wandering/stumbling idle..FIXED..but possible uh oh

[acannell]

so..did several WOT launches at 16.5 PSI

brought car back to garage.everything idling okay, seems fine. Vacuum 21mmHg. Nothing unusual seen.

Next day, did a bunch of stuff to install a pressure sensor on the exhaust header.

Started the car up..idles like crap. Uh oh..did I crack a piston? Vacuum still around 20 to 21mmhg..usually when I crack a piston it goes down to 18 mmhg.

Idle wanders around 1000rpm maybe +/- 100rpm..can here various pops every now and then in exhaust. Engine seems to be missing/vibrating.

Figured I must have popped a vac line off or bumped something.

Went through the usual laundry list:

-checked timing: OKAY
-checked fault codes: NONE
-checked vac lines by disconnecting and doing the ol stick-to-tounge vac test...some of them were actually leaking quite a bit and had cracks. Fixed them. Heater hose vac source line was cracked in half. Taped off. Disconnected charcoal canister system entirely and plugged TB ports.
-tested fuel reg vac line..clean as a whistle, holds vac
-pinched off PCV vac line which is clearly leaky and cracked
-checked distributor and rotor..kinda eroded but no big deal. metal vanes solidly mounted.
-put timing light on each plug wire, all seemed the same

So none of that fixed it.

Next I tried:

-taking all 4 spark plugs out..hmm #1 plug had a little puddle of I think oil in its pocket...yikes. Replaced #1 with another used plug I had laying around.
-Otherwise plugs all looked normal. None felt loose. I always torque them with a torque wrench so I have no reason to believe they would be loosen anyway.
-wiggled fuel injector plugs just in case I didnt seat them very well

Started it up..ROCK SOLID IDLE. As good as it gets basically.

VIDEO CLICK HERE (http://vid.me/NbsM)

Heres a video of the fixed idle. Sorry I dont have a video of the bad idle.

So while I was typing this I forgot if the #1 plug looked weird in anyway. I went out to the garage to grab it. Hmm looks normal. I turned it over and heard a "clink"....

so how did that happen? I've never seen this before. Does that mean there was heavy detonation? Engine seems to be running great.

This is an autolite 63.

http://i242.photobucket.com/albums/ff197/acannell/20141121_105453_zpshk5mgpw4.jpg (http://s242.photobucket.com/user/acannell/media/20141121_105453_zpshk5mgpw4.jpg.html)

http://i242.photobucket.com/albums/ff197/acannell/20141121_105538_zpsu0hdwtjl.jpg (http://s242.photobucket.com/user/acannell/media/20141121_105538_zpsu0hdwtjl.jpg.html)

[shackwrrr]

Yep common detonation damage. Keep an eye of tailpipe smoke and oil consumption the next few days to make sure pistons are ok.

[acannell]

Yep common detonation damage. Keep an eye of tailpipe smoke and oil consumption the next few days to make sure pistons are ok.

you know it does seem that way..but what makes me suspicious is that I dont usually have Autolite 63's installed. I usually have the RN9YC's. And I've had epic detonation before and cracked 4 pistons on separate occasions, including an excursion beyond 30 psi (no wastegate control), and never seen a broken insulator. Perhaps the autolite 63 is more fragile and maybe I damaged it somehow by banging it or dropping it?

[acannell]

okay I went out to the garage and took an autolite 63 and tapped the insulator a few times..it broke in exactly the same way. I'm going to call this mechanical/accidental damage. I'm off to autobone to get RN9YC's. I'll test an old RN9YC the same way and see what happens.

[acannell]

i did an RN9YC "tap test" and it brok etoo...

so imma just chalk this up to me weakening the insulator by mishandling, then it breaking after a thermal cycle in the engine

case closed

[ShelGame]

so..did several WOT launches at 16.5 PSI

brought car back to garage.everything idling okay, seems fine. Vacuum 21mmHg. Nothing unusual seen.

Next day, did a bunch of stuff to install a pressure sensor on the exhaust header.

Started the car up..idles like crap. Uh oh..did I crack a piston? Vacuum still around 20 to 21mmhg..usually when I crack a piston it goes down to 18 mmhg.

Idle wanders around 1000rpm maybe +/- 100rpm..can here various pops every now and then in exhaust. Engine seems to be missing/vibrating.

Figured I must have popped a vac line off or bumped something.

