easily , will surely give a more "powerful-fast" spark.

Just an idea : why don't you run a spark plug outside the engine ?. You will see if the spark it's a line or a strip ( after the mod)

73shark is correct in my opinion

Anyway : I have to replace soon my spark plugs . I think I will both round and reduce the neg contact

Aldo

 

Aldo,
If youfile the negative electrode back like I was saying, and install the plug and run it, with an engine that runs just alittle rich, you can plainly see where the fire jumps. and it isthe entire diameter of the positive electrode. (one side to the other)

73shark,
With a points (breaker) ignition, you can physically tell a difference in the running of the engine. Seems that it's not AS noticeable with the electronic.

 

Another dynamic that enters into the equation is that the breakdown voltage increases with pressure. A plug that seems to fire normally out in the open may not fire at all under compression pressures.

 

Very True, 73shark. The test, like I posted, is to run the plug for a day or so and then check and see that line across the diameter of the positive electrode that the spark leaves.
Where I posted the comment to you about you saying that you felt (seat of the pants)the difference when the plug is filed was my agreement with what you stated. From my experience, I can feel it more when I've used those filed plugs in a vehicle (my '62 p/u) with a points ignition. Why, I have no idea.