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Spark Plug #1739559 01/26/15 10:26 PM 01/26/15 10:26 PM
Joined: Jan 2005 Posts: 1,772 Keymar, MD DusterKid OP top fuel
DusterKid OP top fuel Joined: Jan 2005 Posts: 1,772 Keymar, MD	I have a mild 360 that I race that is approx 10:1, edelbrock heads and a run a mixture of 1 gal 110 + 3 gal 93 pump gas. 3 or 4 years ago I was putting new plug wires and changed the plugs and notice I had 2 or 3 (I can't remember) plugs that the ground electrode was broke at the bend part. I figured the plugs were old since I didn't remember changing them recently. I just tore the motor down for a freshen up this past month and I had 3 more that were broke. Cylinder 1, 6, 8. I know these plugs are less than 2 years old, so now I"m questioning if I'm running the right plug. The plugs are autolite 3924's. So I guess my question is first off what is causing this? and obviously what do I need to do to fix the issue to prevent this from happening again?

Re: Spark Plug [Re: DusterKid] #1739560 01/27/15 12:19 PM 01/27/15 12:19 PM
Joined: Jul 2004 Posts: 19,317 State of confusion T Thumperdart I Live Here
Thumperdart I Live Here T Joined: Jul 2004 Posts: 19,317 State of confusion	So r u saying they really broke or are they wore out? If they actually broke from contact then that`s a whole nother deal....... 72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....

Re: Spark Plug [Re: DusterKid] #1739561 01/27/15 12:29 PM 01/27/15 12:29 PM
Joined: Jun 2003 Posts: 52,972 Romeo MI MR_P_BODY Master
MR_P_BODY Master Joined: Jun 2003 Posts: 52,972 Romeo MI	If they were burnt off thats one thing.. most times when they break off they break at the weld point .. tell us if they are burnt off... lets see a pic.. also if they were hit by the piston they would be bent down EDIT I run that same plug in my street/strip 416 with 10.4 compression.. also make sure you didnt put in the AR3924... thats the short ground strap for racing Last edited by MR_P_BODY; 01/27/15 12:35 PM.

Re: Spark Plug [Re: MR_P_BODY] #1739562 01/27/15 09:00 PM 01/27/15 09:00 PM
Joined: Jan 2005 Posts: 1,772 Keymar, MD DusterKid OP top fuel
DusterKid OP top fuel Joined: Jan 2005 Posts: 1,772 Keymar, MD	I didn't see where they made contact with the piston to bend or brake. The 3 plugs picture were list this, the other 5 were normal. Since all the plugs had the same about of runs on them, if they were worn, wouldn't all of the plugs be about the same or no? Here are a few pictures. [image][/image] [image][/image]

Re: Spark Plug [Re: DusterKid] #1739563 01/27/15 11:57 PM 01/27/15 11:57 PM
Joined: Jul 2004 Posts: 19,317 State of confusion T Thumperdart I Live Here
Thumperdart I Live Here T Joined: Jul 2004 Posts: 19,317 State of confusion	Quote: I didn't see where they made contact with the piston to bend or brake. The 3 plugs picture were list this, the other 5 were normal. Since all the plugs had the same about of runs on them, if they were worn, wouldn't all of the plugs be about the same or no? Here are a few pictures. [image][/image] [image][/image] Looks like someone cut their own ground straps to me....... 72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....

Re: Spark Plug [Re: Thumperdart] #1739564 01/28/15 01:08 AM 01/28/15 01:08 AM
Joined: Jun 2003 Posts: 9,225 Charleston S sixpackgut Drag Week Mod Champion
sixpackgut Drag Week Mod Champion S Joined: Jun 2003 Posts: 9,225 Charleston	I use to run that plug when they were made in USA. When they started to be made in china or wherever, i will say around 2005, I quit buying them and started buying the AR plugs. I have never seen that happen and I have seen pistons hit plugs but it usually just bends the strap Gen 3 power 6.22@110, 9.85@135 Follow @g3hemiswap on instagram performance only racing, CRT, ultimate converter, superior design concepts, ThumperCarbs

