[Brian Morency]

So I just remembered hearing something about a different spark plug wire routing on some Chevy heads that increased HP. I believe it had something to do with adjusting the timing or dropping the dizzy in different so that some how an increase in horsepower was obtained. Can some one help me out here? Trying to figure out what this was all about or was this just some dream I had?

[timothale]

There can be a problem when wires are routed close together and current passing thru a wire can create a magnetic field that induces a voltage in another wire close to it. That's the way transformers and coils work. This also can cause radio interference. Detroit used to have specific wire routing diagrams, specifications on type of wires to use, or shielded wires, etc. .

[DoubleVision]

I`ll explain a few things, for some it`s kind of hard to take in but it`s really simple. Lets start with the basics, electricity is like water, it`s smart, but lazy. It will always take the path of least resistance. Now, with that out of the way, lets get into plug wires. Cheapy parts store wires have solid cores, these work fine for daily drivers, but even for that role I don`t use them.
Solid core wires have high resistance, now think back on smart and lazy, path of least resistance. if There`s a high amount of resistance in the plug wire and the spark can find a easier path it`s sure going to take it and this can cause many problems in a high performance engine such as cross fire detonation which is the worst kind. Now we look at spiral core spark plug wires, these have considerably less resistance, some get down to some pretty low levels, I mostly use Moroso blue max 875 ohm spiral core wires. You pay more for them, but they last far longer than solid core wires plus do a much better job. Now, on to looming the wires. If the wires are crossed up, and it doesn`t matter which type of wires you use this can cause cross firing and we already know what damage that can do. Back in the early days Smokey Yunick didn`t pay any attention to the routing of plug wires, then he decided to do a experiment. He connected up 8 plug wires to a machine, and laid them over a metal work bench, then shut the lights off so it was completely dark. What he saw he said he`d never forget, the wires were lighting up from the electrical energy leaking around them and they were arcing fire everywhere creating all kinds of cross fires. Afterwards it taught him to pay very close attention to the routing of the spark plug wires. However, I think that was in the days before they had spiral core wires avalible and with there lower resistance aren`t as prone to doing so, but I still recommend to others take your time and route them correctly and away from each other. No, it won`t give you anymore horsepower, but it could save your engine especially when you consider the problem on the small block chevrolet, 1 8 4 3 6 5 7 2 As you see, 5 and 7 fire one behind the other plus they are side by side, if 5 arcs 7, and 7 has just filled the cylinder with air fuel mixture and the piston is at bottom dead center about to start it`s way up and a cross fire arc sets the charge off in 7 bad things happen as the combustion hits it with the piston half way up the cylinder which combustion makes it want to go back down but it can`t. Now you know more useless information.

[retromotors]

Brian,
Are you by any chance referring to changing the firing order rather than the wire routing? I understand that is seen by some to be more power, smoother engine, etc.
If so, a search should bring up some threads. I think #4 and #7 were the swapped plugs. Calls for a special cam.

[lmsport]

Why would a solid copper core wire have higher resistance than a carbon core wire?

There are a number of reasons to use a spiral core wire in most applications, but horsepower is not one of them.

[oldbogie]

Originally Posted by Brian Morency

So I just remembered hearing something about a different spark plug wire routing on some Chevy heads that increased HP. I believe it had something to do with adjusting the timing or dropping the dizzy in different so that some how an increase in horsepower was obtained. Can some one help me out here? Trying to figure out what this was all about or was this just some dream I had?

I suspect you're thinking of the cylinder 7 to 4 firing order switch. This takes more than messing with the distributor and plug wiring, it takes a special ground cam that re-times the intake and exhaust sequence for these two cylinders. The power gain is minor, it is more done to better balance the power strokes on the crank to improve structural reliability of the block and crank at high RPM, high power settings. Some magazine articles and web blogs claim upwards of 20 hp can be gained, my experience is more in the range of 3 to 5 for the same peak RPM. But this greatly reduces number 7's rather ugly tendency to detonate long before any-other cylinder, this lets you push the engine to a higher RPM before hitting the ping limit which is where the magic 20 horses is coming from, but you've got to have it spinning between 7 and 9 grand to see this. It's not a very beneficial exercise for a street engine although the newer LS engines incorporated this as a production change compared to the GEN I and II small block. Ford also made a running production change in their engines as well.

Bogie

[Brian Morency]

Thanks Bogie, You hit the nail on the head.