Opinions wanted on spark plug diagnosis.

[CAChevy]

Hey gang. I've pulled my spark plugs attempting to diagnosis a rough running engine at all rpms. The motor is a new 350/260 crate from GM that I put a cam/rockers in and changed out the head gaskets.

There's been a few scary moments with this motor. I did the break in..2-3k rpm for 20-25 min with RP break-in oil. And all was fine upon shut down. The next day started it up to tune the ccc Quadrajet, (unsuccessfully so), and after running it at idle-2500 rpm and after it warmed up, closed loop...it looked like it was running on oil...lots of oil smoke and oil was physically running out of the small leaks I have on the passenger side efe onto the garage floor. Ya, I freaked out and shut it down.

Dropped the oil and there were lots of very fine brass colored bits in the oil drop from the filter. Smaller than grains of sand but I could see it. Not so much in the drop from the pan. Pulled apart the oil filter and was surprised not to see very much of it at all in the media. I did see the normal bits of silver grey magnetic which I've seen before on new builds. Other than that and the smell of fuel..it was fine.

Put new oil back in it with another go around of RP break in for giggles. After start up and once it got warm...burned a little oil then cleared up and after 5-6 short tuning sessions in the garage trying to get this miserable Quadrajet dwell correct, I haven seen it burn any oil at all.

I also found 4 burnt plug wires where the boot insulators didn't do their job vs the headers. I've got to get a new set of wires and reroute under the headers and see if that works better.

Anyways...attached are the plugs that have been in since the build started. I think some look a little hot, some a little cold. I don't really know what to think. I'd almost bet the dog a few of those plug wires were shorting out on the headers cause part of my rough idle though.

Sorry this post is so chopping and grammatically challenged..I'm using my iphone to post because the picture I uploaded is on the phone.

[Mr.Chevy4x4]

1, 2, and 5 look pretty good. 6, 7, and 8 look a little rich but not terrible. 4 doesn't appear to have been firing at all, and 3 looks like it quit firing recently. Which wires were burnt? Looks like your carburetor tuning is pretty close. I would correct the misfires, run it for a while, and then recheck the plugs. What plugs are you running?

Mike

[CAChevy]

The wires on 3, 4, 5, and 6 were burnt pretty bad but I can't confirm that they were bad enough to arc to ground. I suppose at that voltage it doesn't take much.

The plugs in the picture are ACDelco R45TS. I plan on putting a new set of shorty Accel 8199's back in it to try and gain some clearance from the headers. Waiting on UPS to bring the new wires.

Regarding the incident where the truck mysteriously started then quit burning oil. I bought this truck on the cheap because the original 305 blew up and seized. Is it possible that there was residual oil in the evap canister due to that original engines demise? Is is also possible that when the computer gave the new engine the signal to purge the evap canister the oil could have been sucked into the intake? Enough to puddle on the garage floor?

[Mr.Chevy4x4]

I build a lot of 4-wheeler engines for people. More often than not the unit will smoke for a while with the new engine due to all of the oil in the exhaust from the engine using oil before the rebuild. It usually takes 10-20 minutes to burn it all out.