Spark Plugs
- Thread starter Rick
- Start date
Autolite ...
"The Bat" out of hell
Member
For a big cam or tall highrizer manafold,sometimes a one or two step hotter plug then stock,as poor idel can load stock plug up. Still coldist plug ya can run and stay clear is best. That aircleaner is small for 351/600,be sure to keep it very very clean
Mike
Well-Known Member
Rick, with a couple of exceptions, any plug testing I have done shows a spark plug is a spark plug is a spark plug. I recommend avoiding any of the plugs that talk about having small, pointed electrodes. The small electrode produces a small flame kernel. Likewise, I avoid plugs with multiple side electrodes, as the additional electrodes will shield the flame kernel more than a single electrode plug.
Anyone who says Brand A spark plugs make more power than Brand B spark plugs is either comparing apples to oranges or has never seen the inside of a dyno room. If you match up plug designs from different manufacturers, you will not see a lick of power, changing from one brand to another. It just isn't there to be found.
Other than that, I do prefer to use a plug with a cadmium-plated shell, as opposed to a black-oxide shell. The cad shell makes it a lot easier to read the heat in the plug, because the threads will discolor a bit. If you're using a plug with a black shell, you cannot see the discoloration.
If you're satisfied with the tune-up you have in the car, reading plugs is really not something you will be dwelling on, other than looking for obvious problems when you're changing plugs.
If you're trying to sort out a tune-up, plug reading is invaluable. But remember, idle time will kill any chance you have to read the plug. Get the car on a flat stretch of pavement and install fresh plugs. Get in the car, buckle up, start the car (don't be revving the motor, that won't help) and run it, remembering to cut the ignition as you are stepping off the throttle. The pull the plugs out and see what you have. Here's what you're looking at and what you're looking for -
Look at the area shown on the far left plug. The face of the shell is going to tell you how close you are in jetting. For a street-driver, you'll want to see a taste more color than on this plug.
Now look at the plug second from left. Look at the insulator, which should still be bone-white. It won't take on color that quickly, so it should still be white. If you see any signs of "pepper", i.e. black spots, then you know the engine is detonating. Carbon is getting rattled off the piston dome and chamber and is being deposited on the insulator. If you're seeing pepper, you also want to look for any signs of metal-flakes on the insulator. If you see them, knock some timing out of the motor and add some jet, before you try to drive it home. That metal is piston dome. Don't be afraid to get in there with a strong magnifying light, so you can get a real close look. Pepper is usually easy to see, but a magnifier light can help.
Looking at the two plugs at the right, notice how the side electrode has a color line, right at the bend of the electrode? For a street motor, that is just about as close to perfect as you will ever get. A race motor might want another 1/2° of timing, or so, just enough to move that line a little deeper into the bend. That line is telling you where your timing is. if you look at the plug second from left, it doesn't seem that particular hole is the same as the two plugs on the right. The hole that second from left plug came out of is wanting a little more timing. Which is why you rarely ever get a close look at Pro Stock or Pro Mod motors, because, among other things, they don't want you to see how they are adding or taking away timing in individual cylinders. As for myself, I know n-o-t-h-i-n-g. :angel:
Additionally, look at the threads on the plug. A street driver with a 3/4" reach plug like these is going to have a color line on the threads and you will want it about 3 threads up from the face of the shell. A race motor would want to see maybe one more thread turning color.
Another myth to be banished, because it is so often misunderstood.
A "hot" spark plug does not provide any more spark energy than a "cold" spark plug. A plug's heat range is an indication of the range of temperatures the plug will be most comfortable operating within.
One of the most typical differences between hot and cold plugs is the length of the insulator shell. A cold plug will generally have a shorter insulator, which will allow the heat from the tip of the plug to be dissipated through the threads into the cylinder head more rapidly. A hot plug will generally have a longer insulator, providing a longer heat dissipation path, leaving more of the insulator at a higher temperature than the cold plug.
Typically, a colder plug will be used in a high compression engine, as the engine takes advantage of the higher compression to develop more chamber heat. A hotter plug will have a higher insulator temperature and can lead to detonation. On the other hand, a colder plug being used in a lower compression engine can actually be too effective at cooling the insulator, which can create poor burn in the chamber.
If you're looking to find more power in your spark plugs, be sure you have the correct heat range plug for your application, run as wide a gap as your ignition system will allow and index your plugs into each chamber, so the side electrode ends up being near the top of the chamber, allowing for better flame kernel exposure to the cylinder's fuel charge. Beyond that, it's all smoke and mirrors.
