desoto1939 Posted March 13, 2021 Report Posted March 13, 2021 I know there has been a lot of owners that hate the Champion Sparkplug the J11 plugs for our flathears. But I was doing some lookinf for anther owner and noticed something very informative in my 1937-53 Napa Parts cataog that lists the various parts used for all major cars. They have a section for Chrylser, Dodge, Desoto and Plymouth. So this is what they lsit as replacement plugs for Dodge: 1945-54 Champion J8, AC 37-54 #43, Auotolite 37-54 A-7 Plymouth same as above for Dodge but 37-49 AC #45 50-54 AC 46 Desoto 46-54 Champion J8 AC 37-53 #46 Autolite 37-53 A7 Chrysler 35-42 6-8 cylinder Champion J11 46-54 6 or 8 J8, AC 35-51 6 or 8 #45 52-53 #46 Autolite 35-51 6 or 8 AL7 53-53 6 or 8 B-9. I do have an autolite catalog a Blue Crown Catalog and a Chamipon Catalog to cross reference against In my Autolite Sparkplug Catalog that covers 1930-39 There is a chart to compare the Autolite, AC and Champion plugs and the Champion J11 is not even listed as being a plug to cross over from an Autokite, The Champion J8 is listed to be equal to the Autolite A7 In my Blue Crown The Champion J11 is equalt to the Autolite A9 which is a hotter plug. So maybe w have all been using the incorrect Champion Plugs with the J11 plugs that people have been told to use. Ant I think the J8 was replaced with the J8C plug. This is a good topic for discussion. I am using the Autolite A9 plugs in my 1939 Desoto. Rich HArtung desoto1939@aol.com 1 1 Quote
sidevalvepete Posted March 13, 2021 Report Posted March 13, 2021 Good stuff Rich. Will look carefully at this. Thanks ? Quote
TodFitch Posted March 14, 2021 Report Posted March 14, 2021 When I first got my '33 way back in the 1970s the documentation I found said that a Champion J-11 is what I should use. So I used that for decades and many thousands of miles with no issues. A few years ago, based on discussions on this forum, I tried the recommended AutoLite plug. After a few thousand miles it started running poorly. So I switched back to Champion J-11 and haven’t had an issue I could trace back to them. Maybe it is just my engine. Maybe it is/was my imagination. Whatever. By the way, J-11 is the old number. I believe the current Champion number for that plug is 511. Quote
desoto1939 Posted March 14, 2021 Author Report Posted March 14, 2021 55 minutes ago, TodFitch said: When I first got my '33 way back in the 1970s the documentation I found said that a Champion J-11 is what I should use. So I used that for decades and many thousands of miles with no issues. A few years ago, based on discussions on this forum, I tried the recommended AutoLite plug. After a few thousand miles it started running poorly. So I switched back to Champion J-11 and haven’t had an issue I could trace back to them. Maybe it is just my engine. Maybe it is/was my imagination. Whatever. By the way, J-11 is the old number. I believe the current Champion number for that plug is 511. I did a search on Champion 511 and below is what I found on the web: Quote
Worden18 Posted March 14, 2021 Report Posted March 14, 2021 I just pulled a set of sooty J11s out of my 48 B1C. They were rusty and had been in there for some time. Replaced with NGK BR6S. The J11s looked horrible, but it has to be my b&b carb that helped get them that way. Quote
JBNeal Posted March 14, 2021 Report Posted March 14, 2021 When I first started my '48 1/2 ton in '96, I used the J8 plugs that were in it for a few thousand miles. Those J8s were made in the early 70s, Dad put them in when he drove the truck til he parked it due to a variety of issues + not having time to work on it in the late 70s or 80s. I replaced them in 2002 with new J8s as those decades old plugs were worn to the nubs, but the new J8s fouled up in a hurry in weather below 60°F. Around 2004, I changed to the Autolite 306, and carbon fouling went away. I did not have the time to figure out what was going on in the flathead, but about the same time, I had a Champion grenade in my '92 John Deere 425 Kawasaki 2cyl, another Champion grenaded in a Troy-Bilt rototiller with a Briggs & Stratton, and had heavy carbon fouling in Grandma's '86 Diplomat. Replaced all those plugs with NGK and AC, and those problems went away. Champion wasTHE spark plug for a very long time, but these quality issues in the early 2000s soured me on them...does Champion make a better plug now? Does compression play a role in carbon fouling? I recall how surprised Dad was when I told him that smooth running flathead I had revived after sitting for 20+ yrs was using the same Champion spark plugs that he put in it before I was born...I do not know if that kind of quality is even possible these days from Champion, as I believe their materials cost cutting to improve profitability has been miscalculated to their reputation's detriment. But if the Champion J8 is made nearly as good now as it was in the early 70s, I would run them again in a heartbeat...cold startups were less than 10 seconds, wear was good, any fouling was serviceable within reason, a good value if the quality has improved. 1 Quote
Sniper Posted March 14, 2021 Report Posted March 14, 2021 Can't say about Champions, but the Autolite 306's fire up within 2 revolutions. Almost instant. Been running both brands over the years and never really had a problem. Only plugs I ever had an issue with was Bosch platinum, the ceramic around the center electrode fell apart on two plugs causing my 413 to ping. But I got into the habit of new plugs every year on my carb'd cars so that might account for my lack of issues. 1 Quote
desoto1939 Posted March 14, 2021 Author Report Posted March 14, 2021 Glad to see and read some of the comments and experiences that people have had with the champions. It seems as if the older good plugs were of good quality but as the years have gone by their quality control has Gone with the Wind, sorry for the pun, could not resist. I am always on the lookout for Autolite A9 original plugs and or the 306 Plugs for my 39 desoto. I have had the A9's in the car for over 5 years at least. According to the Champion Catalog the Champion J8 was replaced with the Champion J8C a plug that is used in a lot of lawn equipment. Rich Hartung Quote
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