What do my plugs say?
Thread Starter
Holley HP EFI w/TPI
Joined: May 2009
Posts: 553
Likes: 0
From: Kanata ON
Thread Starter
Holley HP EFI w/TPI
Joined: May 2009
Posts: 553
Likes: 0
From: Kanata ON
Race Director
Joined: Sep 1999
Posts: 11,361
Likes: 383
From: Plano TX
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Thread Starter
Holley HP EFI w/TPI
Joined: May 2009
Posts: 553
Likes: 0
From: Kanata ON
Lean would surprise me, I'm using the Holley HP EFI, it should be tuning itself 
R45S are the plugs, are they the right ones for this engine (1970 corvette engine, TPI manifold)
R45S are the plugs, are they the right ones for this engine (1970 corvette engine, TPI manifold)
Race Director
Joined: Sep 1999
Posts: 11,361
Likes: 383
From: Plano TX
I don't see anything that would indicate it's lean. There is soot on the last thread of the shell. The center electrode should stay white/light grey. Many people still expect a tan color, but that was from lead. Some premium pump gas will make a reddish color though.
I'd replace with the same plug.
I'd replace with the same plug.
Melting Slicks
Joined: Mar 2002
Posts: 2,164
Likes: 7
From: Beringen
Go 1-2 ranges colder and see if the discoloration on the groundstrap moves towards the middle of the bend. To me it looks like the plugs are running hot. I don't see any signs of it being too lean.
The one with the indication 'bad' looks as if it has had pre-ignition signs.
Note : an FI system tunes based on the O2 sensor. There are other things that can disrupt the info coming from the O2 sensor like exhaust leaks, missing etc.
The one with the indication 'bad' looks as if it has had pre-ignition signs.
Note : an FI system tunes based on the O2 sensor. There are other things that can disrupt the info coming from the O2 sensor like exhaust leaks, missing etc.