A/F ratio off?

[DartVadar]

Plugs are still good, but clean them because the carbon can cause them to loose spark (shorts thru carbon). I applaud you for installing a wideband O2 sensor. With A/F in the 10's, you probably have black smoke from the exhaust. You verified that the choke plate is full open when it runs rich. The main other thing to cause "too rich" is if the fuel bowl level is too high, or overflowing into the throat. That is commonly caused by debris in the needle seat, which is easy to remove and check in most carburetors. The float can also sink, but your carb is fairly new. One other thought is if you have the "heated air inlet" as in ~1973+ cars, if the diverter door in the air cleaner sticks in the "hot air" position, it can run rich. That happened to one friend in a Ford Escort soon after those things came out. On a long trip, they started getting 10 mpg and found a stuck door was the problem.

Ill give the plugs a clean, and I am sure I did have some smoke coming out, it was running like crap! The choke was good and the carb looked nice and clean inside. And I have an aftermarket air cleaner so its just the filter element sitting on top. The fuel was the culprit though!

 

[AJ/FormS]

Fresh gas is very nearly clear. Then it goes yellow, orange and reddish. If you ever pour a teaspoon of reddish gas on the concrete floor, and then light it on fire, you will see it working really hard to stay lit. Whereas the clear stuff will flash so fast you cant light it with a lighter and not get burned. In an unsealed container, it (E-10) will go from clear to dark in a week or so. If sealed and stored away from sun, it will last maybe a month. Maybe. If stabilized it will last all winter, even unsealed. Thats been my test results.
--Popping in the exhaust is usually an unburned charge (as in missfire) ignited by a following still-burning exhaust charge,or fresh air (as from an air leak) entering the pipe.
-Now why it would read rich on the WB; Im gonna guess insufficient available oxygen to properly oxidize the stale fuel.
-Btw, as you may know a cold engine requires lots more fuel. And the colder it is, the lots morer. And with stale fuel the VOCs are gone so needs even more fuel.As you have discovered, the WB doesnt know everything. As long as the engine is close to running properly it can be an excellent tool. When not running properly, theres no substitute for experience.In the beginning,I let the engine tell me what it wants. Then use the WB to sneak up on the optimums.
-Just my 2 cents

 

[DartVadar]

Fresh gas is very nearly clear. Then it goes yellow, orange and reddish. If you ever pour a teaspoon of reddish gas on the concrete floor, and then light it on fire, you will see it working really hard to stay lit. Whereas the clear stuff will flash so fast you cant light it with a lighter and not get burned. In an unsealed container, it (E-10) will go from clear to dark in a week or so. If sealed and stored away from sun, it will last maybe a month. Maybe. If stabilized it will last all winter, even unsealed. Thats been my test results.
--Popping in the exhaust is usually an unburned charge (as in missfire) ignited by a following still-burning exhaust charge,or fresh air (as from an air leak) entering the pipe.
-Now why it would read rich on the WB; Im gonna guess insufficient available oxygen to properly oxidize the stale fuel.
-Btw, as you may know a cold engine requires lots more fuel. And the colder it is, the lots morer. And with stale fuel the VOCs are gone so needs even more fuel.As you have discovered, the WB doesnt know everything. As long as the engine is close to running properly it can be an excellent tool. When not running properly, theres no substitute for experience.In the beginning,I let the engine tell me what it wants. Then use the WB to sneak up on the optimums.
-Just my 2 cents

The gas looked very yellow, as dark as apple juice but more yellow. And I cleaned my air cleaner (It was quite dirty actually, was probably restricting some air and not helping the rich condition). I took a plug out again to see what they looked like after driving around for a bit with the new gas, and they were starting to get clean again, I am taking them all out to clean them fully now.

And I think for one thing my car just hates even somewhat cold weather, I will start it in the morning from my garage (heat isn't turned on yet) and it takes a while to warm up and stays quite rich for a long time, but when its nice and warm that same day in the afternoon it starts up perfectly and doesn't run nearly as rich.

 

[BillGrissom]

The old mechanical chokes were too slow to open, causing too rich for too long on cold mornings. Electric chokes were intended to fix that, with an electric heater "anticipating" the heat-up of the exhaust manifold. You could try adjusting the rich-lean setting on your e-choke, setting it as lean as possible while still starting OK. Also, insure the heating element isn't broken. It should measure <100 ohm to ground.

 

[DartVadar]

Okay so to update on everything, the car runs just like it always has now. But I am starting to think that I just have a rich issue still. I am thinking that I need to jet and tune the carb as I am probably leaving some power on the table.

