Dino Diaries - Nov 19, 2024 - Change Spark Plugs, PVC Plug and add some 100 Octane Gas

[Jason Edge]

I have been having a blast with my 64 Coupe de Ville Dino the last couple days, now that the recored radiator is in, and decided to change plugs last night, then the PCV valve, then thought I would treat it to some (5 gallons) of 100 Octane gas from a nearby station that I found selling it a few weeks back.

PLUGS: I use Autolite 85 plugs. I use to use fancy multi-top platinum and other plugs but ended up with these for daily driving. Seem to be in the correct heat range and give good performance. I do have a set of NOS AC 44 (part # 1559492) on the shelf I may use one day if I take it to the grand national. To be honest I have been nervous about using them since reading the late John Washburn's Self-Starter article from way back where he had tested a rather large # of NOS plugs only to find that a good % failed. I would feel better if I had these tested.

GAP: Since I haver the Pertronix III ignition and Pertronix Flamethrower III ignition coil sending out a higher than stock voltage (they claim up to 45K volts), I gap my plugs around .040", that would be a bit more than the .035" stock gap, and less than the max .045" gap. I have been reluctant to go more or less as this seems about right.

Gas & Octane Rating:  If you go to our Octane Rating Information help page and see the math converting from todays ((R+M)/2) method, Cadillac recommended a minimum of around 94.5 Octane for our 10.5 to 1 compression engines.   If you remember the days of High Test gas in the 1960's and 1970's advertised as 100 octane, that would have been the higher ("R" research method).  The Motor method is often about 10 less, so using today's standard the old High Test was actually about 95 --> ((100+95)/2).   

Keep in mind that 93 octane (well even 91) seems to run fine in our cars. I always run 93 but decided to treat my tank with 5 gallons of 100 octane last night.   Doing my math (20 gallons of 93 octane + 5 gallons of 100 octane) = about 94.6 octane.  That 100 octane gas --> $9.99 a gallon! But this is Dino and it was his night!

Here is a picture after changing the plugs and PVC Valve. If good weather I would usually rather work at night outside with a headlamp on as I can actually see better than in the full sunlight or in the garage.