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Spark plugs black

3170 Views 114 Replies 9 Participants Last post by  ericnova72
Hello all,
Can you take a look at these plugs and tell me what’s going on? I just installed them and have only idled this freshly rebuilt and already broken in cammed 383 stroker. The strap is shinny black. The center electrode is flat black. These are brand new Autolutes 3924. I was fighting a very rich stinky idle with this AED Holley 750 DP, but fixed it and trashed the old fouled plugs. I’m running MSD 6A and a lot of timing at idle. 36 degrees.
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Discussion Starter · #41 ·
Awesome info. My main issue that caused me to author the post before this was that very very smelly smokey eye burning exhaust. My clothes would smell the rest of the day. Electronically bumping the initial to 40 even 45 cleaned it up and I was able to close down both primaries and secondaries. They had both been open over a full turn just for 900 rpm with the usual 18-20 degrees initial. Now I it’s just the black plugs and carb backfire issue. Rich eye burning smell is 90% gone.

You mention misfire. these Autolites 3924’s seemed to have a slight misfire from the second I installed them. Just slightly. Prior to that I was running accels with not enough reach. They were covered in soot due to the whole initial smelly exhaust issue but they never misfired. I’m switching them for the FR5’s soon and starting over with all the above advice given in this thread.
 

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Your builder is mistaken. He's blowing smoke up your as. Stop asking him questions.
Verify TDC with a piston stop and the damper.

Set timing. 36 if fine for now.
I'd expect 20 initial, all at 3100, 34-36 total.

Try this.

1. Set primary to 0 idle rpms
2. Set secondary to 800-1000 rpms
3. Set primary for additional 400, total rpm should be
at 1400 rpms
4. Blip throttle to 2100-2500
(NO MORE)
Wait 3 seconds the. Blip again to 2100-2500
5. On the second blip the rpm should drop to
1400rpm... exactly!
6. If under 1400 rpm turn idle mixture screws in 1/8,
7. If over 1400 rpm turn idle rixture out 1/8
8. Set this process twice.then start over at #1.
9. Do complete process 2-3 times.
10. Close both front a rear evenly, so the rear is doing about 60 percent of the idle control.

If that doesn't help than I suspect late cam timing.
 

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Discussion Starter · #44 ·
Just to be clear. Step 1 is primary throttle blades closed all the way? That’s what you mean by zero? On step two the engine should be idle if on secondary air only??
 

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Discussion Starter · #46 ·
I stumbled on something today right before I was going to start your idle process.

Due to all the backfires I checked the power valve out of curiosity. Just for the heck of it I checked the rear power valve plug. That round gasket was torn. The chamber in the main body behind the power valve plug was full of gas. I figured that was the issue all along, BUT…. This baseplate has secondary power valve vacuum reference hole. The hole in the body goes to nothing. 100% blocked.

I was so happy to find this hoping this was the issue all along, only to be disappointed when I saw no hole. Could the fuel gotten sucked into the intake some other way?
 

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Discussion Starter · #49 ·
Something is not right here. Seems things are getting worse fast. I tried the process above and started by letting the engine warm up. It was more stinky than ever. Eyes burning bad. I reved it up a few times and a very rich fuel smell and white smoke out the exhaust. Spark plugs black and wet with fuel. I wonder if this carb has an internal leak.
Could it by my ignition? 6AL and MSD blaster 3.
 

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Check simple stuff first.
Float levels still good?
Float bowl screws tight?

Any chance you could try another carb?? Any carb that would bolt to the manifold, regardless of the CFM rating....just to tell if it is carb or ignition.

Your 6AL a digital, screwpot adjusters?? or an older analog, chip style box?
 

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Discussion Starter · #51 · (Edited)
I started fresh. Simple stuff. Fuel fresh, gas tank new, all lines new, new Aeromotive pump and regulator, and filters, psi at 5.5 per in car gauge and separate external gauge to confirm.

bowls have sight glasses and set spot on.

float bowls good and tight. No external leaks.

no other carbs. I wish. Apparently nobody in my town is into cars. No dynos. No speed

new 6AL unit and MSD blaster 3 coil.

i ran a few tests. All I could think to do. I put my timing light on every spark plug wire one at a time. Everything worked fine but the light would slow down as I revved the engine up. Like it was starting to skip sparks. Could this be ignition related?

plugs are black and wet with fuel.

front driver side idle mixture screw not as responsive as the other 3. Leak?
I noticed the intake gasket under the 1 inch spacer was wet with fuel on the outside. As if it seeped all the way through. A little gas puddled on the bottom of my intake.

I read that black smoke is rich and white smoke is raw fuel.

lastly, I did not know what else to do so I used my laser pointer thermometer to check each header tube. Left side header was hotter than the right.

could this be a defective coil? Bad MSD box? Internal carb leak?
 

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Also, I am told that some models of dial back timing lights have trouble with some performance ignitions (I assume these are the electronic dial back type with timing dial back displayed electronically). Non dial-back lights and timing tape is preferred, but I can attest the old chrome Craftsman dial back lights with a knob to turn are fine. I also have a Flaming River one-wire timing light (non dial back) but its not very bright.

Sent from my moto g power using Tapatalk
 

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Discussion Starter · #57 ·
As far as timing pointer and TDC goI drove myself crazy making sure it’s dead on.

Here goes: I spoke to Skip White’s people to make sure the balancer that came with the 6 inch rod 383 stroker internal balance rotating assemble.

I called the company that makes the balancer to make sure it was correct and to confirm what pointer i needed to use.

I called my engine builder who swore up and down the cam was properly degrees and balancer lined up to TDC.

i checked it myself with a piston stop like 5 times. I marked the balancer with a silver sharpie and measured in between the lines with a soft seamstress tape measure.

I used two different timing lights. None were dial backs. Timing dead on

I checked that the distributor was not 180 out.
plug wire routing. You name it. I spark tested the MSD 6a and coil.

it seems to be dumping fuel. white exhaust smoke all the time at and rpm. Not blue. Burns eyes so bad if you are near the car. The higher the rpm, the higher the load, more smoke. Like a stuck injector.

bottom of the intake on the left, lower side, full of gas. I burned through 5 gallons of gas in a few days. It’s so weird. I just don’t get it because it idle and drives fine.
 

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Hello all, Can you take a look at these plugs and tell me what’s going on? I just installed them and have only idled this freshly rebuilt and already broken in cammed 383 stroker. The strap is shinny black. The center electrode is flat black. These are brand new Autolutes 3924. I was fighting a very rich stinky idle with this AED Holley 750 DP, but fixed it and trashed the old fouled plugs. I’m running MSD 6A and a lot of timing at idle. 36 degrees. View attachment 627506 View attachment 627505 View attachment 627504 View attachment 627503
Running rich check carb setting s
 

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Sounds like the timing pointer is correct.

I think you have more than one problem. Ignition timing with your new distributor is one of them. Flooding is the other.

You can easily check the timing problem by switching to the old HEI. Just like you could check the flooding problem with a different carb.

You shouldn't have to jack with a new AED carb custom made for your vehicle. If you do, then you need to send it back to them for repairs

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I’m still running breakin oil. I will drive it around. These are autolite 3924. I was thinking of switching to NGK. Where could the oil be coming from? The engine was just built by a reputable builder.
The rings need to seat. Drive it a couple hundred miles and see how they look. They look fine for a newly rebuilt engine especially running at idle. I rather expected to see them blacker than that.
 
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