Running Champion F11YC, but looks like the plug may be a step too hot, and jetting too rich?

Just installed dual exhaust, only pulled #5 plug only so far, just want to get an idea. Stock Autolite 2100 1.02" venturi size, probably with stock 46 jets. Timing set about 12 degrees BTDC, stock cam, pulls 19" vacuum at idle, etc.

 

Looking at the ground electrode it looks like they are a little too hot. I don't see anything that would indicate too rich, what makes you think that?

 

Well, nothing other than my new found wisdom - I read it on the internet! So, it must be true. The jetting is probably OK, but I don't see how stock plugs could run hot in a stock engine.

The plug reading experts claim that the porcelain color is more or less misleading to look at for jetting, but instead look at that first thread ring. This color should be more a light soot when jetted correctly. The ground strap electrode color is used for determining heat range.

 

I was making my assessment of the color on your ground strap just as shown in your posted picture above. I'm not sure of the heat ranges of Champion plugs, I only use Autolite or Motorcraft in my Fords. I use Autolite 45 in my Y block. You are always safer to be a little rich then too lean..

 

I was actually looking at those wideband exhaust analyzers. I should have pulled the trigger and set it up before installing dual exhaust. Many people say they were amazed at how far off the optimum air-fuel ratio their engine was, even though it ran OK.

I ordered a set of Motorcraft plugs to replace these. Champions don't have a very good reputation. Autolite 45s seem to be the go to plug for Y blocks.

Here is some of the info I am working from:

http://www.dragstuff.com/techarticle...ead-plugs.html

 

Those are good guide lines and basically what I use, but I'm just a shade tree mechanic. I do run the engine hard, kill the ignition and coast down the street and into the garage before a plug check. At idle I don't care what the mixture is as long as I get a good idle.
One thing I have noticed is the color difference since leaded gas went away and now ethonal added, Just like the tips of my exhaust pipes use to be nice tan color in the past and with todays fuel they are always black.. Thats with California crap blended fuel, other states may be different.

 

Well, lookie want Santa brung me... An O2 Wideband!

Stay tuned...

Sent from a pay phone

 

Thats too high tech for me LOL

 

Nah, they are pretty easy to use! If I can figure it out, anybody can. It will be interesting to see how far off the beam I was in my tuning. Also picked up several feet of vacuum hose to determine cruise vacuum. The stock (green) 7.5" power valve should be correct, but tuners suggest choosing a number about 2" below the minimum cruise vacuum found at cruise.

Still wondering about excessive fuel pump pressure, had to bend the float arm down quite a lot to get the float height such that, the fuel level height in the bowl stays in spec at idle.

There's really no definite up and down with the float at idle (careful!) - like a toilet tank float might work say - it just sort of spews constantly from the needle seat. I thought a carburetor at idle would work on the fuel in the bowl for a minute or so. It does maintain the fuel level correctly though spot on. I'm told that carburetor floats don't work like a toilet tank float, but then why do they have the huge adjustment range? Had to take up virtually all of that, the float now has maybe an 1/8" of an inch clearance or swing from low to high/closed.

 

Even a basic (Narrow band?) O2 sensor is a valuable tool. Makes tuning so much easier. Some of the fancy ones have data acquisition software to go along, but that is not so useful unless other sensors are in place to compliment it. That allows you to get the data on a computer and allows you to focus on the road.

 

It's very interesting to learn carburetor tuning, even though EFI made them obsolete. Just tired of guessing on A/F ratios, wondering if I'm going to burn a valve or something.

Ran pig rich for a long time, compression seems fine, it burns no oil tho wonder if the cylinders are glazed over from all that carbon.

I'm assuming that the acceleration circuit in a stock OEM carb - power valve - is on the rich side of things, and that's good. But an Autolite doesn't have a metering plate like Holleys do. There is quite a bit of stuff folks can do to dial in the PVCRs with a Holley.

Is there any mods that can be done with the 2100 power valve circuit if required? Maybe snaking in some fine bread-tie wire to lean it out if indicated? No way am I drilling any holes in that thing.

It might be fun after the 2100 is dialed in to try and tune the old Holley 500 2bbl with the wideband as well and/or could set it up for high altitude use, and be able to make a quick swapout when visiting our Very Large Square States. I had planned on selling it, but haven't got around to it.

Sent from a pay phone

 

Got everything hooked up tho haven't taken it for a drive yet. Idle was pretty lean at 16 to 1. Just a slight turn of the mixture screws makes a big change to the A/F ratio.

 

Used the wideband to try and jet this thing for better economy on the highway. Had to hog out the power valve channel restrictors a few thou to keep the wide open throttle from going too lean, this is important, can't just jet down and call it good.

But made a pretty good progress. When I was running the Holley 500 cfm mpg was about 9 or 10. Swapped in an Autolite and managed 12.

This week after wideband tuning fuel mileage was either 15.8 or 16.4 mpg, fully loaded depending on the actual distance travelled. The odometer said 380 miles, but the maps feature on my "smart" phone sez it was 393, not sure who to believe. Speeds were 60 to 70, lots of hills and definitely did not drive with an eye towards economy. Everybody drives like a maniac these days.

Couple observations, Corn gas is bad stuff, I knew that already but it really shows up when things are tuned close to the edge. Wind makes a big difference too, but everybody knows that too. But these old rigs can get reasonable mileage if tuned right.