Plugs - porcelain white as new??

[pcguy]

Have been messing with this 350 now for some time and I may have gotten the high heat problem squared away – will be making another test later this week and will be reporting the results in the thread that I started on that issue.

Before I run the next temp test (at 60-65 MPH it runs hotter than I’d like to see it at about 215-225 depending on the ambient temp) there is one other anomaly that raised it’s ugly head and like everything else, it doesn’t make any sense.

Thought I had the carb and timing issues worked out and I even went so far as to take the carb apart and check everything again. Have recently changed from 45RTS to 44RTS because of a couple of specs on the porcelain of one of the spark plugs – just one of eight, the others were ok. Also backed off the timing just a bit down to 30 all in at 2800 and 13 initial. During my last temp test (need to go to a freeway and the nearest one is 20 miles), the results of which continued with 220 temps. On the way back I disconnected/plugged the vacuum advance expecting some difference – same temps.

Here’s the hard part – up until this trip/test the plugs looked just a tiny bit too white, but they were generally tan overall – this is the 44’s. Then after returning from the above test (remember the vacuum was disconnected for about 20 miles), I pulled two of the plugs and what do you know, the porcelain was as white as new out of the box, but the electrode was colored properly with just the flat spot showing signs of heat - the part at the turn was good which is what I was hoping to have happing with the 44's.

One would think that having reduced timing while cruising would cause the plugs to go darker.

This concerns me primarily because nothing else changed except the ambient temp was a little hotter at mid-nineties than any of my previous tests.

Anyone experience this before?

[monzajer]

Here's a couple links for you(there are more):

http://www.atlanticjetsports.com/_techtalk/00000005.htm

http://www.theultralightplace.com/sparkplugs.htm

http://www.bing.com/images/search?q=col ... &FORM=IGRE

Google or Bing "colors of spark plugs"

Hope this helps.

Cheers, Jer

[pcguy]

Thanks Jer, have read the plugs previously and aware that they shouldn’t be totally white (although reports differ somewhat on that). Just trying to figure out what caused the color to change when nothing else changed.

It did just occur to me that one potential difference was that I mistakenly put in a half tank of 87 octane the fill-up previous to the fill-up just before this happened. But it was quite diluted by the time I made this observation.

Concerned because I would like my next temp test to resolve all issues???

Thanks again,

Nick

[cammerjeff]

Just curious to see if you are reading you plugs after idling for some time, or shutting down at cruising RPM? If you are looking for a specific rpm mixture reading, make sure you run the engine at that RPM for a 10 seconds or so, shut the engine down, and then read the plugs. Otherwise you are reading mostly idle mixture on your plugs. It can be a Painful experience attepting to read plugs properly. I know and have the burn scars to prove it!!!!

Any more I just have a Bung welded into each side of the exhaust system, and temporarily install a Wide Band air fuel mixture gauge to test the Mixture, they are a lot cheaper than they used to be, and they are the only way to accurately test the A/F ratio at various RPM. Just my Opinion.

http://www.glowshiftdirect.com/air-fuel-gauges.aspx

http://www.jegs.com/p/Holley/Holley-Com ... 6/10002/-1





I have had several frustrating conversations about plug reading with racers at the track. They Idle back to the pits, let the engine cool down, confirm that they have a good idle mixture, (not that they are very lean at higher RPM's)

Good Luck and Let us know how it goes.