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Old 05-31-2024, 07:24 PM
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How do I know which plug has an extended tip

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Old 05-31-2024, 10:35 PM
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Originally Posted by 64speed View Post
How do I know which plug has an extended tip
On AC plugs it will have an "S" suffix. Example: R45TSX (R=resistor, T=taper seat, S=extended tip, X=wide gap)

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Old 05-31-2024, 10:54 PM
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How long has the pictured plug been in there? You said a while back that you were taking the car to get the carb dialed in correct? Put some new plugs in it. Drive it a while and report back. I have never seen a plug that bad that wasn't oil or gas fouled. I can't believe that people are saying this is from idling or slow driving. There's something else going on here. If your plugs look that bad, from idling and slow driving, your carb is screwed up. What about your PCV line? Have you looked to see if it's sucking excessive oil?

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Old 06-01-2024, 01:59 AM
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I haven’t had the carb tuned yet. It is definitely fuel fouling. That runs great at cruise and wot but has a very inconsistent idle.

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Old 06-01-2024, 07:05 AM
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In your post number 1979 ( 5,01, 2024 ) from your many years long string of post about this car you stated that you now had 3000 miles on the car and where happy with the way it was running.

It seems like that was not so now, or over 3000 miles ago you did not know what you where talking about!

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Old 06-01-2024, 07:11 AM
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Originally Posted by 64speed View Post
I haven’t had the carb tuned yet. It is definitely fuel fouling. That runs great at cruise and wot but has a very inconsistent idle.
Fix the carb before you start worrying about reading plugs. The hottest plug in the world isn't gonna compensate for drowning in gas. You're also at risk of wiping out your rings from washing the cylinder walls with gas. You can't put the cart before the horse.

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Old 06-01-2024, 08:05 AM
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The plugs are never going to come out looking brand new on a hot rodded carbed engine. This isn't EFI and electronic timing control.

On top of that todays pump fuel does not color plugs like the old leaded fuel did so the part throttle stuff can't really be judged accurately. Todays fuel is a little on the sooty side. I can show you plugs that are idling with a 14:1 AFR with a bunch of low speed cruising and they still come out looking fairly black around the ring with some black on the porcelain, and about the only thing that isn't black is the very tip of the ground strap and electrode. That's just the way these things are with large overlap camshafts, and it doesn't mean it's harmful or out of tune.
You would need to have it really stupid rich to wash rings down. In fact I've had engines that want to idle in the low 13's for AFR, which blackens the plugs, and run like that for years and 10's of thousands of miles with no ill affect, no ring wash, none of that. I think that gets exaggerated on the internet as people get so used to EFI and super lean AFR's they think everything should look that way.

The only way you'll lean out the idle and part throttle cruise to have really clean plugs on a carbed engine and still have the thing idle and part throttle cruise without hiccups is on a fairly stock engine that has no camshaft overlap, and dial in a fair amount of timing. Then you can lean it out to a point plugs start looking cleaner at idle and still have a strong idle, good vacuum, and good drivability without the issues that come with something too lean. You likely aren't going to get there with a hot rod 455 running a cam that has some overlap if you want it to idle decently and drive well.

With all that said, yeah the picture shows plugs that are black, but not fouled. Could they be a little cleaner? Probably. But it's likely going to take more than just trying to lean out the idle mixture and even then the plugs still aren't going to look pristine.

If it were mine, a 455 with a RAIV camshaft I set up like this. I typically would dial in 14 initial and have 20 centrifugal in the distributor. I would modify the vacuum advance to give me about 12 degrees additional, with the slot welded to limit it, and the spring adjusted to start around 6 inches and all in by 10 inches. I then run that on manifold vacuum which should give me about 24-26 degrees of idle timing because this engine should be making about 13 inches of vacuum with a nice strong idle. These cams are not that big at all in a 455 providing you have enough compression and the ICL is set correctly. I make them idle with practically no lope detectable and don't need Rhoads lifters to tame it. These things are way out on a 113 LSA and only have 230 @ .050 intake duration, they just aren't that radical at all.

What this will do is give you enough idle timing that you can start to run a pretty lean AFR at idle if you want. You won't be able to have a lean idle AFR with very little idle timing, it just won't have the nice drivability that it should. It's going to need some idle timing. Most of these issues are timing related and not so much carb related.
The timing alone should help to clean things up but I'll mention now, todays ethanol fuel stoich is 14:1 and going a bunch leaner really is of no benefit and gets to a point of diminishing returns, idle quality starts to suffer, vacuum signal starts to drop, and you may even notice part throttle drivability won't be as good. Depends on how far you go with it and how your engine wants to respond to the changes.

Long winded post but gives you an idea what to expect.

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Old 06-01-2024, 08:20 AM
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Originally Posted by Formulajones View Post
The plugs are never going to come out looking brand new on a hot rodded carbed engine. This isn't EFI and electronic timing control.

