harmony Posted September 1, 2019 Report Share Posted September 1, 2019 I've read that a lot of you guys are using Autolite 306 spark plugs. My 251 flathead has 295 plugs and although they look fine gap wise, I thought I would give the 306 a try to see if there was any difference. I'm trying to get my car to not run so rich on start up and I thought maybe a hotter plug might make a difference. But that's beside the point of this posting. So I came across something interesting. I went to the parts store to get them and as you know they come in a pack of 4 in a box. So I got one box plus two more in their own separate individual boxes. As I pulled them out I noticed that the 4 in the group box had a bright steel base, while the 2 separate plugs had a black steel base. The boxes looked virtually identical except for one line on the box that said where they were made. The bright steel ones were made in Mexico and the black steel ones were made in China. I'm curious if there might be any difference in the performance of the plugs over time? Quote Link to comment Share on other sites More sharing options...
Plymouthy Adams Posted September 1, 2019 Report Share Posted September 1, 2019 only performance difference SHOULD be the ability to withstand corrosion over time and heat cycles of the two different finishes...think four of one and two of the other would be noticeable at even a casual glance...kill the deal for me.... Quote Link to comment Share on other sites More sharing options...
harmony Posted September 1, 2019 Author Report Share Posted September 1, 2019 Yes they are noticeable at a casual glance. But how many guys open all the spark plug boxes at the parts counter to inspect them before purchasing them especially since the boxes look the same. Quote Link to comment Share on other sites More sharing options...
Plymouthy Adams Posted September 1, 2019 Report Share Posted September 1, 2019 yeah....maybe return them and buy a set of eight....after 3 tune up, your fourth is free with the unused 2 per set......looks good on paper, can't see it from my house as they say.....lol I believe the counter guy would work with you on this... Quote Link to comment Share on other sites More sharing options...
desoto1939 Posted September 1, 2019 Report Share Posted September 1, 2019 I just purchased on ebay a set of autolite 306 sparkplugs for 25 with fress shipping and they came from Andy Bernbuam and all 6 had the chrome base. 4 in pne box and 2 is individual boes. Look under 1935 - 1954 Chrysler desoto sparkplugs. Rich Hartung desoto1939@aol.com Quote Link to comment Share on other sites More sharing options...
greg g Posted September 1, 2019 Report Share Posted September 1, 2019 As Mike Jagger said, I want them painted black. Tape them and rattle can them satin black. Quote Link to comment Share on other sites More sharing options...
harmony Posted September 2, 2019 Author Report Share Posted September 2, 2019 Good idea Greg. The bright steel ones stick out like a sore thumb. I had already installed them right away so returning them isn't an option. But country of origin will be a good thing to watch out for next time I purchase plugs. Quote Link to comment Share on other sites More sharing options...
greg g Posted September 2, 2019 Report Share Posted September 2, 2019 Well, so far I have 40,000 on my set of AC 45's I put in after my rebuild, so it may be a while till you need to replace these... Quote Link to comment Share on other sites More sharing options...
9 foot box Posted September 3, 2019 Report Share Posted September 3, 2019 I had the same experience, they reordered and I got all the same. 306's are resistor plugs with a .035" gap. It won't run right, with the .028" gap, that the non-resistor 295 requires. I tried it. It didn't start as quickly, was the first thing I noticed. Your start up rich problem is probably related more to the choke operation. Pull the air filter and observe the action of the choke valve when the starter is energized. The choke valve should close. As the engine warms up, the choke valve should open gradually to the wide-open position. From the book, it tells you how to adjust it, too. I read in the Technical Tip's, I think, that a two pump on the throttle before starting cold, was a proper practice. It works for me. But I have manual choke and only partially use it. Quote Link to comment Share on other sites More sharing options...
Tom Skinner Posted September 4, 2019 Report Share Posted September 4, 2019 One can also set their 592 plugs to .035 Gap as well as they come set at .030. Any Resistor Plug should be set at .035, or reset them Quote Link to comment Share on other sites More sharing options...
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