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Old 12-25-2011, 08:04 PM
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Spark Plug reading?

I was wondering if you guys could take a look at these plugs and tell me what you see needs adjusting. I'm confusing myself. There are a couple that are black and the rest are brown like you see in the pic. #3 was dry at the tip, but a little wet on the threads (fuel). All other plugs were pretty much dry. Should I go a step hotter on the plugs. These are a new set of plugs That I put in after I adjusted A/F on the carb for highest vaccum. The only thing I've done different after that was change the module out in my HEI. By the way this is a brand new 496 that I'm still working the bugs out of. I started to get a slight surge when I stop at the light, which is what made me check the plugs. I checked for vac leaks also before I pulled the plugs to see if that was causing the slight surge. The carb is a Holley 4150 850cfm double pumper. Any advice is appreciated! Thanks,
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Old 12-26-2011, 06:00 AM
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Quote:
Originally Posted by 396chevelle
I was wondering if you guys could take a look at these plugs and tell me what you see needs adjusting. I'm confusing myself. There are a couple that are black and the rest are brown like you see in the pic. #3 was dry at the tip, but a little wet on the threads (fuel). All other plugs were pretty much dry. Should I go a step hotter on the plugs. These are a new set of plugs That I put in after I adjusted A/F on the carb for highest vaccum. The only thing I've done different after that was change the module out in my HEI. By the way this is a brand new 496 that I'm still working the bugs out of. I started to get a slight surge when I stop at the light, which is what made me check the plugs. I checked for vac leaks also before I pulled the plugs to see if that was causing the slight surge. The carb is a Holley 4150 850cfm double pumper. Any advice is appreciated! Thanks,
Plug on right looks to be burning about right. The one on left looks to be carboned up like from idling. Intake design/type can effect the a/f distribution enough at low speeds to cause the plugs to look quite a bit different. If the engine is allowed to idle, what you're seeing then is the idle a/f ratio more than anything else.

If you want to get a better idea of the air/fuel ratio, you have to do a "plug chop" to show you the color. This would be done at the RPM/load where you were interested in checking, i.e. if you want to know what the a/f ratio looked like at WOT, you'd run it at WOT to do the chop. Same thing for midrange cruise, etc. Idle mixture can be checked in various ways, but before doing any of that, the timing should be dialed in. Depending on the cam you might need quite a bit more initial timing than would seem 'normal'.

There are instances where the carb is jetted differently side to side, called "staggered jetting". So it will help to know what the cam and intake specs are and under what conditions were the plugs above being used.
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Old 01-04-2012, 06:00 AM
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What brand of plugs r these?
Swap the black sooty plug for the other one n see what happens
Clean them first
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Old 01-04-2012, 09:10 AM
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wet plugs ?

ill agree with the other posts - also - try looking down the carn throats when warmed up & use a flashlight. is any fuel dripping down the accl boosters? fuel level slightly high? ant fuel puddling in carb? Ive had bad plugs also -yet rare - no matter what brands.
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Old 01-04-2012, 09:37 PM
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Couple of notes for you,

Generally if the threads are wet, it is oil working its way up the threads. If the engine is new, i wouldnt be too worried its still breaking in and you will see some oil now and then till everything is seated.

You adjusted the Idle air screws, not the air fuel ratio, as soon as you pick up the throttle those adjustments are moot.

If you have a "surge" just as you come to a stop, either the idle is too low, the convertor is too high of a stall, possibly a high/low float, rear idle circuit is too high (dropping fuel with the blades closed) or even a broken advance weight spring. Hard to say.

If you want to start eliminating the carb, srcew the rear bleeds all the way in and cut the flow. If that helps somone has probably bob vila'd the carb and turned the rear blade stop in or out under the carb feeling they were doing something trick.

