moparman

Since it was so nice out today, I decided to change plugs and wires on on my '96 Formula. Things were going as well as could be expected for a LT1, until I got to #7. It came out normally. Tried to put the new plug in, and it won't start. After several attempts I looked at the old plug, and the threads on it had an aluminum color. There's no metal on the old plug, just the color. Are the threads in the hole stripped? Does the head have to come off, or is there a way to repair on the car? Spark plug thread chaser? How does the chaser start in the hole if the plug won't?

planemech2

You can get a thread cleaner/tap for spark plug holes. Bad thing is chips can get into the cylinder. If you can, take a mirror and light and look at the hole to see any damage. If none, use a SMALL amount of anti sieze compound on the plug, then try to put it back in by hand. Take your time and be careful not to tighten the plug too much.

shoebox

I had to remove the exhaust manifold to even be able to see if there was some kind of thread problem when I had an issue like that. That was a long time ago on my first plug change and it was the problematic #2 cylinder. I was able to use a chaser to clean it up (gob it up with some heavy grease to catch any shavings and crank it with the plug out to purge any others). The plug was fine, but I put a thread repair insert in it when I had the heads off later. There is hardly enough room to do a thread insert correctly with the head on the car.

If you goof it up with the chaser, then your pretty much screwed. It has to go in straight and true and match up to the old thread pattern. NAPA sells a tool that chases the threads from the inside out (if there is enough room to use it). Normally, the inside threads are still good, so that particular tool can sometimes work.

94zgreenmachine

Anti seize should be used anytime and all the time on your plugs when going into the cylinder heads. Aluminum and steel have a nasty reaction to each other and will corrode when left unprotected.

moparman

I always use anti-seize. I was able to get the tip of my little finger into a portion of the hole, and I could feel the threads. Could it be that only the first thread or two on the outer end are stripped?

Out of all the plugs I've changed over the years, I've never had this happen. First time for everything, I guess.

shoebox

Yes, it could be. It does not take much damage to keep a plug from going in. It might have been damage from a previous plug change.

moparman

Would a chaser still have to go all the way in, or just clean up the outer end?

moparman

Well, I looked at the hole with an inspection mirror and flashlight. The threads appear to be OK, unless there is not supposed to be a small countersink on the outside of the hole.

Had some visitors today, so didn't really get a chance to mess with it, other than look at it.

94zgreenmachine

I have a problem with 6 and 8. Under the car, starter removed and layin on my back. It could be that you don't have the right angle on them. Are you doing this with the stock manifolds or headers?

This could be especially troublesome if you are leaning WAY over, one hand on the intake, the other fumbling with the plug trying to spin it. Lets hope that's all the trouble is......

moparman

Stock manifolds. Car is on jack stands, and I'm on a creeper, working underneath.

moparman

Good news. After getting over the frustation, I didn't mess with it again until yesterday. Rolled back under the car with the flashlight and mirror. Threads appeared OK. Tried putting the plug in again. Still couldn't get it started. Tried several times before rolling out from under. Got a beer, sat down and began thinking aout it. It dawned on me that perhaps if I rolled under it feet first, it would give my right hand a more natural position to handle the plug, rather than the twisted way I was trying before. I was right. It only took a couple of tries, and I was able to get the plug in. Whew.

shoebox

Good deal. When you are working in the blind (bolt or spark plug, whatever) and trying to thread it in, try turning it counter-clockwise until the threads come square to the hole, then try spinning it in.

94zgreenmachine

So, how much swearing did you do before you got it in? These cars almost always require you to twist into a god awful angle to do something, like you are Gumby or something.

moparman

I did do some cussing. You're right about having to be a contortionist to really be able to work on these things. I did see a guy change plugs and wires on a stock LTI from the top, except for putting them on the opti. They called him Spider because he could bend and twist in all kinds of funny diredtions. I wish I knew how to contact him. I'd pay him to do some of this stuff.

94zgreenmachine

What may help as well, is an old trick. Put the plug into a piece of fuel line and use it to start them. The nice thing is that you can manipulate the plug to go any direction you want it to. This is especially nice with the angle plug heads. I even have long tubes and I STILL can't see everything on every plug. Glad you got it worked out. Now that I think about it, maybe IT was the beer..........