FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: BigBlueOvalFan on September 28, 2015, 08:15:18 PM
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Hello Everyone,
I'm running a Pond 510 w/Stage II Keith Craft heads, a tunnel wedge w/2 Holly 600's (4160's). My wide band O2 is giving me a reading of 8:1 under small load w/110 octane fuel. I pulled the front carb which is my primary (using progressive linkage) and my jets are 64 which seem to be on the small side. Before I make a bunch of mistakes and have to tear this thing apart 20 times, I figured you guys might give me some direction. I haven't looked at the power valve yet to check the number but will do so next. If more info is needed, please let me know.
I haven't checked my secondary (back) carb yet but would assume it is matched to the front.
Any help would be great.
Thanks, Jim
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Small update;
The rear carb is also setup with 64 primary jets and both carbs have 8.5 power valves which is most likely my rich problem.
I'm going to swap out the power valves for 4.5 as I have about 10lbs vacuum at idle.
My next question would be; do the 64 jets in both carbs sound correct for the new power valve and should the carbs be staggered with different jets and power valves with a progressive linkage setup ?
Any help would be appreciated.
Thanks, Jim
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Little steps first.
Power valves sound like a good place to start since you have ones that seem high for the application.
Can you monitor vacuum while running under that load & speed? Cell phone video camera, cheap vacuum guage, duct tape, and a running commentary can help as a poor man's datalogger so you can gather information and drive at the same time...
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Agree with Barry.
The jets are already a bit lean, most 850s usually run a 66, so I like the PV plan
As far as your choice on power valves though, I wouldn't go 4.5, that's likely too far the other way. My guess would be 5.5 or 6.5 but to be sure, I would recreate the 8:1 and see what you are pulling for vacuum at that load with a gauge hanging in the car and delay the PV a bit.
Typically, when I see a guy go 1/2 of idle vacuum or so, he has to compensate by jetting up, then it goes fat later, although that is a safe technique, it isn't right.
Also, realize that one of those could be bad, look for wet in the chamber behind it or test with vacuum. Having it THAT rich, is generally more than just PV timing
Other things like float level or plugged or bunged up air bleeds can add to it.
Finally, if recently apart, metering surfaces on the body can warp and cross channel, but to me it sounds at this point like you may have a PV issue
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I think I'd be suspicious of the O2 sensor reading. 8:1 is at the very bottom of the scale. How does it read under full throttle acceleration, is that number reasonable? While you are seeing 8:1 on the O2 sensor, are you getting black smoke out of the exhaust? If you were really that rich, the engine ought to be stumbling, and you should be seeing a bunch of black smoke.
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Great observation by Jay - I missed it.
My dyno O2 systems run a fat to lean calibration loop on startup - both sensor readings go to full rich and it's indeed 8:1, then the sweep to full lean at 16:1 before they fall into a normal reading range. At a steady 8:1 you are more likely to be seeing bad data than anything really useful.
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Little steps first.
Power valves sound like a good place to start since you have ones that seem high for the application.
Can you monitor vacuum while running under that load & speed? Cell phone video camera, cheap vacuum guage, duct tape, and a running commentary can help as a poor man's datalogger so you can gather information and drive at the same time...
Barry,
I have a mechanical vacuum gauge and Innovate digital WB O2 that can download info in the car. This was the first time out after a 7 year build and I was more interested in listening for rattles, etc. The engine was dynoed by the builder and when I inquired as to how rich it was running, he stated that it probably fattened up because of the air cleaner. I have my suspicions that they didn't really spend anytime dialing it in after seeing the 8.5 PV's and 64 jets. I think they just ran the carbs that I purchased.
I'm going to try pulling the data off the O2 today and see what I get.
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Agree with Barry.
The jets are already a bit lean, most 850s usually run a 66, so I like the PV plan
As far as your choice on power valves though, I wouldn't go 4.5, that's likely too far the other way. My guess would be 5.5 or 6.5 but to be sure, I would recreate the 8:1 and see what you are pulling for vacuum at that load with a gauge hanging in the car and delay the PV a bit.
Typically, when I see a guy go 1/2 of idle vacuum or so, he has to compensate by jetting up, then it goes fat later, although that is a safe technique, it isn't right.
Also, realize that one of those could be bad, look for wet in the chamber behind it or test with vacuum. Having it THAT rich, is generally more than just PV timing
Other things like float level or plugged or bunged up air bleeds can add to it.
Finally, if recently apart, metering surfaces on the body can warp and cross channel, but to me it sounds at this point like you may have a PV issue
Thanks for the response,
I'm going to change the PV from 4.5 to the 5.5 per you suggestion and buy a couple 6.5's for back up. I read the same thing you're talking about with going to low on the PV.
The carbs are new out of the box from Carl's Ford (the matched set of 600's for the Shelby 2x4 setup), so they've never been apart (besides me taking them apart last night). I'll check the air bleeds and the re-set the float levels. Any advice on how to set the float levels on the bench ?
