I'm changing out my spark plugs in my 53 chevy 1/2 ton with 216 engine and pulled out AC 104 plugs. Been looking for replacements but am finding no luck. Went to Napa store and the only thing they could come up with are the AC Delco M8 plug. Am I ok with this plug? I didn't order them yet because i wanted to do a little more investigation work and came to this board because of all the great advice I've received in the search forums. Thanks in advance 53joe
I'm confused, but then again, that's nothing new. Looking through various reference material, it shows that the AC 104 was used in 216 engines until '48. '49 and later 216's used the AC 44-5 plug. The biggest difference between these 2 plugs is that the 104 is a 10 mm thread plug, whereas the 44-5 is a 14 mm plug. I wonder if a previous owner might have replaced the original engine with an older version. Do you know the serial # of your engine? That would help identify the model year of the engine. Irregardless, if it takes 10 mm plugs, I'm pretty sure that Bosch still makes one that is a replacement for the AC 104. Hopefully, a less confused poster can shed some more light on the subject.
Yes Ken you are right. This truck was my dad's and he did have to replace the engine and I believe from the serial numbers it's a 1950 engine. I will check with bosch and try to match up that little plug. Thanks, I'm impressed.
' Peanut ' Spark Plugs If you cannot find the correct 10MM spark plugs by looking up '41 ~ '46 Passenger cars , use NGK copper cored ones , forget about platinum crap as they run too cold and will foul in older engines quickly . Champions ? not for free , no thanx . Remember to gap them to .035" . If it's time for spark plugs , it's also time to adjust the valves , dwell and ignition timing.....
Must be a "Blue Moon"! I very seldom disagree with anything Nate says! But once in a blue moon, I question his infinite wisdom! According to every old shop and/or owner's manual I've read in the last 2 days on the subject, the AC 104 (10 mm) plug should be gapped at .040. I totally agree on .035 on the others. Gotta go! I hear thunder! And there's not a cloud in the sky!
We Agree As I always say to run the spark plug gaps as wide as you can without misfire ~ thing is , most folks want to run .025" ~ .027" and argue when I say .040" + . So , I just say .035" most of the time and they try it and like the improvement in running . When HEI first came out they'd tell us to run .055" ~ .060" .
.035 was the standard back in the day and still holds true for your 6 banger. My Dad always said nothing but AC plugs for a Chevy.
I Assume........ ...You all know that ' AC ' (as in AC DELCO) stands for Albert Champion.... yes , that same one .
....and why are Albert's initials on the plugs? As I recall, the story goes: Albert didn't like the "Champion plugs", made by his brother(?), so he started his OWN company, AC. And I must agree, I was brought up a GM man, and only an AC plug will do in a GM engine. I don't know WHAT kind of plugs you put in a F^&D, because I have never owned a F^&D product, ever! There was however, that dark period of time when I had a D^%GE minivan in the driveway.....
With the petronics system Autolite 303 gapped to 35, is another plug one could run. Or just run the 303's if you can not find the AC of your liking. Also look into our host, if that does not work then the truckshop might be of some help, but first try our host to locate your needs.
