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1972 Duster 340 #8 cylinder won't fire #337204
06/03/09 02:29 PM
06/03/09 02:29 PM
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Maryland
reno340 Offline OP
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Help! I have a 1972 Plymouth Duster 340 w/ factory electronic ignition. My # 8 plug won't fire. I replaced it w/ Bosch Platinum plugs, New cap and rotor and a new wire set. I took that plug and switched it w/ #2's plug and #8 cylinder still does not fire. I switched back to the old cap and rotor in case the new one was faulty. I first noticed it when I Put the exhaust back on the open headers (Hooker Comps) and one tail pipe sounded different, that exhaust was nuch cooler and there was more condensation comming out of that pipe (clear water not antifreeze) and you could smell a raw gas like smell comming out of that pipe. I found out it was the one when I squirted each header tube w/ a spray bottle set in stream and #8 did not sizzle off like the others. Can some one help me fix this? I don't have a lot of money to throw at this in parts or tools.




"There are only three real sports, Mountain climbing, Bull Fighting and Auto Racing. The rest are just games"
- Earnest Hemmingway


If you can't run with the big dogs, stay on the porch!!

https://www.youtube.com/watch?v=_xQJtN1_6DU
Re: 1972 Duster 340 #8 cylinder won't fire [Re: reno340] #337205
06/03/09 02:37 PM
06/03/09 02:37 PM
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albany ny
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LOW or no compression on 8?

Re: 1972 Duster 340 #8 cylinder won't fire [Re: reno340] #337206
06/03/09 02:38 PM
06/03/09 02:38 PM
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Maryland
reno340 Offline OP
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BTW. I am no mechanic so you will have to give me more complete instructions than others. Also, no buddies to help me bump it over or other 2 man jobs. I do have hand tools and a timing light but have never used one. (got it for free)



"There are only three real sports, Mountain climbing, Bull Fighting and Auto Racing. The rest are just games"
- Earnest Hemmingway


If you can't run with the big dogs, stay on the porch!!

https://www.youtube.com/watch?v=_xQJtN1_6DU
Re: 1972 Duster 340 #8 cylinder won't fire [Re: reno340] #337207
06/03/09 02:57 PM
06/03/09 02:57 PM
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Gainesville,FL
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goldmember Offline
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Remove number 8 plug wire from the plug. Insert a screw driver into the plug wire boot until it's securly touching the metal terminal. Hold the handle of the screw driver with the shaft close to a metal surface on the valve cover,head,etc,non painted surface. Have someone spin the engine over for 10 seconds. You should see get a spark. If so the problem is with something mechanical,I'd lean toward very low compression on the number 8 cylinder. Do a compression test of that cylinder.

Re: 1972 Duster 340 #8 cylinder won't fire [Re: goldmember] #337208
06/03/09 04:35 PM
06/03/09 04:35 PM
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Maryland
reno340 Offline OP
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Quote:

Remove number 8 plug wire from the plug. Insert a screw driver into the plug wire boot until it's securly touching the metal terminal. Hold the handle of the screw driver with the shaft close to a metal surface on the valve cover,head,etc,non painted surface. Have someone spin the engine over for 10 seconds. You should see get a spark. If so the problem is with something mechanical,I'd lean toward very low compression on the number 8 cylinder. Do a compression test of that cylinder.





What should it read?


"There are only three real sports, Mountain climbing, Bull Fighting and Auto Racing. The rest are just games"
- Earnest Hemmingway


If you can't run with the big dogs, stay on the porch!!

https://www.youtube.com/watch?v=_xQJtN1_6DU
Re: 1972 Duster 340 #8 cylinder won't fire [Re: reno340] #337209
06/03/09 04:39 PM
06/03/09 04:39 PM
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Grand Prairie,Texas
stumpy Offline
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At least 110lbs

Re: 1972 Duster 340 #8 cylinder won't fire [Re: stumpy] #337210
06/03/09 05:48 PM
06/03/09 05:48 PM
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Maryland
reno340 Offline OP
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How do you do a compression test?


"There are only three real sports, Mountain climbing, Bull Fighting and Auto Racing. The rest are just games"
- Earnest Hemmingway


If you can't run with the big dogs, stay on the porch!!

https://www.youtube.com/watch?v=_xQJtN1_6DU
Re: 1972 Duster 340 #8 cylinder won't fire [Re: reno340] #337211
06/03/09 05:55 PM
06/03/09 05:55 PM
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Gainesville,FL
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Compression gauge(availible from Autozone,etc),install in the sparkplug hole,remove all plugs,open the carb wide open and secure it open,remove the coil wire from the dist cap and ground it. Spin the engine over while watching the gauge,it should in 4 or 5 stokes be at it max reading. Do the other cylinders and compare the readings.

Re: 1972 Duster 340 #8 cylinder won't fire [Re: goldmember] #337212
06/03/09 06:16 PM
06/03/09 06:16 PM
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renton, Washington
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before you do that swap the 7 and 8 plug wire at the plugs and see if that helps dan

Re: 1972 Duster 340 #8 cylinder won't fire [Re: reno340] #337213
06/03/09 07:31 PM
06/03/09 07:31 PM
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Millinocket, Maine
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If you have power brakes, make sure the booster hose is attached to the intake nipple or make sure there is no leak there (7 and 8 intake runner is at this point.) BTDT.