Re: Spark Plug [Re: Thumperdart] #1739565 01/28/15 12:47 PM 01/28/15 12:47 PM
Joined: Oct 2003 Posts: 7,506 Az Crizila master
Crizila master Joined: Oct 2003 Posts: 7,506 Az	Quote: Quote: I didn't see where they made contact with the piston to bend or brake. The 3 plugs picture were list this, the other 5 were normal. Since all the plugs had the same about of runs on them, if they were worn, wouldn't all of the plugs be about the same or no? Here are a few pictures. [image][/image] [image][/image] Looks like someone cut their own ground straps to me....... Man manipulated. Not even all the same. Strange. Fastest 300

Re: Spark Plug [Re: DusterKid] #1739566 01/28/15 01:03 PM 01/28/15 01:03 PM
Joined: Jun 2003 Posts: 52,972 Romeo MI MR_P_BODY Master
MR_P_BODY Master Joined: Jun 2003 Posts: 52,972 Romeo MI	I see weld splatter on the one washer... but those ground straps look like the material is messed up.. they look like carbonized.. the grain structure looks really goofy.. I would say that it burnt off.. was it the same cyls that did it a second time

Re: Spark Plug [Re: MR_P_BODY] #1739567 01/28/15 01:21 PM 01/28/15 01:21 PM
Joined: Feb 2005 Posts: 20,173 PA. pittsburghracer "Little"John
pittsburghracer "Little"John Joined: Feb 2005 Posts: 20,173 PA.	Kinda off topic but why are you mixing race gas with that compression. Did you ever do a cranking compression test? 1970 Duster Edelbrock headed 408 5.984@112.52 422 Indy headed small block 5.982@112.56 mph 9.42@138.27 Livin and lovin life one day at a time

Re: Spark Plug [Re: pittsburghracer] #1739568 01/28/15 02:13 PM 01/28/15 02:13 PM
Joined: Jan 2005 Posts: 1,772 Keymar, MD DusterKid OP top fuel
DusterKid OP top fuel Joined: Jan 2005 Posts: 1,772 Keymar, MD	Def not done by man, the other 5 plugs look normal. I wish I could remember which cylinders it was last time to see if it is a trend with the same cylinder, but I don't remember. I mix race gas with pump gas because I was having issues with the fuel boiling when the weather would get hot ever since they started to put ethanol in fuel. Ignition is an MSD 6AL box, running MSD street fire 8 mm plug wires.

Re: Spark Plug [Re: DusterKid] #1739569 01/28/15 03:05 PM 01/28/15 03:05 PM
Joined: Jan 2003 Posts: 5,894 Florida Locomotion master
Locomotion master Joined: Jan 2003 Posts: 5,894 Florida	I've had a few do that, but I believe that I may have weakened the straps by bending them around so the tip of the ground strap was centered over the electrode or even a bit further back. My ground strap were almost verticle, then made a sharper turn towards the electrode. I also tend to run lean, so it could be a combination of what caused it. If it was "contact", the electrodes would likely have been bent down more.

Re: Spark Plug [Re: DusterKid] #1739570 01/28/15 03:15 PM 01/28/15 03:15 PM
Joined: Oct 2003 Posts: 7,506 Az Crizila master
Crizila master Joined: Oct 2003 Posts: 7,506 Az	Quote: Def not done by man, the other 5 plugs look normal. I wish I could remember which cylinders it was last time to see if it is a trend with the same cylinder, but I don't remember. I mix race gas with pump gas because I was having issues with the fuel boiling when the weather would get hot ever since they started to put ethanol in fuel. Ignition is an MSD 6AL box, running MSD street fire 8 mm plug wires. Well, if they were "blown off", you would think you would see marks on the pistons / combustion chamber areas?? Did they all just roll out the exhaust without hitting anything? I guess that's possible? From the slant of the electrodes, looks like they were firing, even with those gigantic gaps - and the edges of the ground straps are still very crisp. Something is missing ( info ) from somewhere. Fastest 300

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