Pond 510 Running Rich

[My427stang]

I would not go changing things until you're sure the O2 sensor is giving a correct reading, as Jay said. At that level of richness (given a correct reading), the engine should not be running good. Are your exhaust pipes showing heavy black soot? Are the plugs showing black soot? If the exhaust is not showing heavy soot inside the tailpipes, then I'd think you're getting faulty info. The black smoke out the exhaust upon hard acceleration should be obvious looking in the rear mirror if it really is that rich. Have someone follow you and watch if you can't watch in the mirror.

Like Barry said, those carbs tend to be on the rich side out of the box, but with such a big cubic inch displacement they may not be as bad as is normally found. And yes, I'd leave the secondary carb the same as the primary. Changing the back one will lead to issues under hard throttle once things are dialed in.

Good advice, regardless of what they may or may not be, with a potentially bad sensor you could be chasing windmills.  8:1 is flooding, it would be pretty obvious

I would change one thing at a time, and have the carbs matched, both in tuning parts and throttle positions at idle. 

[BigBlueOvalFan]

Thanks for all the responses, I truly appreciate the brainstorm as it really helps. 

I tried to load some pics of the plugs but my file sizes are too large.  I'm at 3MB and the limit is 194kb, no idea how to rectify that, wish I could.   They are NGK-R BKR6E plugs. I'm not much in the mood to remove all the plugs as it's in a '67 Mustang with the tall finned Shelby valve covers that chew up your knuckles.  It also has the export brace which needs to come off as well to make things a bit easier.  I know it's running rich, I just don't know how rich as it burns your eyes when standing behind it after a couple raps of the throttle.  No black smoke and the exhaust tips don't show any black residue but then again it has only been run for a total of about 15 minutes after sitting for 6 years (the last time being fired when it was on the dyno when it was built).

On another note, apparently I was looking at the PV incorrectly and after speaking to Holley, they confirmed it is a 6.5.  I'm still going to drop it to a 5.5 and maybe drop a jet size to 62's and start with my readings since it's been the consensus that these carbs come rich and Barry stated he's run them with as low as a 57 jet. 

I'll check with innovate regarding the O2 being able to handle the 110 leaded for extended periods of time. I also will check with them about how to download the info from the 15 minutes and if it recorded anything or if I have to start over. 

More to come and thanks.

[cjshaker]

Burning eyes indicates a lean mixture, not rich. No soot in the exhaust and no black smoke would support that also. You could potentially be making a big mistake by leaning it out more. A BIG mistake. If you're running a leaded fuel, that could be the cause of your O2 readings. I don't know how well O2 sensors tolerate leaded fuel, maybe others can chime in there, but leaning it out with no other indications of being rich than a questionable sensor reading is NOT the way to go.

[BigBlueOvalFan]

Burning eyes indicates a lean mixture, not rich. No soot in the exhaust and no black smoke would support that also. You could potentially be making a big mistake by leaning it out more. A BIG mistake. If you're running a leaded fuel, that could be the cause of your O2 readings. I don't know how well O2 sensors tolerate leaded fuel, maybe others can chime in there, but leaning it out with no other indications of being rich than a questionable sensor reading is NOT the way to go.

I always thought that the rich mixture was indicated by the burning eyes sensation.  I guess as they say, you learn something new everyday.  The new game plan is to put it all back together exactly as it was and speak to Innovate about the O2 and it's abilities.  Aren't O2 sensors used by racers and on dyno's all the time to read A/F ? 

[thatdarncat]

Racers will often just use the O2 sensors in a "test" only mode - make a pass, log the data and remove the sensor after.

[cjshaker]

I'm no expert, but I do know that lead will build up on everything which can negatively affect many sensors.

A rich fuel mixture has a pungent smell, but it's the NOX in a lean mixture that burns the eyes. But most importantly, the lack of black soot or smoke indicates that it is not overly rich. Your plugs and tailpipe will not lie to you or give you a false reading.

[BigBlueOvalFan]

I'm no expert, but I do know that lead will build up on everything which can negatively affect many sensors.

A rich fuel mixture has a pungent smell, but it's the NOX in a lean mixture that burns the eyes. But most importantly, the lack of black soot or smoke indicates that it is not overly rich. Your plugs and tailpipe will not lie to you or give you a false reading.

