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Dumb spark plug question


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Okay here's the question, I have a 1948 Dodge d24, but it has a 1957 DeSoto 230 in it, last time I ordered spark plugs, I got champions from RockAuto and just ordered them for a 48 Dodge, I was going to go to the auto parts store and pick up some new plugs today along with a few other things, and just out of curiosity I looked up spark plugs for 1948 Dodge, and for 1957 DeSoto both with the 230, and they show two completely different Champion plugs, one says it takes a 511 and the other one says it takes an 841, I always thought flatheads took the same plug, I'm trying to figure out the difference, wondering if anyone has dealt with this before

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31 minutes ago, Plymouthy Adams said:

heat range due to increase in compression

Okay so now I'm even more confused, I just looked up the spark plugs again, and the one for the 57 is an 841, it says the heat index is 8 of 15, and the 511 for the 1948 says it's 11 of 15, so that means the earlier plug is hotter

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42 minutes ago, Plymouthy Adams said:

heat range due to increase in compression

I've always ran champions in all my Mopars, but I see that a lot of people on this page run the Autolite 306 in their flatheads, so I guess I'm going to give that a shot

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Had excellent results with ac 45r.   The same set has been in my 56 plymouth 230 since the rebuild 45000 miles ago. I have checked the gap 3 or 4 times.  When I last gapped them they still looked like they did at 5000 miles. I set my timing by vacuum gauge, according to the timing marks it running 5 or 6 degrees btc.  My compression ratio.is

8.7 to 1 with milling the head and decking the block. My last set of champions in the 218 were j10.  They put on a neat light show after dark.  Spark traveled down carbon tracks on the outside of the porcelain caused by carbon blowby from leaking when they partially fires on power stroke.  Never tried autolite in the Plymouth, but have spoken to others that run and like them.

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50 minutes ago, greg g said:

Had excellent results with ac 45r.   The same set has been in my 56 plymouth 230 since the rebuild 45000 miles ago. I have checked the gap 3 or 4 times.  When I last gapped them they still looked like they did at 5000 miles. I set my timing by vacuum gauge, according to the timing marks it running 5 or 6 degrees btc.  My compression ratio.is

8.7 to 1 with milling the head and decking the block. My last set of champions in the 218 were j10.  They put on a neat light show after dark.  Spark traveled down carbon tracks on the outside of the porcelain caused by carbon blowby from leaking when they partially fires on power stroke.  Never tried autolite in the Plymouth, but have spoken to others that run and like them.

My car set for roughly 50 years, the motor was supposedly rebuilt and I got a piece of paper with the car that says it was rebuilt and a lot of good records on the car even including compression and everything taken before I got the car, I put points, plugs condenser, rotor cap wires, the basic tune-ups in it, haven't taken it out on the road because I had the interior completely out of it and redoing it, but I drove it around the yard sitting on a cinder block it ran fantastic, checked everything out compression was still exact same numbers as on the list that I got with the car, put the seats back in the car a few days ago and took it up the block ran fantastic, started it up yesterday, ran like absolute dogshit, like it was running on three cylinders, and smells like raw gasoline pouring out the exhaust, checked to make sure the float wasn't sticking on the carburetor , pulled out the plugs, they don't look wet or anything, but I've heard a lot of bad things about Champion plugs lately, not to mention the only points that I could get had that stupid plastic cam on them, I did a compression test, still has the exact same compression everything else is good, so I'm pretty sure I have a defective plug, but I'm also going to switch out the points again, and see what happens

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1 hour ago, Sniper said:

If the plugs you have been running were working ok I'd just buy new ones of those.

 

 

The problem is, they only lasted about 3 miles, I got rid of the Champions today, and put some Autolite 306 in, and a new set of points, and she's running great again, ready for our first car show on Saturday

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Should have replaced one ignition item at a time to know what caused the problem...was it points or plugs.

Then reported it.

I would think it was the modern day points.

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1 hour ago, Dodgeb4ya said:

Should have replaced one ignition item at a time to know what caused the problem...was it points or plugs.

Then reported it.

I would think it was the modern day points.

I know, just got so much going on, I didn't want to spend extra time on the car, trying to have it running and driving for our first car show Saturday, otherwise I would have done one at a time, but my guess is probably those points, even though they looked like brand new when I took them out, they make everything out of cheap garbage these days

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