On top of that todays pump fuel does not color plugs like the old leaded fuel did so the part throttle stuff can't really be judged accurately. Todays fuel is a little on the sooty side. I can show you plugs that are idling with a 14:1 AFR with a bunch of low speed cruising and they still come out looking fairly black around the ring with some black on the porcelain, and about the only thing that isn't black is the very tip of the ground strap and electrode. That's just the way these things are with large overlap camshafts, and it doesn't mean it's harmful or out of tune.
You would need to have it really stupid rich to wash rings down. In fact I've had engines that want to idle in the low 13's for AFR, which blackens the plugs, and run like that for years and 10's of thousands of miles with no ill affect, no ring wash, none of that. I think that gets exaggerated on the internet as people get so used to EFI and super lean AFR's they think everything should look that way.

The only way you'll lean out the idle and part throttle cruise to have really clean plugs on a carbed engine and still have the thing idle and part throttle cruise without hiccups is on a fairly stock engine that has no camshaft overlap, and dial in a fair amount of timing. Then you can lean it out to a point plugs start looking cleaner at idle and still have a strong idle, good vacuum, and good drivability without the issues that come with something too lean. You likely aren't going to get there with a hot rod 455 running a cam that has some overlap if you want it to idle decently and drive well.

With all that said, yeah the picture shows plugs that are black, but not fouled. Could they be a little cleaner? Probably. But it's likely going to take more than just trying to lean out the idle mixture and even then the plugs still aren't going to look pristine.

If it were mine, a 455 with a RAIV camshaft I set up like this. I typically would dial in 14 initial and have 20 centrifugal in the distributor. I would modify the vacuum advance to give me about 12 degrees additional, with the slot welded to limit it, and the spring adjusted to start around 6 inches and all in by 10 inches. I then run that on manifold vacuum which should give me about 24-26 degrees of idle timing because this engine should be making about 13 inches of vacuum with a nice strong idle. These cams are not that big at all in a 455 providing you have enough compression and the ICL is set correctly. I make them idle with practically no lope detectable and don't need Rhoads lifters to tame it. These things are way out on a 113 LSA and only have 230 @ .050 intake duration, they just aren't that radical at all.

What this will do is give you enough idle timing that you can start to run a pretty lean AFR at idle if you want. You won't be able to have a lean idle AFR with very little idle timing, it just won't have the nice drivability that it should. It's going to need some idle timing. Most of these issues are timing related and not so much carb related.
The timing alone should help to clean things up but I'll mention now, todays ethanol fuel stoich is 14:1 and going a bunch leaner really is of no benefit and gets to a point of diminishing returns, idle quality starts to suffer, vacuum signal starts to drop, and you may even notice part throttle drivability won't be as good. Depends on how far you go with it and how your engine wants to respond to the changes.

Long winded post but gives you an idea what to expect.
Maybe I never had a big enough camshaft to cause this. IDK. But I've had some pretty big cams. All I run is an HEI and they look completely normal. Plugs should not look like the one he posted in my opinion. He admits that the thing is idling inconsistent. So are you advising him to leave it as is? How do you know the plug posted isn't fouled? Look like $h!t to me. He says it's dry. I say B.S. What's that stuff that looks like oil wicked all the way up the threads?

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Old 06-01-2024, 08:54 AM
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Thanks so far to the people who haven’t been rude. The car runs great…except the idle is inconsistent, so I pulled a plug and that’s what I got. I know that you’re supposed to be able to tell something about the health of the engine by the plug color so I asked. No need to lambast me. As far as the miles I am on my second engine if you recall so I am just now passing the point that the last one failed. This is not a weekend cruiser. I drive it almost everyday, to the doctor, to Walmart, to Arby’s at 10 last night. I just need it to be as “right” as it can be.

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Old 06-01-2024, 09:28 AM
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Maybe I never had a big enough camshaft to cause this. IDK. But I've had some pretty big cams. All I run is an HEI and they look completely normal. Plugs should not look like the one he posted in my opinion. He admits that the thing is idling inconsistent. So are you advising him to leave it as is? How do you know the plug posted isn't fouled? Look like $h!t to me. He says it's dry. I say B.S. What's that stuff that looks like oil wicked all the way up the threads?
I am only laying out the other things that affect this. We can only guess, we are not there. If I had the car in front of me I could tell you in 10 minutes what it needs.
My best guess from doing this for a living is that the timing probably isn't optimized on this combo, who knows where the ICL is. That affects idle quality tremendously. Possibly the carb could use some changes. In a nut shell It could probably be cleaned up some but I doubt completely just given the circumstances.

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Old 06-01-2024, 09:40 AM
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Thanks so far to the people who haven’t been rude. The car runs great…except the idle is inconsistent, so I pulled a plug and that’s what I got. I know that you’re supposed to be able to tell something about the health of the engine by the plug color so I asked. No need to lambast me. As far as the miles I am on my second engine if you recall so I am just now passing the point that the last one failed. This is not a weekend cruiser. I drive it almost everyday, to the doctor, to Walmart, to Arby’s at 10 last night. I just need it to be as “right” as it can be.
What is your initial timing? Have your checked your carb float levels front and rear? Do you have a vacuum gauge? If so, you need to check what your idle vacuum reading is. You'll need a helper for this. Warm the engine up. See what the vacuum is in gear. You may have too large a power valve for your vacuum. While it's idling in gear, look down the primary venturis and see if fuel is dripping from the primary boosters. If it is, there are a couple of things that can cause that. If all that checks out, you can use the vacuum gauge to dial in your idle mixture screws. I'd be glad to talk to you by phone if you'd like some help. Sorry if I have been rude. I just felt strongly that your plugs aren't normal. That you needed to get on the right track.