Went through the usual laundry list:

-checked timing: OKAY
-checked fault codes: NONE
-checked vac lines by disconnecting and doing the ol stick-to-tounge vac test...some of them were actually leaking quite a bit and had cracks. Fixed them. Heater hose vac source line was cracked in half. Taped off. Disconnected charcoal canister system entirely and plugged TB ports.
-tested fuel reg vac line..clean as a whistle, holds vac
-pinched off PCV vac line which is clearly leaky and cracked
-checked distributor and rotor..kinda eroded but no big deal. metal vanes solidly mounted.
-put timing light on each plug wire, all seemed the same

So none of that fixed it.

Next I tried:

-taking all 4 spark plugs out..hmm #1 plug had a little puddle of I think oil in its pocket...yikes. Replaced #1 with another used plug I had laying around.
-Otherwise plugs all looked normal. None felt loose. I always torque them with a torque wrench so I have no reason to believe they would be loosen anyway.
-wiggled fuel injector plugs just in case I didnt seat them very well

Started it up..ROCK SOLID IDLE. As good as it gets basically.

VIDEO CLICK HERE (http://vid.me/NbsM)

Heres a video of the fixed idle. Sorry I dont have a video of the bad idle.

So while I was typing this I forgot if the #1 plug looked weird in anyway. I went out to the garage to grab it. Hmm looks normal. I turned it over and heard a "clink"....

so how did that happen? I've never seen this before. Does that mean there was heavy detonation? Engine seems to be running great.

This is an autolite 63.

http://i242.photobucket.com/albums/ff197/acannell/20141121_105453_zpshk5mgpw4.jpg (http://s242.photobucket.com/user/acannell/media/20141121_105453_zpshk5mgpw4.jpg.html)

http://i242.photobucket.com/albums/ff197/acannell/20141121_105538_zpsu0hdwtjl.jpg (http://s242.photobucket.com/user/acannell/media/20141121_105538_zpsu0hdwtjl.jpg.html)

You're lucky. When mine did that, the ceramic fell out and bounced around the cylinder for a little bit. There's now little indents all over. Oddly, that cylinder still has good compression 6 years later.

[GLHNSLHT2]

Try Autolite AR51's instead :)

[acannell]

Try Autolite AR51's instead :)

have you noticed a difference with those? i dont think ive had any problems with the RN9YC's

[GLHNSLHT2]

Yep, A friend and I took out his brand new RN's and swapped in my used AR51's and the car idled smoother and revved up quicker. They have some things going for them. Bigger insulator and ground electrode for better heat dissipation and the electrode is ground back for a better flame front which allows you to run less timing slightly and have a more complete burn for more power and better MPG and emissions. It'd probably be even better if I indexed them.

[Ondonti]

If that happens without wacking it on a table then they were too hot. I did that to quite a few and caused the same mechanical damage Shelgame mentioned. Made me go back to a stock block because I didn't feel like repairing the damage. Motor ran fine but when inspected I saw it and I wanted to go another direction. That is when I ran stock 3.0 heat range plugs when troubleshooting and forgot to change them out for a little friendly racing. Car had a hard time at the top of each gear, eventually not pulling at all. Misfired constantly on the way home. Pulled plugs and while most were broke and hung down, 1-2 had fallen apart. That can cause damage to valves and seats as well.

[boboli]

Post edited!
The picture I posted was not the one that appeared in the post. I have never seen the posted pic in my life ( though I have visited the real site, not the inferred one).
The picture that did appear offended me, as it had nothing to do with anything in this post.
No idea how that happened
Sorry

[crusty shadow]

Yep, A friend and I took out his brand new RN's and swapped in my used AR51's and the car idled smoother and revved up quicker. They have some things going for them. Bigger insulator and ground electrode for better heat dissipation and the electrode is ground back for a better flame front which allows you to run less timing slightly and have a more complete burn for more power and better MPG and emissions. It'd probably be even better if I indexed them.

Actually the Champion RN and RN6 electrodes are thicker than the autolite AR51. I bought a set of AR51's a while back because of how you were talking them up, made them sound like a miracle plug plus they were on clearance so I figured why not.
the electrode on the AR51 measures out at .081 in while the champion RN6 electrode measures out at .092 in . the grund electrode is thicker on the champion plug as well
the quality of the insulator on the autolite plug is substandard at best- looking around where the insulator goes back into the plug body there are all kinds of jagged burrs and splinters of ceramic material where it looks like the insulator was too large to fit in the metal plug body and it was just rammed in there anyway. no such issues with the champion plug- insulator is perfect on every one, no splinters or shavings of ceramic material , just looks like a high quality plug. The only real advantage the AR has over the RN is that the AR plug has a side gapped ground electrode- that is what is making it seem like such a good plug, but anyone with a hand file and 20 minutes of spare time can side gap the RN plug and get the same results with a much higher quality plug.