msarnold1990 Posted July 16, 2021 Report Share Posted July 16, 2021 Hi All, My mechanic recommended I change the fuel filter, oil filter and spark plugs on my 48 D24, which I did this evening. After replacing everything, the engine idled very rough. Being a rookie, I thought I may have had the connections criss crossed on two of the spark plugs. Now it only turns over. So I'm assuming I need to switch the two connections I changed? Any ideas what may cause the rough idle? I made sure to gap the plugs as directed. The old plugs were ancient, black and the ceramic cracked in spots. Quote Link to comment Share on other sites More sharing options...
maddmaxx1949 Posted July 16, 2021 Report Share Posted July 16, 2021 (edited) You can check that the right wires are going to the right plug with the firing order 1-5-3-6-2-4.... If I remember correctly the 1 fires with the rotor in the 7 o'clock position so make sure that one is at no. 1 spark plug wire. Secondly, which plugs did you go with? I've read on here there are a few that can cause rough running. Edited July 16, 2021 by maddmaxx1949 1 Quote Link to comment Share on other sites More sharing options...
msarnold1990 Posted July 16, 2021 Author Report Share Posted July 16, 2021 I replaced what was there which was the Autolite 295. I'll check the distributor cap tomorrow. Quote Link to comment Share on other sites More sharing options...
Loren Posted July 16, 2021 Report Share Posted July 16, 2021 Get an ohm meter and check the resistance of the wires. No more than 10,000 ohms. The wires are when old can be damaged just by moving them. That was probably your rough idle. Quote Link to comment Share on other sites More sharing options...
dwest999 Posted July 16, 2021 Report Share Posted July 16, 2021 You may need new wires. I just bought a set from Brillman (link https://brillman.com/product/1948-1954-plymouth-spark-plug-wire-set/). Also, you might want to consider a set of non-resistant plugs. Quote Link to comment Share on other sites More sharing options...
maddmaxx1949 Posted July 16, 2021 Report Share Posted July 16, 2021 22 minutes ago, dwest999 said: You may need new wires. I just bought a set from Brillman (link https://brillman.com/product/1948-1954-plymouth-spark-plug-wire-set/). Also, you might want to consider a set of non-resistant plugs. I believe 295's are a non-resistor plug. I know a couple of the members here run 306's which are a resistor type. Quote Link to comment Share on other sites More sharing options...
allbizz49 Posted July 16, 2021 Report Share Posted July 16, 2021 Did you do each plug and wire one at a time? If not, start with what madmax said. Also, make sure the wire ends are pushed all of the way into the cap and snug on the plugs. Quote Link to comment Share on other sites More sharing options...
desoto1939 Posted July 16, 2021 Report Share Posted July 16, 2021 Test to see if the sparkplugs wires are leaking. Start the car at night time in your garage, open the hood, turn off all lights look at the sparkplug wires as the car is running if you see blue flashes or arcs from the wires then they are really bad and need to be replaced. When replacing the wires do one wire at a time so number 1 on the cap to number 1 sparkplug. Also pull the wire out of the cap to see if there is corrosion where each wire connects to the cap. Also check the inside of the cap to see if there is worn spots on the contact. If the car has sat this long could also be a rotor, points, condensor. I have a 39 Desoto and I use Autolite A9 sparkplugs for 35 years. Might also want to consider getting an NOS breaker plate for your distrbutor. All of the interanl and cap/rotor/condensor will be based off of the number on the red plate on the side of the body of the dizzy such as IGS or IAT-xxxx. Tell us the number of the dizzy and then we can tell you the exact Autolite parts to purchase. send me an email to Desoto1939@aol.com Rich Hartung Quote Link to comment Share on other sites More sharing options...
chrysler1941 Posted July 16, 2021 Report Share Posted July 16, 2021 So you have eliminated the carb as a source of fault? ignition and carburetion issues are very similar and can be hard to diagnose one from the other. Quote Link to comment Share on other sites More sharing options...
msarnold1990 Posted July 16, 2021 Author Report Share Posted July 16, 2021 I have not. I got the plugs in correctly. I think it may be the carburetor Quote Link to comment Share on other sites More sharing options...
Plymouthy Adams Posted July 16, 2021 Report Share Posted July 16, 2021 its all a conspiracy.....global warning is your problem....they doing this to kill off cars running carburetors......electronic controlled cars can auto compensate for all these conditions.....the 2040 bug is built in and if you don't run electric....you going to be walking......? 1 1 Quote Link to comment Share on other sites More sharing options...
keithb7 Posted July 16, 2021 Report Share Posted July 16, 2021 Good opportunity here to remind folks to blow out dirt or any other objects out of the recessed area in the head, around the spark plugs before removing them. 1 in a million chance something sizable could drop down in the spark plug hole. It happened to me. A small screw. Previous owner never found a screw when it fell. When I was new to the car I pulled the spark plugs. It dropped in. There is very little space between the head and valves. Another 1 in a million chance, the screw wedged itself between the valve and the head. The valve bent. You wanna talk about rough running? A compression test proved it. Off came the manifolds and head. Followedby a full new set of valves, a grind and lap. All good after that! Lol. Surely not your problem sir. Just a friendly little reminder. A 15 min job is only precious moment from a near catastrophe. Want to see? ? Quote Link to comment Share on other sites More sharing options...
allbizz49 Posted July 16, 2021 Report Share Posted July 16, 2021 How did it run before the plug and wire change? Quote Link to comment Share on other sites More sharing options...
chrysler1941 Posted July 16, 2021 Report Share Posted July 16, 2021 10 hours ago, Plymouthy Adams said: its all a conspiracy.....global warning is your problem....they doing this to kill off cars running carburetors......electronic controlled cars can auto compensate for all these conditions.....the 2040 bug is built in and if you don't run electric....you going to be walking......? I hope I die of old age before forcing me to drive a battery car 1 1 Quote Link to comment Share on other sites More sharing options...
Plymouthy Adams Posted July 16, 2021 Report Share Posted July 16, 2021 we all hope to die of old age.....really old age......stoke out at 96 powershifting into 4th just as you cross the trap...... 1 Quote Link to comment Share on other sites More sharing options...
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