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Old 06-01-2024, 09:44 AM
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Originally Posted by Formulajones View Post
I am only laying out the other things that affect this. We can only guess, we are not there. If I had the car in front of me I could tell you in 10 minutes what it needs.
My best guess from doing this for a living is that the timing probably isn't optimized on this combo, who knows where the ICL is. That affects idle quality tremendously. Possibly the carb could use some changes. In a nut shell It could probably be cleaned up some but I doubt completely just given the circumstances.
Agreed. Maybe we can focus on helping him verify timing, carb, PCV, possible vacuum leak, exposed idle transfer slot, etc. that may be screwing his idle up. I really think this engine needs some help.

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Old 06-01-2024, 09:56 AM
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Idle quality is usually near one of the first things that is worked out after cam break in
its natural to float back and forth between initial and total timing idle speed and mixture until everything is in a happy place then drive the car a bit and do it all over to look for a gain in performance

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Old 06-01-2024, 11:11 AM
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If the car is tuned up enough to make short trips like what was described I doubt the tune is that far off. With a pretty big CSA port and a 300+ cfm head running errands to Walmart, I think you can expect a standard plug to have some deposits like that.

I would change to a plug in a similar heat range that has projection and run it again. Larry’s post has that pretty much spelled out. Sounds like you maybe could use help picking the next plug you should try. The NGK I linked would be a little better, NGK has a plug with projection that would be better yet, but I would have to look up the numbers. After you swap plugs check the vacuum advance is adding enough timing to make sure that wasn’t part of the issue.

The letter after the heat range is the projection on Champion plugs. I think you would need an “M” instead of the “Y”. Last letters in the part number would be MC instead of YC.


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Old 06-01-2024, 11:34 AM
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Can someone with a similar setup post a picture of their plugs for reference? I'd like to see it for comparison.

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Old 06-01-2024, 12:27 PM
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That's just normal for a pig rich, out of the box Holley carb.
Here's where you need to start: https://documents.holley.com/199r11202.pdf

If you find the engine does not respond to idle mixture changes, then you may have a condition where the engine wants more idle air than than provided. By turning the idle speed screw to increase the idle speed (allow more air at idle), the primary side throttle plates are tipped further towards opening and more of the transfer slot is exposed which introduces more fuel and creates a rich idle and often an off-idle stumble.

At this point, take the carb off, turn it over and see how much of the transfer slots are exposed. The transfer slot, under ideal conditions will show as a square below the throttle plate. If it shows more as an elongated slot, you have excessive amounts of fuel entering the engine at idle. The fix is to back off the idle speed screw until the transfer slot is back to a square, then add additional through the secondaries. There is a throttle stop screw in the baseplate that you can turn to adjust the throttle plate position at idle. 1/4 - 1/2 turn in is typically all it takes to open the secondary throttle plates slightly to add more air.

Here is a good explanation of the methods to introduce more idle air without adding fuel via the transfer slots https://www.enginelabs.com/engine-te...tle%20opening.

While some may not consider your RAIV cam big, it has enough overlap to depress manifold vacuum causing you to dial in more primary throttle plate opening in order to idle. Dive in and tune the carb. If you follow the secondary throttle plate adjustment to add idle air and verify correct choke and idle mixture settings, you should see an improvement in idle quality and cleaner plugs.. If you can't get it idling and running more cleanly following the steps outlined, I would be very surprised.

Forget about the alternative method of drilling idle air bypass holes in the throttle plates as also shown in the article. That is typically reserved for engines with huge camshafts and very low manifold vacuum that are untuneable at idle by other means.

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Old 06-02-2024, 12:45 PM
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Don't you E-Heads. NGK plugs. Heat range 7

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Old 06-08-2024, 05:47 PM
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Just thought y’all would find this funny. The erratic idle was the pcv inlet at the back of the carb was loose and wiggly in the base. I got another one from Holley and it cured the erratic idle like that.

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Old 06-08-2024, 06:21 PM
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Well that fix should help the carb not sence a lower vacuum level which would make it run richer than need be all the time.

It’s good that you found that.

Here’s a picture of plugs out of a forum members car .
His handle is the Soup man.

The motor is a 428 with iron # 47 heads on it that I ported and he runs a good size hydro roller cam .
The motor is run on pump gas and plugs have 100 miles on them.

This is what I would expect out of any street strip motor that’s built right and tuned correctly.
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Old 06-08-2024, 08:23 PM
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Yes those are my plugs, they have some full throttle blasts to almost 6000 rpm, plus significant highway miles. My older set of plugs looked almost as good with a lot of idling and highway with 3000 miles on them, just more tan colored. I like the AC 45 plugs since they seem a little hotter. Plus you can get them brand new on Amazon right now for $2.72 per plug.

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