Read these plugs please. Timing

[BitchinZ]

I have an 83 L28ET with Z31 ECU in a 77.

 

These plugs are new, 0 miles,  just idleing.  Gapped at .42.  My timing is at 25 BTDC with TPS plugged in.  They have a yellowish varnish (fuel?)  The car starts fine and runs good for about 30 seconds then starts stumbling badly.  It also gets hot really quick. 

 

Is this caused by my timing being too advanced? Stock for the 83 I thought was 24 +/-3. 

 

Should I be setting timing for the Z31 ECU?  I have a new set of NGKs gapped to .39 to use. 

 

Thank you

 

 

[thezguy]

Get some better pictures your focus is out of wack

[seattlejester]

Reading plugs really only tells lean or rich, and that is a rough estimate at best. And your focus is indeed out of whack. You can determine the lean or rich better with a wideband which would not be a bad investment. 

 

Set timing to your ignition system/engine. The base timing is what the engine wants to run at. If it is running hot you can turn retard the ignition a bit, but that is a roundabout guess work method. At the minimum, get values for exhaust temp to see if it is out of range and adjust timing down if that is how you want to do it.

Edited June 27, 2014 by seattlejester

[Xnke]

Reading plugs doesn't even tell you lean or rich, really. All it tells you is how hot or cold the combustion chamber is, and those plugs look "ok" for a factory tune.

 

If the engine is running hot, your timing is not correct. Check your damper, make sure it isn't spun. Make sure you have both the Z31 MAF, ECU, and trigger wheel in the distributor. I've never done that particular swap but I would imagine you need to know what the stock timing is for the Z31 ecu in it's home configuration.

Edited June 29, 2014 by Xnke