As far as the plugs go, the best advice was to swap the black plug to a good hole.
If it persists start looking at things that would make a cyl run rich, weak spark (bad wire, contact on cap, star wheel on the shaft damaged) exhaust gas entering the chamber on intake stroke, tight valve, oil entering into the chamber like bad valve seal, bad ring, bad guide etc.

hope you figure it out and have fun.
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Old 01-05-2012, 03:06 PM
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Quote:
Originally Posted by topwrench
What brand of plugs r these?
Swap the black sooty plug for the other one n see what happens
Clean them first
There Champions
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Old 01-05-2012, 06:54 PM
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Quote:
Originally Posted by 396chevelle
I was wondering if you guys could take a look at these plugs and tell me what you see needs adjusting. I'm confusing myself. There are a couple that are black and the rest are brown like you see in the pic. #3 was dry at the tip, but a little wet on the threads (fuel). All other plugs were pretty much dry. Should I go a step hotter on the plugs. These are a new set of plugs That I put in after I adjusted A/F on the carb for highest vaccum. The only thing I've done different after that was change the module out in my HEI. By the way this is a brand new 496 that I'm still working the bugs out of. I started to get a slight surge when I stop at the light, which is what made me check the plugs. I checked for vac leaks also before I pulled the plugs to see if that was causing the slight surge. The carb is a Holley 4150 850cfm double pumper. Any advice is appreciated! Thanks,
As Cobalt points out the right side looks OK the left is carboned up which could be manifold distribution, excess fuel on one side, engine operating temp too low, this can be a problem with the front two cylinders that see coolant right off the pump so they are cooler than everybody else. A wiped cam lobe and lifter, or simply the plugs that were all rich and dark from early tuning attempts and some just haven't cleaned up yet because they miss or late fire, or a leaking head gasket, a valve leaking oil down a guide, rings not yet sealing up enough. The fuel wet threads can be as much an indicator that the plug is miss-firing as it is seeing a rich mixture.

I'd throw them away, put in a fresh set and run it a while then take a new look and report the results back here. This time keep them in order so you can see if any are on common sides of the intake, or are next to each other, at the front or rear of the engine, etc. This is so we can consider trends if there seem to be any of related or common problems between cylinders.

On second thought I wouldn't throw these plugs out, keep them for reference but don't run 'em again. And don't get them confused with the next set you take out.

Bogie
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Old 01-05-2012, 08:06 PM
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Quote:
Originally Posted by oldbogie
As Cobalt points out the right side looks OK the left is carboned up which could be manifold distribution, excess fuel on one side, engine operating temp too low, this can be a problem with the front two cylinders that see coolant right off the pump so they are cooler than everybody else. A wiped cam lobe and lifter, or simply the plugs that were all rich and dark from early tuning attempts and some just haven't cleaned up yet because they miss or late fire, or a leaking head gasket, a valve leaking oil down a guide, rings not yet sealing up enough. The fuel wet threads can be as much an indicator that the plug is miss-firing as it is seeing a rich mixture.

I'd throw them away, put in a fresh set and run it a while then take a new look and report the results back here. This time keep them in order so you can see if any are on common sides of the intake, or are next to each other, at the front or rear of the engine, etc. This is so we can consider trends if there seem to be any of related or common problems between cylinders.

On second thought I wouldn't throw these plugs out, keep them for reference but don't run 'em again. And don't get them confused with the next set you take out.

Bogie
I'll pull the plugs this weekend and put it a new set. When I pull the new set to see how there doing I'll mark them and let you know which cylinder they were firing in! Thanks for the info. WOT or Cruising speed?
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Old 01-05-2012, 11:31 PM
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Once you put the fresh set of plugs in, take a magic marker and put a reference line at 12 0'clock on each plug. That way you will know if any of the deposits that you might see are related to a particular valve.


The following was a question I received about the plugs, etc. I'm adding it here in hopes that it may be of some use to someone doing a similar search:
Quote:
Originally Posted by cobalt
Quote:
Originally Posted by 396chevelle
Cam lift is .510/.495 duration 287/304 degrees---lobe center 110 dgrees-----overlap 19.00 degrees. Air gap intake and the jets on the primarys are 78/78 secondaries are 86/86. The picture's in my post that you were looking at was the one on the left was at idle and the one on the right was at mid range. I haven't done a WOT yet. Due to the motor being new. I was trying to get a few miles on it first, but I guess since it was dynoed before I dropped it in the car it will be fine. I was also worried about the A/F being to out of wack before I jammed on it. I've got it set at highest vacuum at about 7 in. hg. 3/4 turns out on all 4 mixture screws.
The plug on the right looks fine. The plugs will color more evenly after the engine has some run time on it- that gives the rings a chance to fully seat and the blow-by that's present (to some extent) on any new build will be reduced. I see no reason by what you've shown to change the heat range.