Anyone who says Brand A spark plugs make more power than Brand B spark plugs is either comparing apples to oranges or has never seen the inside of a dyno room. If you match up plug designs from different manufacturers, you will not see a lick of power, changing from one brand to another. It just isn't there to be found.
Other than that, I do prefer to use a plug with a cadmium-plated shell, as opposed to a black-oxide shell. The cad shell makes it a lot easier to read the heat in the plug, because the threads will discolor a bit. If you're using a plug with a black shell, you cannot see the discoloration.
If you're satisfied with the tune-up you have in the car, reading plugs is really not something you will be dwelling on, other than looking for obvious problems when you're changing plugs.
If you're trying to sort out a tune-up, plug reading is invaluable. But remember, idle time will kill any chance you have to read the plug. Get the car on a flat stretch of pavement and install fresh plugs. Get in the car, buckle up, start the car (don't be revving the motor, that won't help) and run it, remembering to cut the ignition as you are stepping off the throttle. The pull the plugs out and see what you have. Here's what you're looking at and what you're looking for -
Look at the area shown on the far left plug. The face of the shell is going to tell you how close you are in jetting. For a street-driver, you'll want to see a taste more color than on this plug.
Now look at the plug second from left. Look at the insulator, which should still be bone-white. It won't take on color that quickly, so it should still be white. If you see any signs of "pepper", i.e. black spots, then you know the engine is detonating. Carbon is getting rattled off the piston dome and chamber and is being deposited on the insulator. If you're seeing pepper, you also want to look for any signs of metal-flakes on the insulator. If you see them, knock some timing out of the motor and add some jet, before you try to drive it home. That metal is piston dome. Don't be afraid to get in there with a strong magnifying light, so you can get a real close look. Pepper is usually easy to see, but a magnifier light can help.
Looking at the two plugs at the right, notice how the side electrode has a color line, right at the bend of the electrode? For a street motor, that is just about as close to perfect as you will ever get. A race motor might want another 1/2° of timing, or so, just enough to move that line a little deeper into the bend. That line is telling you where your timing is. if you look at the plug second from left, it doesn't seem that particular hole is the same as the two plugs on the right. The hole that second from left plug came out of is wanting a little more timing. Which is why you rarely ever get a close look at Pro Stock or Pro Mod motors, because, among other things, they don't want you to see how they are adding or taking away timing in individual cylinders. As for myself, I know n-o-t-h-i-n-g. :angel:
Additionally, look at the threads on the plug. A street driver with a 3/4" reach plug like these is going to have a color line on the threads and you will want it about 3 threads up from the face of the shell. A race motor would want to see maybe one more thread turning color.
Another myth to be banished, because it is so often misunderstood.
A "hot" spark plug does not provide any more spark energy than a "cold" spark plug. A plug's heat range is an indication of the range of temperatures the plug will be most comfortable operating within.
One of the most typical differences between hot and cold plugs is the length of the insulator shell. A cold plug will generally have a shorter insulator, which will allow the heat from the tip of the plug to be dissipated through the threads into the cylinder head more rapidly. A hot plug will generally have a longer insulator, providing a longer heat dissipation path, leaving more of the insulator at a higher temperature than the cold plug.
Typically, a colder plug will be used in a high compression engine, as the engine takes advantage of the higher compression to develop more chamber heat. A hotter plug will have a higher insulator temperature and can lead to detonation. On the other hand, a colder plug being used in a lower compression engine can actually be too effective at cooling the insulator, which can create poor burn in the chamber.
If you're looking to find more power in your spark plugs, be sure you have the correct heat range plug for your application, run as wide a gap as your ignition system will allow and index your plugs into each chamber, so the side electrode ends up being near the top of the chamber, allowing for better flame kernel exposure to the cylinder's fuel charge. Beyond that, it's all smoke and mirrors.
Thanks Mike now i have to digest it all.Rick, with a couple of exceptions, any plug testing I have done shows a spark plug is a spark plug is a spark plug. I recommend avoiding any of the plugs that talk about having small, pointed electrodes. The small electrode produces a small flame kernel. Likewise, I avoid plugs with multiple side electrodes, as the additional electrodes will shield the flame kernel more than a single electrode plug.
