Help reading plugs...

[MNwe4]

Can I please get some opinions on what these plugs are telling me? The more discolored plugs are in the rear cylinders. Cyl 5 looks the worst. As far as I can tell I have the rest of the car sorted after the latest rebuild. Just swapped plugs today before I get into the tuning stage and want to be sure I'm not overlooking anything. So far I've only done a bunch of cruising and under 20 psi pulls.

 

[Chuck Leeper]

In order to read plugs, you need to start w/ a fresh set, make a pull, read them. Idle time, cruising time, on a set makes them pretty much useless for a read.
Take a look here.
http://www.wallaceracing.com/plug-reading-lm.html

 

[MNwe4]

Hi Chuck, I guess I should say that I'm not trying to read them in the conventional way to tune, but rather am curious why there's a color gradient from front to rear. I own a power plate, but it is not installed on the car. That said, I'm not sure what the darker color means, lean/hot or rich. Thanks for the advice.

 

[RmvBfrFlght]

Plug #5 has splotches of oil on it. This can be an indication that oil is being pulled through the PCV system.

Plug #2 looks a bit scary, the tiny black specs is usually a sign of detonation. Plus it looks like that cylinder is possibly lean and running hot. Same for #1, although the picture of that plug is out of focus so hard to tell.

Plug #3, not sure but appears to be getting a constant, light supply of oil, maybe a valve stem seal issue.

Give 50 miles or so on the new plugs then pull them and take another look. Note that since the heads are aluminum, don't R&R the plugs until the engine is cold.

RemoveBeforeFlight

 

[MNwe4]

Plug #5 has splotches of oil on it. This can be an indication that oil is being pulled through the PCV system.

Plug #2 looks a bit scary, the tiny black specs is usually a sign of detonation. Plus it looks like that cylinder is possibly lean and running hot. Same for #1, although the picture of that plug is out of focus so hard to tell.

Plug #3, not sure but appears to be getting a constant, light supply of oil, maybe a valve stem seal issue.

Give 50 miles or so on the new plugs then pull them and take another look. Note that since the heads are aluminum, don't R&R the plugs until the engine is cold.

RemoveBeforeFlight

Are you reading the plugs left to right as the're titled in the photo? Just making sure we're talking about the same ones since I'm trying to learn.

Does anyone think there would be a benefit to putting the rjc powerplate back on the car? My set up is this: 70mm throttle body, stock plenum, 1/2" spacer plate, stock intake, gn1 aluminum heads. The intake and heads were also ported at champion and the plenum looks to have light machining work as well. Thanks for the help.

 

[belsie]

The way I understand it is: stock plenum's shortcomings are reason enough for RJC plate. As you move thru the various tests & processes you need to try all combos at your disposal........................

 

[RmvBfrFlght]

Are you reading the plugs left to right as the're titled in the photo? Just making sure we're talking about the same ones since I'm trying to learn.

That is what I was going by, hopefully I didn't get any mixed up.

RemoveBeforeFlight

 

[MNwe4]

Thanks for the responses guys. I'm going to throw the plate back on and see if it makes any difference.