chymos

Ok....in setting timing, I didn't put any whiteout or anything in the timing mark to make it more visible, and think I accidentally advanced it a bit too far. Result: dead/blown up plug. Definite solid miss on the same cylinder.

What should I be most concerned with as far as other damage? The valves?

How likely is it I'll have to pull the heads? I'd really rather not do that until I can replace them with something decent. They're just a set of 426s

Basically, what are the chances the engine would survive for 6 months or so, and what would I have to do to prevent further damage from the remains of the plug?

I'm going to pull the plugs and find which it is tomorrow.....

89RsPower!

pull em out.. if anything is broken off any of em i would try fishing around in the cylinder with a magnetic pick up tool to remove any metallic debris and follow it up with a compression test to determine if there was any damage

Vader

How long did it run that way?

What plugs are you using?

Were you able to hear audible knock?

RB83L69

Change the plugs. Move on.

You don't ruin a spark plug by advancing the timing. The probability of a fouled plug causing any kind of motor damage is about as close to zero as it can be. Plugs don't generally fall apart.

chymos

it ran for about 15 minutes tops with an audible knock, though it sounded more like some sort of detonation than knock.

the plugs are Bosch Platinum 4's......

If it wasn't a defective/damaged plug, what could it have been?

Once it started missing on that cylinder, the sound stopped, but there's a blatant and regular miss....kind of like bapbapbapbapbapbapbappausebapbapbap.

I'm currently running open Hedman shorties until I get everything working and can drive it to the exhaust shop....no CC.....HEI coil-in-cap dist., 426 heads, not sure what cam, Performer intake, and a Holley 600cfm 4160 with open element air filter. also an electric Holley carb fuel pump (the red one), full '87 accessories....

chymos

I'm afraid that I wasn't able to get to it today......had other things that needed taken care of....

With luck, I'll get to it sometime this weekend. Or not, given that X2 is out tomorrow and saturday's my b-day......among many other things happening this weekend.....

chymos

Ok....it took me a while, but I finally got to looking at it....checked all the plugs....a couple were fouled, but after wiping them off, they looked fine.....couldn't get it started, though, due to a dead battery....and the car I was using to jump it off sprung a radiator leak

any ideas what it could be? when I cranked it over, it sounded like one of the cylinders either wasn't firing or the valves weren't closing or weren't opening or something......time to pull valve covers again?

TomP

I was running with way-over-advanced timing a long time ago... found that out when I replaced my first fuel pump, and the car still wouldn't run. (Yes the 1st pump was bad! ) So after verifying that yes, I now had enough fuel pressure, I started looking at other things. Pulled the #1 plug and it had no center electrode or insulator or ANYTHING. Found out the timing was so far advanced that it was off the scale.

Ran a compression test a few years later, every cyl was around 140-160 PSI, but the #1 cyl was 125 PSI. I guess those pieces of spark plug had their fun I'm pretty sure I saved the plug, if it ever emerges from the basement, I'll put a pic up. Heck, that was before I found thirdgen.org ...