Spark Plugs Condition

[MKossor]

A long time E-Timer user shared this photo of his plugs removed for the first time after approximately 8K to 10K miles of use. They look pretty good to me compared to spark plug debug photos I've seen but wonder what more experienced eyes see.

[George House]

They look very good to me considering the stated mileage. Not sooty but dry electrode area. Something I do and would recommend for these plugs is high speed wire brush the rusty metal below porcelain. Then mask porcelain. Finally, spray clear lacquer or enamel on the bright metal. With moderate usage it’ll stay as-new appearing for years.

[Moxie26]

It seems that these spark plugs have been working pretty good. White gray electrodes indicate to me a good firing plug due to plug quality and electrode gaps, good electrical values in the coils, good E-Timer commutator, and a driver's sense of good fuel mixture. Very dark or flaky deposits would indicate some problems with oil burning due to worn piston rings or extra clearance in valve guides , or just running rich fuel mixture.....My experience with running the E-Timer is simply the first quality item that contributes to the best running engine possible due to improved ignition. Taking the plugs out for the Gap check , the electrodes have always been a light gray color... Rarely did I have to readjust back to 0.025" after brush cleaning. Engine was rebuilt around 7,000 mi ago and I really don't see any problem with oil burning. My experience with the E-Timer gives an easier starting engine, a perkier engine, more precise timing, and helped adjusting fuel mixture a bit leaner to get more miles per gallon.... And the plugs stay relatively clean from all of the above. Enough talking, I'm going for my first cup of coffee this Sunday morning. . I'm anxious to read what others have to post .

[TXGOAT2]

They look good to me. It would be helpful to know if they are arranged in order. Two of them, 2nd and 4th from left, appear to have a very light soot coating, which may indicate a slight leak at one of the intake manifold ports. Many later engines will run plugs very clean. I don't think that low speed, low compression T engines run plugs as textbook clean as a tight, high compression, high speed engine will. A T engine running without an air cleaner may accumulate deposits of fused-on dust on the ground electrode. This can be very hard to remove, since solvents have little or no effect on it. Dirty oil will lay more deposits on plugs than clean, high quality oil.

[TWrenn]

3,000 miles on Heinze coils. Look okay to me!

[TXGOAT2]

3K since new? Electrodes look eroded. Deposits probably average for a T.

[Moxie26]

Pat .... Possibility it could have been a used and recycled older spark plug matched up with a newly rebuilt Heinze coil. There are T guys I know that clean up old Champion X plugs that have visibly worn electrodes , gapped at 0.025" , and engine runs smoothly.

[Moxie26]

TWrenn... Running Heinze coils and E-Timer ?

[MKossor]

Thank you for sharing your comments. I have a few more details to share on the pictured set of spark plugs:

- The plugs were originally gapped between 0.030" and 0.035".
- All plug gaps were found to measure over 0.035" when some misfiring was noted
- All plugs were re-gapped to 0.032"
- The engine does have good compression on all cylinders
- Mixture is carefully monitored which yields a bit over 20MPG

[TWrenn]

3K since new? Electrodes look eroded. Deposits probably average for a T.

No no...sorry. This was since last check. They have 12,000 miles on them since new and yes I'm watching the electrode wear. Probly invest in a new set next season. The car runs so good atm I hate to spend the money....yet!

Thanks for the observation.

[TWrenn]

TWrenn... Running Heinze coils and E-Timer ?

Nope. Running my beloved TW timer and it is the best I've ever seen.

[TWrenn]

Okay I should read all the posts b4 replying!
This particular car consistently gives 24 mpg with the stupid top down...and 22 with it up and the rear curtain rolled up to mitigate wind resistance.

[Moxie26]

TWrenn .... Good running !

[TXGOAT2]

As I recall, it was often recommended to replace spark plugs at 10,000 miles well into the modern era. A T engine with the ignition system in good condition is less demanding on the spark plugs than later engines with higher compression. I believe a T engine would do best with a gap around .030 to .032, but if you start on magneto, .025 to .028 is probably best. A hot magneto will permit a wider gap, which is good as long as you don't get high speed misfire or hard starting. Over .032, you are probably pushing your luck with the coil windings, and the same may be true when using plugs with badly eroded electrodes at narrower gaps. A wide gap can allow secondary voltage to get very high in the coil. Having all 4 plugs in the same condition with identical gaps contributes to smooth running by helping keep coil dwell time consistent between cylinders.