Re: 1972 Duster 340 #8 cylinder won't fire [Re: JonC] #337214
06/03/09 08:08 PM
06/03/09 08:08 PM
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Maryland
reno340 Offline OP
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I do have spark. I wonder how bad this is gonna get? The guy that sold me the car in 1991 said he rebuilt the engine doing a ring and bearing type of rebuild. I hope that rules out anything in the short block.


"There are only three real sports, Mountain climbing, Bull Fighting and Auto Racing. The rest are just games"
- Earnest Hemmingway


If you can't run with the big dogs, stay on the porch!!

https://www.youtube.com/watch?v=_xQJtN1_6DU
Re: 1972 Duster 340 #8 cylinder won't fire [Re: reno340] #337215
06/03/09 10:42 PM
06/03/09 10:42 PM
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Grand Prairie,Texas
stumpy Offline
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Sounds to me like you need to spend a few buck to have a mechanic check it out. It will be cheaper in the long run.

Re: 1972 Duster 340 #8 cylinder won't fire [Re: stumpy] #337216
06/03/09 11:48 PM
06/03/09 11:48 PM
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Lincoln Nebraska
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as said do a compression test


live every 24 hour block of time like it's your last day on earth
Re: 1972 Duster 340 #8 cylinder won't fire [Re: RapidRobert] #337217
06/04/09 12:24 AM
06/04/09 12:24 AM
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the boonies
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Quote:

as said do a compression test


and get rid of those platimum plugs. they are for longevity not performance

Re: 1972 Duster 340 #8 cylinder won't fire [Re: aarcuda] #337218
08/27/09 08:10 PM
08/27/09 08:10 PM
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Maryland
reno340 Offline OP
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Sorry it took a long time to get around this. I did a compression test on the passenger cylinder head and got these results. #2- 110lbs, #4- 125lbs, #6- 130lbs, #8- 120lbs. #8's plug is perfectly clean other than gas. (remember I had tried switching wires, plugs, cap, rotor....) What gives?





"There are only three real sports, Mountain climbing, Bull Fighting and Auto Racing. The rest are just games"
- Earnest Hemmingway


If you can't run with the big dogs, stay on the porch!!

https://www.youtube.com/watch?v=_xQJtN1_6DU
Re: 1972 Duster 340 #8 cylinder won't fire [Re: reno340] #337219
08/27/09 08:34 PM
08/27/09 08:34 PM
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Upper Midwest
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You got compression, you got fuel, you got spark. It should fire. Put in a new plug, one that isn't gas fouled. recheck your spark plug wire orientation, make sjure that the right wire is going to the correct plug following the firing order. The firing order is 1-8-4-3-6-5-7-2 clock wise around the cap.

Re: 1972 Duster 340 #8 cylinder won't fire [Re: MoparforLife] #337220
08/27/09 08:45 PM
08/27/09 08:45 PM
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renton, Washington
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5 and 7 are probably crossed double ck dan

Re: 1972 Duster 340 #8 cylinder won't fire [Re: MoparforLife] #337221
08/27/09 09:04 PM
08/27/09 09:04 PM
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Posts: 386
Maryland
reno340 Offline OP
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Quote:

You got compression, you got fuel, you got spark. It should fire. Put in a new plug, one that isn't gas fouled. recheck your spark plug wire orientation, make sure that the right wire is going to the correct plug following the firing order. The firing order is 1-8-4-3-6-5-7-2 clock wise around the cap.


I kind of already did that:
Quote:

Help! I have a 1972 Plymouth Duster 340 w/ factory electronic ignition. My # 8 plug won't fire. I replaced it w/ Bosch Platinum plugs, New cap and rotor and a new wire set. I took that plug and switched it w/ #2's plug and #8 cylinder still does not fire


I poorly explained I changed the plugs and #8 would not fire so I switched it w/ # 2's plug and it still did not fire but #2 cylinder fired fine. I am not above doing it again. I have double checked the firing order too. I can recheck it again though since I still haven't found the problem.


"There are only three real sports, Mountain climbing, Bull Fighting and Auto Racing. The rest are just games"
- Earnest Hemmingway


If you can't run with the big dogs, stay on the porch!!

https://www.youtube.com/watch?v=_xQJtN1_6DU
Re: 1972 Duster 340 #8 cylinder won't fire [Re: ph23vo] #337222
08/27/09 09:16 PM
08/27/09 09:16 PM
Joined: Mar 2005
Posts: 386
Maryland
reno340 Offline OP
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Quote:

5 and 7 are probably crossed double ck dan


Will that effect #8?


"There are only three real sports, Mountain climbing, Bull Fighting and Auto Racing. The rest are just games"
- Earnest Hemmingway


If you can't run with the big dogs, stay on the porch!!

https://www.youtube.com/watch?v=_xQJtN1_6DU
Re: 1972 Duster 340 #8 cylinder won't fire [Re: reno340] #337223
08/27/09 09:18 PM
08/27/09 09:18 PM
Joined: Jan 2003
Posts: 14,471
renton, Washington
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if you are using fat white electrode platimum plugs dont! if they have the tiny pin like tip they should be ok dan

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