I've spent hours reading articles on the web and this site and I still haven't run across a good example that is similar to my plugs. Usually, the photos that are shown are of extreme cases and aren't representative of what we would typically see in one of our cars. The best photos and the most straightforward description that I have seen are on Pat Kelly's web site.

My combo is a 331 with 062 vortec heads and a 272/286 lunati cam with 54 degrees of overlap and 454/480 lift. I'm running autolite platinum 605 plugs that were spec'ed for a 1998 chevy truck, which is what the vortecs are designed for. The carb is a Holley 600 VS with 65 jets up front and a metering plate in the back with a 69 jet equivalent orifice. My timing is 36 degrees total. My power valve is a 6.5, is not blown, and my vacuum at idle in gear is 12-13 inches.

My plugs show a soot ring around the base thread of the plug that you can flick off with your thumbnail and the strap is clean to within a 1/16" of where it attaches to the base ring of the plug. The porcelin is white and the tip is clean like the strap. I think it is still running rich as evident with the base ring black soot. I didn't have a jet below 65 so I used a trick that pat did in one of his post which stated that you could use a strand of wire and run it through the jet holes. The wire is secure and can't come out.

Anyway, I cleaned the plugs, took it for a drive and pulled the plugs as soon as i got back. The soot ring is still there and the strap is clean to the same place as before. Should I keep jetting down, i.e. put some more wires in there to restict the flow? Also, with the strap clean but not glazed, should i be concerned about pre-ignition.

Any help would be greatly appreciated as I don't know what I'm doing with the jetting and potential detonation.

As far as I know when you take a plug reading you should do a hard run, shut down and pull the plug. If you are doing a run then driving home you are getting a false reading. Some others should chime in soon.

reading plugs is almost impossible with todays gasoline. they just don't color like they did with leaded fuel. and it's gonna take a fair amount of driving to color them and you need to use new plugs each time. so on those notes it's best to get a wide band sensor and tune it that way or on a dyno. if either of those options are not available you can do it by driving but forget the plug reading go with seat of the pants feel. lean it down on the primary side till you get a lean surge at part throttle and then increase jet size by two, and thats only good for that temperture air you did the testing at. and stop putting wires in the jets they aren't that expensive.

The soot can be from a few things; The type of fuel you're running, the overlap of the cam, or too rich on the jets. The jets sound reasonable, so I would try a different brand or lower octane of fuel.
You are also running a little bit too much total timing for the vortecs, back it down to 32-34.
As was mentioned, the article on Pat's web site are only for full throttle, fresh plugs, with no idleing.
Also if you are primarily driving on the street, a little rich is good, cause it bumps the torque up a little in the mid range.
I would try the fuel first.

soot ring on the base thread? That isn't even in the cylinder so that's more a function of how dirty your engine block is than how the mixture and timing are.

The photos on the website referenced above are WRONG it points at a base ring as being the threads but it is the base of the porcelain where the sun don't shine.

Like said above, put a new set of plugs in and make a full pull, shut off clean and swap the plugs before idling/driving. Then post a picture here of the ground strap and a picture with a flash down into the base of the porcelain (easier said than done) and people will be able to help.

I ordered a few new sets of jets today and I'll pick up a new set of plugs and give it a try. The wire was just for a trial to see if it improved or not. I tried the pictures when I posted the original post and they didn't turn out, very blurry.

66 283 - The soot ring I was talking about was not at the base of the threads but the flat ring at the end of the plug where the strap attaches. They do stick into the combustion chamber about 1/32". The reason I think this indicates a rich condition is because everything in the combustion chamber, headers and even all the way back through the exhaust system is dark black. Others i have seen are usually a medium grey to light grey.

Clyde

How is carb adjusted? Have you adjusted floats, idle mix and to highest vacuum?! Agree that timing may be a little high at 36!

Blazerbob,

The floats are correct as per everything I've read about adjusting them. Gas just starts to come out when you lean on the fender. Whenever i try to adjust the idle mix with the vacuum gauge, the vacuum changes very little but I can cause the car to shut down if I turn the idle screws in and also kill it by backing them out. My vacuum gauge needle cycles continuously, due to the cam overlap, so its hard to tell if it changes much as the rpm increases or drops.

Clyde

Do you have a vacuum advance ??

Try a run without the platinums they are causing lots of grief with many different motors.

My vacuum advance is limitted to 10-11 degrees. Any suggestions on the plugs for vortec heads? Any thoughts on what the problems are with the platinum plugs?

Clyde