Lean is fast. Too lean is detonation, and too rich is slow and soggy. Do not arbitrarily add jetting to the primary side. Why not? If the plug color is good, adding fuel will net you nada except it'll burn more fuel. Let the plugs and/or an air/fuel ratio meter tell you what the engine needs.

In another thread you mentioned you have a heavy smell and eye watering exhaust. This is caused by incomplete combustion and is an indication that the initial timing needs to be increased to then be able to close the primary throttle blades to get back out of the transition circuit more than you now are. The idle and transition circuits are active at idle, but you want to limit the transition circuit's contribution to the idle air/fuel mixture.

If you feel the timing is optimum for the engine, you can (instead of advancing the initial timing) open the secondary throttle blades a touch (to allow more idle air into the engine) to offset closing the primary blades down by using the curb idle speed screw. This can (in some cases- all engines are different) help the idle smell you're getting.

There may be a need to change to a smaller idle air bleed at some point, but for now try the things above first. If you see no improvement you can go from there.

The most important thing to have control of before running WFO is the total timing. There can be NO DETONATION while at WOT under load- like running at the strip. If you have 37 degrees total- and you're positive that there's no timing "creep" occurring at higher RPM, you'll be fine as long as you run good gas as insurance.

The timing creep I mentioned can be easily checked by winging the throttle while using the timing light. The idea is to verify there's no advance above the RPM that you believe the timing is all in by. If you give it a quick rev to see 5000 RPM and you see no added advance, you can be sure the mechanical is all in.

In cases where the carb is too small, there can be manifold vacuum at WOT that could in some cases cause a vacuum advance to start adding timing at WOT. Being as your carb is a 850, this shouldn't be a problem. But if you're using a vacuum advance, you don't want more than 10-12 degrees, and you'll want to tune the tip-in point to match the engine.

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Old 01-06-2012, 09:55 AM
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Quote:
Originally Posted by 396chevelle
I'll pull the plugs this weekend and put it a new set. When I pull the new set to see how there doing I'll mark them and let you know which cylinder they were firing in! Thanks for the info. WOT or Cruising speed?
Cruising at this point we're just trying to get a look at the general health of each cylinder. WOT is tougher test to do it properly I'll quote Cobalt's earlier input which is:

"If you want to get a better idea of the air/fuel ratio, you have to do a "plug chop" to show you the color. This would be done at the RPM/load where you were interested in checking, i.e. if you want to know what the a/f ratio looked like at WOT, you'd run it at WOT to do the chop. Same thing for mid-range cruise, etc. Idle mixture can be checked in various ways, but before doing any of that, the timing should be dialed in. Depending on the cam you might need quite a bit more initial timing than would seem 'normal'."

The WOT is harder to do as you need to put in a fresh set of plugs when ready to perform the test, run it for the test then kill it at the top end and coast down out of gear, then pull the plugs. They need to be inspected under a bright light and with magnification as unless there is something really, really off the insulator color changes are very subtle and difficult to see. Somewhere in some old hot rod book there is a picture of a guy doing this; holding a plug in one hand while using a hand held lighted magnifier in the other with an eye ball to the lens.

Your issues if there are any seem more general where the WOT test is after just what's happening at a specific place.

Also, keep in mind that often when a plug gets carboned up it never recovers. My wife's Sportster is like that, if she leaves the choke on too long it fouls the plugs and no amount of cleaning and reuse brings them back, you just toss 'em and restart with new, clean porcelain. This is why I want you to just put a fresh set of plugs in and put some miles on them, so we start with a clean slate to read from.

Bogie
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Old 01-06-2012, 01:04 PM
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Quote:
My wife's Sportster is like that...
Now if that ain't cool... Bogie, do you ride too?

Sorry for the OT post. To make up for it I'll throw in a link:

HERE is a site to give you the basics of plug reading.

And http://www.empirenet.com/pkelley2/sparkplugreading.html

I have a link to an article on plug chops that I cannot locate just now, but a search will provide plenty of info on the how-to part of it.

That is a good point about plugs- often they will not recover from fouling, despite being cleaned. They may be good enough to get some idea if used for reading after being cleaned, but it's better to bite the bullet and use a new set.

