gap on #8 plug gap closed at high RPM! - Northern California Ford Owners

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»	Northern California Ford Owners » Automotive » Tech Talk » gap on #8 plug gap closed at high RPM!

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Topic: gap on #8 plug gap closed at high RPM!

Elapid
GOROBGO
Member # 50

posted

am i screwed?
1996 supercharged cobra
freeway races with ws6 firehawk and z28 camaro w/ heads. it started missing after i hit the rev limiter (i think stock one). i pulled the plugs, and #8 is squished.

is it possible that detonation caused this?
or is impact with the piston more likely?

thanks!

--------------------
98 Cobra
83 Notch rolling chassis - fs

Posts: 1797 | From: Grass Valley, CA USA | Registered: Jul 2000 | :

PunkINa5.SLOW
¯
Member # 10

posted

just stick a new plug in it!

--------------------
OUTTA THA DRAMA

R.I.P. MIKE STARKEY MY BABY BROTHER
12/8/77-5/17/03

Posts: 2495 | From: MTZ | Registered: Sep 2000 | :

notsue
¯
Member # 557

posted

is it just me or does that thing look wet?

Posts: 616 | From: Fort Riley | Registered: Nov 2001 | :

John91coupe
CAFords OG
Member # 18

posted

Looks like you have several issues with that cylinder. One is that it looks oil soaked which means you've got a problem with the rings or valve guides. It also looks like you've got some water spots on it, don't need to tell you what that means. The fact that the electrode bent over like that would indicate either it hit something or it was messed up when you put it in. If it was somehow bent going in that could also explain the oil soaking and wet look which means that the electrode was shorted out and the plug not firing.

I'd do a compression check before anything else. If it checks out OK then put a new plug in and check it after a day or two of running.

--------------------
D-2R ProCharged R302 331
1.410 60 ft.
5.784 @ 122.92 1/8
8.953 @ 155.08
MM&FF Feature June 2003

Posts: 1361 | From: Grass Valley, CA | Registered: Sep 2000 | :

PunkINa5.SLOW
¯
Member # 10

posted

You do realize I was just playing around when I said to stick another plug in it.

Are you sure that was the correct spark plug to begin with?

--------------------
OUTTA THA DRAMA

R.I.P. MIKE STARKEY MY BABY BROTHER
12/8/77-5/17/03

Posts: 2495 | From: MTZ | Registered: Sep 2000 | :

Elapid
GOROBGO
Member # 50

posted

i have heard that the rods can stretch...i used a flashlight to inspect the piston, I don't see any obvious damage of any sort. I put in a new plug and it runs fine. I was over at the dss website pricing shortblocks with forged internals...very tempting! If the motor goes south, i guess that's the way to go. then i could add spray too!

--------------------
98 Cobra
83 Notch rolling chassis - fs

Posts: 1797 | From: Grass Valley, CA USA | Registered: Jul 2000 | :

Elapid
GOROBGO
Member # 50

posted

oh yeah.
the plug is so wet because i drove for 30 miles with it like that.

--------------------
98 Cobra
83 Notch rolling chassis - fs

Posts: 1797 | From: Grass Valley, CA USA | Registered: Jul 2000 | :

99gt-UJSTLST
¯
Member # 584

posted

quote:
Originally posted by rob:
am i screwed?
1996 supercharged cobra
freeway races with ws6 firehawk and z28 camaro w/ heads. it started missing after i hit the rev limiter (i think stock one). i pulled the plugs, and #8 is squished.
is it possible that detonation caused this?
or is impact with the piston more likely?
thanks!

well if it would of been detonation you would have no electrode it would of burned off due to the heat also is it soaked in oil if so I agree looks like bent valves or a blown rings
well hoping it was just soaked in gas

later

--------------------
SOUTH BAY STANGS
MINOR BOLT ON'S

www.southbaystangs.com

Posts: 2558 | From: SAN JOSE CA | Registered: Nov 2001 | :

Milesblown03
¯
Member # 27

posted

Unless the motor is coming apart, i dont think theres any way the piston contacted the plug. The plug is pretty much all the way at the top of the chamber. I dont know what could cause the bent plug though. Ive seen a few instances on a few different cars where the electrode would bend. Could never figure it out. Usually only happened to one plug too... i would do a compression/leakdown test just to be sure theres no motor damage

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99 honda 996 superhawk...
03 cobra:422rwhp,399rwtq (before pulley)
New best,12.07@119.9(!!)mph on nittos (cant drive to save my life!)

Posts: 1002 | From: Hayward, CA | Registered: Jun 2000 | :

Elapid
GOROBGO
Member # 50

posted

I'm going to baby it for awhile.
if the piston is cracked, it won't hurt much when it burns through if i don't rev the shit out of it.

--------------------
98 Cobra
83 Notch rolling chassis - fs

Posts: 1797 | From: Grass Valley, CA USA | Registered: Jul 2000 | :

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