The Dodge Challenger Message Board

What would you guys suggest for my stock 383, stock exhaust/manifold, Holley Street avenger 670, cam Mopar purple shaft 280/474, orange box EI? Its seems like time to change them after 5 years and a few thousand miles. I hear all kinds of ads about hot plugs. Does the local auto parts guy stock them?

The only improvements to what you have already would be more torque and better mileage.

Plugs in general do not make much more power no matter what ads or people may tell you. But there are quality isues which I will talk about in a moment and some plugs do indeed burn the mixture better and so give slightly better results.

But first what makes better torque and MPG?

The answer is a GOOD spark and complete ignition of the air fuel mixture.

It is the spark from your coil and orange box that depends on complete ignition. So that is the area you would have to improve if you want better results.
A stock ignition does not ignite the mixture 100% of the time. In fact you will be lucky if it is 85% of the time if you had a points distributor.

As rpm increases the problem is worse. This kills torque and fuel economy.

Don at FBO comissioned an "independant" company to do these tests.

http://www.4secondsflat.com/a688dropcyltest.html

Now I don't like Don. He is an arse. But these results do not supprise me.

As you can see the main factor is a good coil. Which is why I have a good coil. But i also use a capacitive discharge ignition system. Whic kind of makes certain that every cylinder fires as it should.

The orange box does not work very well. It is better than points but even MoPar always put the chrome box on their race cars because of the cylinders dropping out at high rpm.

So if you want to improve things look in this area.

Now to spark plugs.

I don't know what you mean by "hot" plugs but plugs do come in a range from Hot to cold in order to warm to the correct temperature for the engine.
If the plug runs too hot (plug tip looks white) then you need a plug that takes the heat. If it runs too cold (dark plug tip) the plug needs to be heated up more.

This is what the plug range is for. If your plugs are a nice tan colour the heat range is correct.

Now. Asking people what make of plug is best is like asking what is there favorite colour.

Some will say "Champions made more power on the dyno". Some will say "I will NEVER use Champions again!"

But the truth is out there...

Avoid multiple or split electrode plugs. Waste of money and time.

Sparks jump from sharp edges more easily then from a flat surface. This is an established fact discovered 150 years ago. However sharp points wear away faster unless made from exotic metals or alloys.

So plugs with a sharp point or a U-grove will work better. ONE sharp point is best of all.
The spark will jump sooner and burn longer. Just what you want.

The next thing to consider is build quality. I have broken so many Champion plugs I have long lost count. I don't use them any more.

The only plugs I would use are the DENSO (also sold as Accel in the US so the rednecks don't realise they are Japanise) or NGK plugs.

I have just fitted the new sharp Iridium point NGK plugs to my 440. I have not tried them yet but along with the MSD ignition am expecting good results from them.

www.ngk.com

NGK-5's here. I too used to use Champions and Autolite both were "acceptable" but the NGK's seem to last longer and the engine stays in tune with it longer. Standard Orange box plus electronic distributor and electronic coil. I am going to the MSD coil next, then would eventually want to use either a Crane or MSD6 box and mount that box behind the glove box were the orange box is presently located. I have a complete MSD6,(MSD6 box, blaster 2 coil, billet dizzy, 8.5mm SC wires, NGK plugs,)on my Power Ram and it stays in tune for years!

Good article Thanks Dave!

airfuelEddie wrote:I am going to the MSD coil next,

The FBO coil looks a better bet according to that test list I linked to.

Damn that Don.

I think I'll use the FBO coil Dave. Is it the same size as the regular moPar Black electronic coil. I could just paint it black, or leave it alone. The Shaker covers darn near everything anyways.

It looks pretty normal to me.

Cool, thanks for the pics Dave, yes it should fit fine. I really need to get one. It's that much better than the "standard" electronic huh.

I installed the FBO kit about a year ago along with a dizzy recurve. Man it made a big difference in power.(Sorry Dave ) Still using manifold vacuum for the advance diaphram as FBO recommended. I remember Dave telling me that was wrong but what to do it is in the instructions?

I did aquire a slight bit of detonation with Don's modification at 12 degrees initial timing. Not sure if larger secondary jets would cure this but I plan to give it a try. It seems with this setup I'm right on the edge of needing a fuel additive. I filled up at a brand new Chevron station recently and no pinking that day. Must had been the fresh fuel. Can anyone recommend a good octane booster.

Jon wrote:I installed the FBO kit about a year ago along with a dizzy recurve. Man it made a big difference in power.(Sorry Dave ) Still using manifold vacuum for the advance diaphram as FBO recommended. I remember Dave telling me that was wrong but what to do it is in the instructions?

I did aquire a slight bit of detonation with Don's modification at 12 degrees initial timing. Not sure if larger secondary jets would cure this but I plan to give it a try. It seems with this setup I'm right on the edge of needing a fuel additive. I filled up at a brand new Chevron station recently and no pinking that day. Must had been the fresh fuel. Can anyone recommend a good octane booster.

Thanks Dave and Jon, I think I will use the coil and module. I already have fast curve set in the dizzy,(12 Initial 24 centrifugal but can't use any vac. adv. due to the Pro-max billet metering plates). As far as octane boosters Jon, I have "heard" that V.P. fuel booster is good but all the "boosters" ever did for me was turn the plugs orange. Is there anywhere you can get Race Fuel and use that as the booster? I think it would work better.

Thanks for the advice Eddie. I can get race fuel or AVGas. How much do you think would be needed for a tankful?

The FBO kit comes with a new ballest resistor. I put an Ohm meter on the FBO, an Accel, and a Stocker. FBO lets alot more current thru. Maybe that helps obtain such a hot spark.

Also Don's module caused my stock/rebuilt using R/T Engineering tach to read double at idle to about 1500 RPM. They call it double fire at idle syndrome I think.

Also you will need a high temp rotor and cap as the additional spark supposidly(?) melts the contact points. (they come in the kit)

Other then that it's a tire smoken deal.

Jon,I really dont know what the ratio would be. I would think that each engine would be a little different anyway. I would start with a gallon of av gas or race fuel and fill up as normal. Then road test and write down when the pinging or detonation is present. What the temp was and "load" conditions, ie cruising, really getting on it or racing,(not that we would do that thing on the street) was the engine fully warmed up ect..Then if the detonation continues keep adding another gallon until it stops