Once warmed up the car runs really good, warmed up idling it runs 12.8-13.2 AFR, and light cruising its at 11.6-12. WOT it stays around 12.5, so the WOT seems to be good. Its just the light throttle cruising that seems much too rich. The carb is a holley 650 with vacuum secondaries.

I am out of time to really drive it this year but I am just wanting to figure out what I should do to get it right.

 

[mderoy340]

A holley is still on the idle circuit at light cruise up to around 2200-2400 rpm. Cruise around there and you'll be able to see the AFR change and transition into the primary jet. Light cruise at 12 is way rich. Start with going down 2 jet sizes on the primary. My car runs best at 14.7 light cruise but every motor is different. Also if your fuel has 10% alcohol 14.2 AFR is best at cruise and 12.1 WOT since the alcohol is not as efficient as 100% real gas.
You should really have almost no color on the plugs if the AFR is right.

 

[DartVadar]

A holley is still on the idle circuit at light cruise up to around 2200-2400 rpm. Cruise around there and you'll be able to see the AFR change and transition into the primary jet. Light cruise at 12 is way rich. Start with going down 2 jet sizes on the primary. My car runs best at 14.7 light cruise but every motor is different. Also if your fuel has 10% alcohol 14.2 AFR is best at cruise and 12.1 WOT since the alcohol is not as efficient as 100% real gas.
You should really have almost no color on the plugs if the AFR is right.

I have 2.76 gears currently (changing to 3.91s soon) so just driving around town easy It usually never gets past 2k rpm, so it is probably still in the idle circuit.

So adjust the idle mixture and jet the carb down to get it close to 14.2 should make it run alot better? But it seems like my WOT mixture is pretty good however. The damn thing also loves fuel, I kinda have a heavy foot though

 

[nm9stheham]

Just so you don't have any misconceptoins: Being in/out of the idle cirucit does not depend on RPM per se but vacuum near the idle and transtion slots, which depends on a combination of RPM and how far the throttle is open. The idles drop out as throttle opens, and then you are in the transitions for a bit more of the throttle opening process. Once throttle opening is so far, the vacuum near the idle and transition drops off and the aristream quits sucking fuel/air mixture from those 2 sources. The mains come in as flow exceeds a certain amount.

Your WOT mixture is determined by the power valve in addition to the mains; so the mains are not setting WOT throttle mixture by themselves. The mains:
- set AFR along with the power valve at WOT
- set AFR at moderate cruise when the power valve is off
- and also feed into the idle wells where fuel and air is mixed for the "idle fule/air mixture" and effect 2 things.

From the idle well, there are 2 paths to feed that fuel/air mix ("idle fuel/air mixture"):
- The idle mixture screw sets the amount of that fuel/air mix in the idle well that is fed into the engine at idle which sets the idle AFR.
- That same fuel/air mix in the idle wells also feeds into the transition slots when you are at very light cruise and sets AFR for light cruise. So since the mains feed fuel into the idle wells, then changing the main jets effect the light cruise/off-idle AFR via changing the idle well's fuel/air mix.

Also, with a low rear gear, you will be more likely into the power valve at light-to-moderate throttle. The engine revs less quickly with a tall (lower numerical) gear, and the low vacuum last longer and tends to let you get into the power valve easier. Observing a vacuum guage will show this. So a lower power valve number may be appropriate for higher AFR but not to where it causes a big stumble in the transition to WOT.

Suggestion: It might be really helpfulto you to read up on Holley carb operation some more; there are some good explanations out there with good illustrations of things like the idle well.

 

[Mattax]

It seems like when it warms up at idle it runs at around 12.7-13.3, and leans out a little bit as you get on the gas, I haven't really charted it too much.

This is how it should work (once its warmed up enough the choke isn't needed). At some point, as load increases to somewhere around 70 to 80% throttle, a richer mix is needed. That's when the power valve needs to let in more fuel to get a WOT mix in the 12.3- 12.9 AFR range.

The exact numbers to target varies. Your target is best performance and efficiency, the numbers just let you keep track of what is going on. A lumpy cam will need richer mix than a stock engine at idle and off idle to deal with the exhaust reversion.

My own experience has been that main jets will not effect light throttle (cruising) until somewhere in the 55-65 mph range.

Urich and Fisher's Holley Carburetors and Manifolds or even the little 4150/60 book are good introductions to the basic principles of each circuit. There's also some pamphlets from Chrysler on carburation including Holleys on-line. Go to www.imperialclub.org and look through the Master tech series to find these. Even so, I recommend finding a copy of Urich's books to get the principles

 

[MopaR&D]

Sounds like you need to jet down (also lean out the idle) and enlarge the Power Valve Restrictor Channels to keep your WOT mixture right. Kinda sucks because I doubt your PVRCs are screw-in with that carb and you'll have to drill them out to enlarge them.