Replaced plugs and coil packs

[Ohjai]

I replaced the plugs and coil packs this morning in my 91 Coupe.  My what a difference it made.  This car was a bit sluggish compared to my 91 Convertible, I just thought is was due to the extra miles on the car,.

 

The plugs that I removed were gapped at a minimum of 0.080" and I had a bit of a problem getting the wires off.  I cleaned the ignition board with DEOXIT.  All in, I was done in a couple of hours.  I am waiting for the new plug wires to show up today, and if it isn't raining or too hot, I will change them out today.

 

Edited August 6, 2023 by Ohjai

[Ohjai]

The plug wires got here today and I replaced them.  This car with 78,000 miles drives great and accelerates faster than this old man needs to be accelerating.  It was a fantastic day for me.

 

[ship]

That old spark plug looks downright nasty!  It's always nice to have a car that goes faster than you want or can handle.

[Ohjai]

The gap on one was 0.090", the others was around 0.080".  should be 0.60".

Edited August 7, 2023 by Ohjai

[2seater]

One thing I have wondered about is, does it take more energy to fire the two spark plugs in series or not? We have a waste spark system, so the circuit has two spark plug gaps to cross at essentially the same time. One is under compression and the other exhaust, so the voltages required are not equal, but the head scratcher is, are the two gaps added together, or not? The internet seems to have little agreement. If the wide gap requires higher voltage, which takes a bit of time to build up to ionize the gap, closing the gap, would have the tiny effect of advancing the spark timing??

[Ohjai]

Interesting thought 2seater.  I believe you mean the two plugs are in parallel since they fire at the same time.  Is the air/fuel mixture more conductive than than the remaining exhaust gas?  If so, perhaps the air fuel spark fires a bit ahead of the exhaust plug giving a slightly hotter spark.  If this is true, would the faster firing leave enough energy at the wasted plug to jump the 0.060 gap.

[DAVES89]

The water here is a little deep here for me, but I gap my plugs at 0.055. I figure they will run a bit longer at optimal spark.

[2seater]

This is the circuit diagram for a four cylinder but the principle is the same. It appears the current flow is in series where one plug fires forward and the mate fires in reverse. I always have a hard time getting my head around the fact that the plug center and side electrodes are isolated from each other and the only way for current to flow is by jumping the gap, no matter which way it is going.

I would guess if a hypothetical runner can jump a ten foot gap, they could also jump a five foot gap, and more easily? But what if there was a series of gaps to jump, maybe fifty or a hundred? 😖