Anyone who says Brand A spark plugs make more power than Brand B spark plugs is either comparing apples to oranges or has never seen the inside of a dyno room. If you match up plug designs from different manufacturers, you will not see a lick of power, changing from one brand to another. It just isn't there to be found.
Other than that, I do prefer to use a plug with a cadmium-plated shell, as opposed to a black-oxide shell. The cad shell makes it a lot easier to read the heat in the plug, because the threads will discolor a bit. If you're using a plug with a black shell, you cannot see the discoloration.
If you're satisfied with the tune-up you have in the car, reading plugs is really not something you will be dwelling on, other than looking for obvious problems when you're changing plugs.
If you're trying to sort out a tune-up, plug reading is invaluable. But remember, idle time will kill any chance you have to read the plug. Get the car on a flat stretch of pavement and install fresh plugs. Get in the car, buckle up, start the car (don't be revving the motor, that won't help) and run it, remembering to cut the ignition as you are stepping off the throttle. The pull the plugs out and see what you have. Here's what you're looking at and what you're looking for -
Look at the area shown on the far left plug. The face of the shell is going to tell you how close you are in jetting. For a street-driver, you'll want to see a taste more color than on this plug.
Now look at the plug second from left. Look at the insulator, which should still be bone-white. It won't take on color that quickly, so it should still be white. If you see any signs of "pepper", i.e. black spots, then you know the engine is detonating. Carbon is getting rattled off the piston dome and chamber and is being deposited on the insulator. If you're seeing pepper, you also want to look for any signs of metal-flakes on the insulator. If you see them, knock some timing out of the motor and add some jet, before you try to drive it home. That metal is piston dome. Don't be afraid to get in there with a strong magnifying light, so you can get a real close look. Pepper is usually easy to see, but a magnifier light can help.
Looking at the two plugs at the right, notice how the side electrode has a color line, right at the bend of the electrode? For a street motor, that is just about as close to perfect as you will ever get. A race motor might want another 1/2° of timing, or so, just enough to move that line a little deeper into the bend. That line is telling you where your timing is. if you look at the plug second from left, it doesn't seem that particular hole is the same as the two plugs on the right. The hole that second from left plug came out of is wanting a little more timing. Which is why you rarely ever get a close look at Pro Stock or Pro Mod motors, because, among other things, they don't want you to see how they are adding or taking away timing in individual cylinders. As for myself, I know n-o-t-h-i-n-g. :angel:
Additionally, look at the threads on the plug. A street driver with a 3/4" reach plug like these is going to have a color line on the threads and you will want it about 3 threads up from the face of the shell. A race motor would want to see maybe one more thread turning color.
Another myth to be banished, because it is so often misunderstood.
A "hot" spark plug does not provide any more spark energy than a "cold" spark plug. A plug's heat range is an indication of the range of temperatures the plug will be most comfortable operating within.
One of the most typical differences between hot and cold plugs is the length of the insulator shell. A cold plug will generally have a shorter insulator, which will allow the heat from the tip of the plug to be dissipated through the threads into the cylinder head more rapidly. A hot plug will generally have a longer insulator, providing a longer heat dissipation path, leaving more of the insulator at a higher temperature than the cold plug.
Typically, a colder plug will be used in a high compression engine, as the engine takes advantage of the higher compression to develop more chamber heat. A hotter plug will have a higher insulator temperature and can lead to detonation. On the other hand, a colder plug being used in a lower compression engine can actually be too effective at cooling the insulator, which can create poor burn in the chamber.
If you're looking to find more power in your spark plugs, be sure you have the correct heat range plug for your application, run as wide a gap as your ignition system will allow and index your plugs into each chamber, so the side electrode ends up being near the top of the chamber, allowing for better flame kernel exposure to the cylinder's fuel charge. Beyond that, it's all smoke and mirrors.
I think the ones i used are the AutoLight AP45 there one notch over the OEM 45's
Ted Brown
Member
It is easy to feel which plug gave up the fight, just slap each header tube, the cool one is not firing much if any, I only change the dead players... PS, If you are having an oil fouling problem, a temp fix to keep the plug firing, is to use a jump spark, make the spark jump about a 1/4" before it gets to the plug, get there or home in fine fashion. I had a friend once that used that setup on all 8 plugs, all the time... Really looked wild at night, all them sparking wires, he had them separated using a leather washer, and the wires soldered to itself on each side. I am sure there is an easier and better way to do that... 
