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Black & White Electrode- Spark Plug Reading

Mike67

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I need some help deciphering a couple of my plugs. So yesterday I pulled my plugs in order to replace the inner springs after breaking in the cam and there were 3 that some unusual patterns on them. It was like a perfect deciding line that parted the electrode, half of it had typical carbonate & the other half was a clean as it was when installed.
I've never seen that before, any ideas what that means?
Motor is a 440/Holley Terminator & dual sync distributor, RPM heads, base timing is &18°/32° compression is approximately 10.5, 93 octane, cam is 545 lift 241/247° @.050.
 
These plugs were only in for the break-in process???

Don't bother looking at them. I went threw this with my brand new motor as well, was freaking out cause they all looked so weird and different. Your cam might be "broken-in" but the rest of the motor is still working it self in. Unless the motor seem to be running poorly , don't worry about anything yet would be my suggestion.

Get some run and more importantly DRIVE time on the motor. Check again with 500+km on it .
 
Once the engine has had some load on it I would look at the plugs again but give it a bit if time to settle down.
 
Perhaps a few pix to help with visualization of your issues or questions.....a pix is worth a thousand words....
BOB RENTON
I meant to grab some before I left the shop, but totaly forgot.
They look pretty good, not lean or rich, just have of the electrode ( ceramic holding the electrode) is perfectly white much like a two tone paint job. The parting line is almost perfect...never seen that before in my life!
 
I agree. Plugs can look off until the engine gets some regular drive time. Mixture variations and how the plugs are indexed in the chamber can cause that half clean/half colored look (so I've been told).
Your efi isn't dialed in yet and the temps can do funny things on first fire-up also.
Are you running an RPM intake or a true single plane?
 
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I agree. Plugs can look off until the engine gets some regular drive time. Mixture variations and how the plugs are indexed in the chamber can cause that half clean/half colored look (so I've been told).
Your efi isn't dialed in yet and the temps can do funny things on first fire-up also.
Are you running an RPM intake or a true single plane?
Thanks, I went ahead and used the RPM with a 1" spacer. I've read so many conflicting reports that the efi doesn't like dual plane manifolds & that you need to mill out a 1x2" section out of the divider for a better signal. I figured the spacer would accomplish this instead of messing with it.
The car fired right up idled well had to adjust my target afr as it would lean out on occasion going to 14.6, it currently stays in 13.5 range.
 
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Thanks, I went ahead and used the RPM with a 1" spacer. I've read so many conflicting reports that the ego doesn't like dual plane manifolds & that you need to mill out a 1x2" section out of the divider for a better signal. I figured the spacer would accomplish this instead of messing with it.
The car fired right up idled well had to adjust my target afr as it would lean out on occasion going to 14.6, it currently stays in 13.5 range.
Ok. From what I've noticed from friends that run EFI, the RPM intakes work just fine. I was only asking because there will still be the normal distribution issues and that could account for some plugs to read a little differently than others, but no big deal.
 
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