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Re: Attn engine builders need help troubleshooting 383
[Re: repad]
#747765
07/13/10 11:11 PM
07/13/10 11:11 PM
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Joined: Jan 2003
Posts: 667
CA
66Dodge
super gas
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super gas
Joined: Jan 2003
Posts: 667
CA
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Quote:
I began by pulling one wire at a time. Starting with #1, when I got to #3 there was no change the way the engine ran. Then I removed the plug and it looks like new, never been fired.
Check under the dist. cap. Maybe contact for #3 is bad ?
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Re: Attn engine builders need help troubleshooting 383
[Re: GregCon]
#747769
07/14/10 12:10 AM
07/14/10 12:10 AM
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Joined: May 2004
Posts: 679
N.E Indiana
repad
OP
super street
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OP
super street
Joined: May 2004
Posts: 679
N.E Indiana
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Quote:
You could buy one of those Lisle spark plug lights to see if you are getting spark at the plug. It goes between the plug and the plug wire and has a window that lets you see the spark.
I checked the plug removed from the cylinder and an additional wire run from the plug to ground and have spark.
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Re: Attn engine builders need help troubleshooting 383
[Re: kzinge1]
#747770
07/14/10 12:12 AM
07/14/10 12:12 AM
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Joined: May 2004
Posts: 679
N.E Indiana
repad
OP
super street
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OP
super street
Joined: May 2004
Posts: 679
N.E Indiana
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Quote:
Might be a bad ignition box. I had a brand new MSD box that wouldn't fire #1 and #4.
Sorry, no ignition box, running on points.
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Re: Attn engine builders need help troubleshooting 383
[Re: repad]
#747772
07/14/10 12:32 AM
07/14/10 12:32 AM
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Joined: Jan 2003
Posts: 667
CA
66Dodge
super gas
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super gas
Joined: Jan 2003
Posts: 667
CA
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Quote:
Any advice on how to verify if the #3 contact on the cap is at fault?
Just suggesting a general visual inspection to see if it looks any different from the other 7 contacts.
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Re: 383man
[Re: 383man]
#747774
07/14/10 12:59 AM
07/14/10 12:59 AM
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Joined: May 2004
Posts: 679
N.E Indiana
repad
OP
super street
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OP
super street
Joined: May 2004
Posts: 679
N.E Indiana
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Quote:
You said the plug looked like new ?? If it was not firing it would be wet with fuel. Sounds like a vacum leak effecting that intake runner causing a very lean condition in that cyl. Ron
I concur, the plug is not wet with fuel which leads me to now believe that the backfire may have caused a leak to develope in the valley pan around the intake runner for #3. I had not considered this because there is no visual evidence of a leak but thanks to your and the first responders insight, that is where I will concentrate my efforts tomorrow and post an update.
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Re: 383man
[Re: GregCon]
#747775
07/14/10 01:06 AM
07/14/10 01:06 AM
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Joined: May 2004
Posts: 679
N.E Indiana
repad
OP
super street
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OP
super street
Joined: May 2004
Posts: 679
N.E Indiana
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Quote:
A leakdown test won't tell you anything regarding this problem. If you have 160lbs on a regular gauge, that's all you need to know.
You could have a dud plug that only fires at atmospheric pressure but I doubt it.
How about this - have you verified the spark is occurring at the time of compression? My next guess is you have two wires swapped so #3 is sparking on the exhaust stroke somewhere and the other cylinder happens to be close enough that it fires even if it is not exactly right.
I'd pull the plug, put my finger over the hole, and crank the motor while watching the spark - does it fire as your finger is shoved off the hole?
The engine is not real smart...if it has compression, fuel, and spark all more or less at the right time it has no choice but to fire.
The possibility of crossed wires was one of my initial thoughts. I did check the wire routing and they are all correct.
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