plug reading

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BigRichieO

BigRichieO

Colorado Mopar
Joined
Jul 16, 2006
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Location
Arvada, Colorado
I am having a fuel problem that I have posted about but I didn't just want to add to that post for fear that someone would by pass it since they might have already looked at the thread.

I pulled one of my spark plugs to see if I was running too rich?? From the looks of this plug I was thinking it looked pretty good or maybe even a little lean. What do you guys think from the picture of the plug. Is this going to be an air/fuel setting that I need to change or is it maybe a timming issue? Let me know what you think. Thanks.

DSC00546.jpg


mopar_logo_ (VS).jpg
 
Dear God, lean that poor thing out!

Reference this for some help.

plugs.jpg
 
way too rich /what kind of carb are you running? also when you think you might be close the correct way to read is to run the car at wot and shut the engine off in this condition /then coast to a stop pull the plug /white = lean/black=rich and tan is on the money
 
They look like my plugs. When you say lean it out, what exactly do you mean? I have a Holley 3310 on 360.
Thanks
 
step the jets down(lean out fuel feed thru metering plate)
see how the plug is black(like a carbon build up)
and you can actually see what looks like moisture on it
unless you're burning oil a little :(
 
bbeep71 said:
They look like my plugs. When you say lean it out, what exactly do you mean? I have a Holley 3310 on 360.
Thanks
Click to expand...

If your plugs look like this the air bleeds are too small on the idle circuit. Mid 70's jets are small enough for a 750 cfm carb. Looking at this from a tuning stand point, a good high output ign. system won't allow the plugs to show any color, in other words the plugs will stay clean all the time. So from tuning fuel cars we have to look at the color change at the ground strap and the spark plug threads. First the ground strap shows the timing, and correct timing of the engine will have the burn mark or pattern on the ground strap in the middle of the bend. Then the correct amount of heat or air/fuel efficentcy will be shown in the amount of heat transferred to the plug threads, the correct air/fuel mixture will have the top 2 threads dry or black or grey depending on what color the plug threads are to start with. You may see a few threads that look wet but don't worry as this just helps to show better how far the heat is traveling. When you achieve this then the engine will be at it's peak tune.
 
BJR Racing said:
If your plugs look like this the air bleeds are too small on the idle circuit. Mid 70's jets are small enough for a 750 cfm carb. Looking at this from a tuning stand point, a good high output ign. system won't allow the plugs to show any color, in other words the plugs will stay clean all the time. So from tuning fuel cars we have to look at the color change at the ground strap and the spark plug threads. First the ground strap shows the timing, and correct timing of the engine will have the burn mark or pattern on the ground strap in the middle of the bend. Then the correct amount of heat or air/fuel efficentcy will be shown in the amount of heat transferred to the plug threads, the correct air/fuel mixture will have the top 2 threads dry or black or grey depending on what color the plug threads are to start with. You may see a few threads that look wet but don't worry as this just helps to show better how far the heat is traveling. When you achieve this then the engine will be at it's peak tune.
Click to expand...
And yourd to BJR I copied and saved it too :-D
 
how do you mess with the air bleeds. My plugs look similar
 
Do you have a pin drill? If so then enlarge the outer most air bleeds .005. The outer most air bleeds are the 4 outer most holes in the top of the carb. If you look down the top of the carb and you can see these in the rear. You will have 2 holes located next to the discharge nozzle and 2 holes farther out, The 2 that are next to the diacharge nozzle are the high speed bleeds, leave them alone and you'll have 2 more that are further out, these are you Idle bleeds. These are the 2 that I'm takling about, if you enlarge these 2 .005 it will make a major difference. But be careful are the drills are tiny and will break easly. You can get one of these drill at a local welding shop, they call them tip cleaners for cutting torches. They have drills from .012 to .060, you will need a good dial caliper to measure them, something like a NSK.
 
so drill the outside air bleeds to .005? my 2 air bleeds that are on the outside inside of the air horn are bigger than all the other 6
 
I can put a 1.5mm alen wrench in the 2 big ones. It doesnt go all the way down but it goes in
 
The outside air bleeds should be about .063 or so and I want you to find out what drill that they are and drill them .005 larger. .068-.070 will do the trick, but if you woble and drill them larger then you'll have to jet the primary side up about 3-4 sizes.

You need to have the front fuel bowl off and have a air chuck handy to blow out the chips that the drill will create. When you look at the carb when the fuel bowl is off you'll see 4 holes near the top ring of the carb just under the airhorn that coinside with the air bleed holes in the airhorn. These are the ones that you need to make sure that they aren't restricted in any way. When you get this done you should be fine.
 
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