alexcoreas

iTrader: (1)

Can someone explain why this happened and point me in the right direction please, plugs have no more than 5k miles on them. Motor is a LS2 , bald eagle blower cam and supporting mods from TSP. Thank you in advance . This is the #7 spark plug

B52bombardier1

Something hit it, probably a valve. Did a valve float a little during a high RPM excursion with the tachometer?

Rick

G Atsma

A valve can't hit a spark plug.

old motorhead

iTrader: (10)

Detonation will close the gap.

alexcoreas

iTrader: (1)

no, nothing like that. It sounded like a zip tie on a driveshaft until I let off the gas and took it easy on the drive home which took about 4 min.

old motorhead

iTrader: (10)

How much oil is it using? Oil in the combustion chamber decreases octane. Low octane leads to detonation. Detonation does that kind of **** to spark plugs.

alexcoreas

iTrader: (1)

hard to tell since I change the oil every 3 months regardless of miles give or take 1500miles . I drive this car on weekends only. Oil is always clean, I always put 6qts and that’s what I pull out every time . I checked the gap on plug 5 and 3 and they’re at .070. If that information helps any

alexcoreas

iTrader: (1)

#5

Austin Phil

Possibly something rattling around inside that cylinder. Maybe a throttle plate screw, piece of mass air flow sensor, top land of piston broke off. Something rattling around in there will make the sound of a zip tie against the drive shaft as you describe. Use a borescope attached to your smart phone or shine a light with mirror if needed, in the spark plug hole and look for spots in the top of the piston and a piece of debris. In your picture, there's a piece of the porcelain missing from the center electrode. Did the porcelain break before or after the negative electrode got bent? The piece of porcelain could be rattling around in there. Don't run the engine until you find the issue.

grinder11

iTrader: (1)

I agree about the possible detonation. It could've taken a piece of porcelain out, and that could've caused it. However, and this isnt totally on topic, but why in Hell are you running a .070" plug gap??? That is way too big......

grinder11

iTrader: (1)

Also, if a borescope reveals that piece is still on top of the piston, you can tape up a piece of tubing, like fuel hose, etc., to a shop vac. Then insert thru the plug hole until you get it out. It doesn't even have to suck it thru the hose, just needs to hold it on the end of the hose while you remove the hose and discard it. Almost looks like the plug was dropped on install. I once got a new set of 8 plugs, and one of them came just like that, with the ground strap slammed against the ignitor tip. Since then, I always check the gap when installing new plugs, pre-gapped plugs be damned. Then I know for sure.......

alexcoreas

iTrader: (1)

I’ll order a borescope as we speak and take a look inside.

this was my first time swapping a motor, and I think I was in over my head, I bought a used ls2, put a cam, lifters , pushrods , spring , oil pump ect and changed the head gaskets I think I was in over my head that I didn’t check the plug gap because I thought it would have been to spec since they were new. Figured I’d just throw them in and go. Definitely my fault for not checking.

Im going to do this once the borescope comes in. I honestly didn’t check plug gap when I installed them.

I want you all to know I really appreciate all the feed back and help

grinder11

iTrader: (1)

One thing I always do is check the gap. My sparkplug that had the ground strap slammed against the electrode in my new set of 8 NGK plugs had the cardboard sleeve in place to prevent this from happening. HOWEVER-The sleeve, and the other 7 sleeves on the other 7 plugs were all perfect. No sign of damage. So, I had proof that something happened to the plug before it was packaged and shipped. Maybe dropped, or a couple imbeciles on the production line tossing them at each other? Who knows. This was at least 25 years ago, and I've always checked my gaps ever since. FWIW.....

alexcoreas

iTrader: (1)

Not checking might have cost me more money..
here are the pictures from inside the bore .

Old Buzzard

Someone mentioned MAF....
Well, that wire stuck in the piston may have been the retainer snap from the MAF.
In any case it has to come apart.

C409

iTrader: (1)

We shouldn't be able to see the top of the top ring ... the upper ring land is missing from a substantial portion of the top of that piston .

grinder11

iTrader: (1)

Yup, time for a teardown when the piston or MAF set the spark plug gap! Sucks.......

LilJayV10

iTrader: (39)

It can if you try hard enough.

G Atsma

True dat.... LOL

jayyyw

Was it tuned after you did the swap and installed the cam?