Pulled the plugs out of my 451 for the first time in about 3 years. How do things look to you guys. I run 4 jet sizes bigger in my 800 holley. All plugs are pretty well identical.

As you know they need replaced or beaded. I use one of those mini plug cleaners with shop air & fine black abrasive (forget what type it(the abrasive) is) & it works great & makes em look like new. The ground strap tells the heat range & the flat on the threaded end tells the AF ratio rather than the insulator as commonly thought but I might be wrong on that. Google it & there are some very comprehensive sites w pics for this which'll tide you over till you spring for the innovate LM1. You ain't running too hot nor carbon or oil fouled so I'd say you're in the ballpark. EDIT found it: www.wallaceracing.com & scroll down to the "plug reading" article. pics & very informative

I would lean it down two jet sizes and put in a new set of plugs and drive it for 20 to 40 miles at part throttle(no WOT dashes ) and see what the new plugs look like then I think it is on the rich side so leaning it down some should make the car more responsive and move the color change location up towards the middle of the ground strap, right where it ought to be

So..........................
What I've done now just to mess stuff up is put on an HP main body and change the plugs out one heat range cooler. I also went up from 70/78 jets (dual powervalves) to 74/80. Raised fuel pressure from 6-1/4 to 7. No timing changes. This is what the plugs look like after 5 or six days driving to work.

Maybe a little better shot?

everyday driving (choke/accel pump) skews readings. For main metering I would go out on the highway till it's warm then pull over & replace one plug (on the hottest cyl) with a new plug & unhook the accel pump rod then ease back on the highway & drive for 10 miles or so staying out of the power system then shut the ign off/put it in neutral/foot off of the gas & coast to the side of the road & pull that plug (take a pic) & see what you see

There are a lot of cars that run great at WOT but would foul up in traffic. Chasing perfect A/F mix in all conditions can be tough with a holley especially without a wideband afr meter and vacuum meter in the car.

Often with a strong motor the cruise will be fed from the T-slot and the main jets won't even come on yet. Tuning this circuit is done first with the Idle Feed Restriction (IFR) which is not a screw in jet in most holley metering blocks, then fine tuned with the air bleeds.

If it looks that clean and you are happy with drivability I'd leave it alone. My considerations for being happy with the tune are easy starting, crisp acceleration, optimized WOT, and decently lean cruise.

If you have a regular highway trip or long back roads there is a good chance you could have a fat off-idle cruise and the higher rpm highway cruise gets into the main jet circuit and cleans up the plugs. That's how mine used to be which was fine at the time. Then I moved close to work and my plugs started fouling weekly from 35mph stop n go every day. The car would get sluggish and start harder. I had to lean out my IFRs in my metering blocks.

Tuning a carb is always a compromise- you have to decide what your goals are and go for that. If you don't load up in traffic, idle clean, and run your best number WOT, and manage to run a set of plugs for 3 years (!!) I'd say you got it licked!

my plugs were grey/white and i thought maybe i was too lean.I installed a wideband a/f gauge and my cruise and idle readings were 12's.
i went 8% leaner to get mid thirteen readings which is still a bit rich.
very hard to read plugs with today's fuels

Cab, the car feels great. Starts better than my 04 Ram.
No choke of course and idles by the time I back out of the garage. Throttle response is fantastic as far as I'm concerned. 35pri and 31sec squirters. From just off idle it'll tach out instantly in first and second gear with ET Radials. Cruise is great , hot start is, well, hot start, ha ha.
I have NO driveability concerns, just that this is the whitest I've ever seen my plugs. With the new main body and significantly larger low/high speed air bleeds I was questioning things.