Thanks for the help Doug.  I just spoke to Innovate and they stated that running the O2 in a constant unleaded fuel environment will shorten it's lifespan but running rich will do more harm than the unleaded fuel.  In speaking to them, I came up with a game plan; 

I'm gong to install their vacuum/rpm gauge and daisy chain it to the A/F gauge.  They have a recorder unit that will attach to these gauges and provide up to 17 minutes of recorded data on a SD card.  The software will display A/F, RPM and Vacuum throughout the test period you choose and you can overlay this data from one run to the next.  So my plan is to capture the data and tune the vehicle and then remove the O2 until I make a change.  The hardest part will be to find a test track or stretch of hwy or abandoned street that is safe.  In SoCal, that's a big order.  I'll post my results afterwards and will keep the carbs the same with exception to adding some new squirters (same size .031) with nozzles and the hollow nozzle screw to allow for more flow to the squirter. 

I truly wish I could post a pic of the plug I pulled out of #4.  The porcelain is black/dark grey w/lighter grey spotting and the top of the ground electrode has tan/brown spots almost like rust.

[Barry_R]

Small carb(s) on a large engine will actually tend to roll rich - they give an overly strong signal to the booster and pull a lot of liquid unless you tune to compensate with bleeds or booster design changes.  That plug sure sounds like a fat one by your description.  The accelerator pump tuning is a completely different issue to deal with.  The power valve sounds a lot closer to what I would have expected.

[BigBlueOvalFan]

Small carb(s) on a large engine will actually tend to roll rich - they give an overly strong signal to the booster and pull a lot of liquid unless you tune to compensate with bleeds or booster design changes.  That plug sure sounds like a fat one by your description.  The accelerator pump tuning is a completely different issue to deal with.  The power valve sounds a lot closer to what I would have expected.

Thanks Barry for the comments.  I read a little about the pump as well and figure I have quite a bit to learn about tuning the carbs.  I think it's best I start with a good reading from the gauges and produce a log much like a chassis dyno would. I just hoped that enough of these FE's have been built in this configuration, that it would be a good idea to hear what has worked prior but it seems as though each situation is different. 

I also pulled the #1 plug and it was the same, black porcelain with a light brown spots on the very tip of the ground electrode.  I'll see if I can find a lower resolution camera and post a pic.

Thanks, Jim

[barrys65cyclone]

Jim
  Just a thought have you verified that all float levels re correct ?

[BigBlueOvalFan]

Jim
  Just a thought have you verified that all float levels re correct ?

Barry,

It's odd that you ask that as I was just looking at that today and noticed that the "dry" float level were at below parallel to the bowl which reduces the amount of fuel in the bowl.  I'm tempted to set them dry at parallel to the bowl before putting them back on the car but wonder if they were set correctly "wet" by the engine builder when the dynoed the engine.  I have a funny feeling that the builder just installed them as purchased and didn't spend anytime dialing it (which wasn't necessarily their job anyhow as I didn't pay for dyon tuning). I guess there's only one way to find out.

Would a low float setting produce a lean situation ?

[barrys65cyclone]

could very well be but i would verify float settings are correct before any carb alterations.

[jayb]

The float settings will depend to some extent on fuel pressure, so they are best set on the car, with the engine running and the carb getting its normal fuel pressure.  Unless the floats are really, really low, they aren't likely to cause a lean condition.

[machoneman]

2X to what Jay said. Fuel pressure becomes important too as a street engine s/b at about 6 to 6.5 psi max. 7 is for race stuff and even then it's edgy. While running near 7 lowering the floats a tad does offer minor, and I do mean minor, leaning. At 6, your in the ballpark if the floats are set correctly and then tuning can begin.

Holley btw has a series of vids on various aspects of carb tuning that may be helpful....unless your an old hand at this! 

https://www.holley.com/blog/carburetor_installation_and_tuning/1/

[barrys65cyclone]

The float settings will depend to some extent on fuel pressure, so they are best set on the car, with the engine running and the carb getting its normal fuel pressure.  Unless the floats are really, really low, they aren't likely to cause a lean condition.

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