Back when plugs were fiddy cents apiece there was no reason not to replace them all after a run. Nowadays, they're still cheap- at least the regular type plugs are, but there are some plugs (like platinum/iridium) that you just cannot toss that easily. Even replacing a few plugs w/new ones and reading just them will suffice once you know what cylinders you are concerned with, or which cylinders are running rich or lean due to intake distribution, etc.

After reading them they can be used for normal use once things are dialed in.
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Old 01-06-2012, 01:56 PM
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Originally Posted by 396chevelle
There Champions
I think that's half the problem. i never had good luck with Champion plugs.
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Old 01-06-2012, 06:29 PM
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Quote:
Originally Posted by cobalt327
Now if that ain't cool... Bogie, do you ride too?

Sorry for the OT post. To make up for it I'll throw in a link:

HERE is a site to give you the basics of plug reading.

And http://www.empirenet.com/pkelley2/sparkplugreading.html

I have a link to an article on plug chops that I cannot locate just now, but a search will provide plenty of info on the how-to part of it.

That is a good point about plugs- often they will not recover from fouling, despite being cleaned. They may be good enough to get some idea if used for reading after being cleaned, but it's better to bite the bullet and use a new set.

Back when plugs were fiddy cents apiece there was no reason not to replace them all after a run. Nowadays, they're still cheap- at least the regular type plugs are, but there are some plugs (like platinum/iridium) that you just cannot toss that easily. Even replacing a few plugs w/new ones and reading just them will suffice once you know what cylinders you are concerned with, or which cylinders are running rich or lean due to intake distribution, etc.

After reading them they can be used for normal use once things are dialed in.
Below is a picture of the Chrome Show, I was trying to sell it on consignment this last summer so this is picture of it on the local dealer's floor. It didn't sell I've just got too much in it to ask a discount price and the current economy won't support the cost recovery I need, so I just decided to keep it. Besides at my age just how long can I keep long distance riding.

It's a 2000 Heritage Softail Classic. I put a big bore kit on it to boost it from 88 to 95 inches. The Harley sometimes troublesome chain cam drive is replaced with S&S gears and cams. The carb is a HSR 48mm Mikuni, Flatslide with a Screaming Eagle ignition module. The HD 5 speed is replaced with a Baker 6 speed. The pipes are Bub Straight Aways. I added a tach and put chrome lowers wind deflectors on the front. Installed Screaming Eagle foot boards, brake and shifter controls, and highway pegs. This is my first bagger which, like a station wagon, was something when I was younger I said I never own. But old age makes its own dictates so I bought this and sold my old David Mann style bobber/chopper hard tail a while ago, I did keep my Yamaha Virago/V-Max mix as I've got way too mucho bucks in that for what I can get for it. At least my health is still good enough to ride and build things. I'm thinking if I can get away for the better part of a month that I'll ride 4 Corners next summer on the Softail.

I put an Odyssey battery in the FLSTC last summer as ever since I put the 95 inch kit on it and did not adjust the compression for the extra inches it's been difficult to start as if it doesn't fire on the first couple turns, the battery dies and has to go on the charger, last one being an Interstate. I swear now the engine is running just as you touch the starter switch.

While I thought I'd sell it and get an injected model last summer, I discovered I've just got too many big bucks in it, just can't sell it for anything close to recovering some of the cost of the goodies, everybody wants it for Blue Book or less, so I'll keep it. My wife rides a 2003, 1200 Custom which is a nice bike I can really flick it around which while the FXSTC weighs in at 700 plus pounds before I'm on it, it is surprisingly maneuverable but nothing like the Sportster.



Bogie
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Old 03-07-2012, 03:21 PM
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Absolutely beautiful bike, Bogie-love the pipes, and I'll bet it has some beans! I have a Harley too, and we're getting close top riding season around here! Can't wait-

edit: oops, I didn't see that this Post was a few Months old-sorry!
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Old 03-07-2012, 03:29 PM
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Originally Posted by 35WINDOW
Absolutely beautiful bike, Bogie-love the pipes, and I'll bet it has some beans! I have a Harley too, and we're getting close top riding season around here! Can't wait-

edit: oops, I didn't see that this Post was a few Months old-sorry!
I'm still reading things as they drop in regardless of age. Thanks, put a lot of effort into that thing. Decided to keep it instead of starting over.

I'm ready for riding season, it's been a long winter.

Bogie
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