Thanks, Jim
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I think I'd be suspicious of the O2 sensor reading. 8:1 is at the very bottom of the scale. How does it read under full throttle acceleration, is that number reasonable? While you are seeing 8:1 on the O2 sensor, are you getting black smoke out of the exhaust? If you were really that rich, the engine ought to be stumbling, and you should be seeing a bunch of black smoke.
Jay,
The O2 is a digital Innovate 3844 MTX-L. I'm going to see if I can download the info today from my short run. This was the first time out with this car after a 7 year restoration and I was paying more attention to odd sounds, rattles, etc. I also was a bit nervous about getting into it too hard in my neighborhood but I did rap the throttle to the floor once in 2nd gear as it was in good 15-20mph roll and it fell on it's face. It was only a rap of the throttle and I didn't intend to stay in it, just wanted to see what it would do. I don't really have a place to test the car nearby and would have to make a short burst on a fwy on-ramp for any full throttle info. I didn't look out the back to see if it was blowing dark smoke but when the throttle is rapped in the shop, it doesn't smoke at all. It also doesn't stumble under light to moderate throttle.
I only glanced at the O2 a couple times and could see it drop to the 9:1 to 8:1 under light/moderate load. I only once gave it about 1/2 throttle but it was a short period and I was paying more attention to the road. I'm changing the springs on the throttle and replacing the throttle rod with a billet type with those ball bearing ends as it currently feels like it binds.
Would you setup both carbs the same on this application with the progressive linkage setup I have ? I'm going to swap out the PV's for 5.5's and then give it some more testing so I can provide more info for you guys. Would you recommend re-sizing the jets for the new PV, or just run the 64's. I know this is the beginning of pulling these carbs on/off many times and expect that timing and other factors will come into play, I just want to reduce the nasty fumes a bit and get it somewhat close for now.
I apologize to all you guys for not having more info and will re-test once I change the PV and see what I can download off the O2.
Thanks, Jim
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The reproduction carbs are nice enough parts, and are the right pieces for a restoration application. That said, they tend to be very rich on the dyno - knowing what they are I would not be afraid to pull several jet sizes out - maybe pull four and see how it responds. I have run those all the way down into the 57-59 range with good data....
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The reproduction carbs are nice enough parts, and are the right pieces for a restoration application. That said, they tend to be very rich on the dyno - knowing what they are I would not be afraid to pull several jet sizes out - maybe pull four and see how it responds. I have run those all the way down into the 57-59 range with good data....
Thanks Barry,
Would you set both of them up the same with the progressive linkage setup ? And do you think I should drop the jets to say 60's or 62's with the PV change this time or see how it reacts to just the new PV ?
I'm running a Comp Hyd roller 635/633 lift, 248/252 dur w/108 center, 112 lobe separation. You've probably built my similar setup plenty of times. I can provide more info if needed.
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I was also wondering if you guys have any recommendation with squirter size ? I'm currently running the standard type w/o the nozzle and they're 31's on both carbs. I plan to purchase the nozzle type squirters and was wondering if I should go up or down in size or keep them the same ?
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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.
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Have you pulled the spark plugs to confirm this??? Lets see the spark plugs. This will be the true indicator on whats going on here... Just my thoughts....
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I am no expert but you better not be using 110 leaded gas it will kill the O2 sensor in no time!
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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.
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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.
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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.
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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 ?
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Racers will often just use the O2 sensors in a "test" only mode - make a pass, log the data and remove the sensor after.
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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.
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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.
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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.
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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
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Jim
Just a thought have you verified that all float levels re correct ?
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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 ?
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could very well be but i would verify float settings are correct before any carb alterations.
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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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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/
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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.
+1
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Thanks for all the comments guys, I truly appreciate the help.
Finally figured out how to reduce the size of the pictures from my digital camera. Here is a pic of the #4 plug. The #1 plug looked the same.
Let me know what you guys think.
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I am sure you have done this, but ignition timing must be set before any tweaking on the carburetor. Just trying to cover the basics first.
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What are you running for an ignition? Doesn't even look like its trying to burn that plug clean
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I am sure you have done this, but ignition timing must be set before any tweaking on the carburetor. Just trying to cover the basics first.
Yep, set at 40 degrees at 3-3.5k rpm. I may back it down to 38 as it's straining the starter a bit.
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What are you running for an ignition? Doesn't even look like its trying to burn that plug clean
MSD 6AL with MSD distributor. The vacuum advance is plugged. Everything is new. It might be a faction of total run time as it's spent more time idling that any thing else.
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I realized we are talking about mixture here but I went back and tried to see what plug you're running. I didn't find if you said.
My 441 has to do lots of idling in traffic so I use a hotter plug (45s) and they stay very clean.
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I realized we are talking about mixture here but I went back and tried to see what plug you're running. I didn't find if you said.
My 441 has to do lots of idling in traffic so I use a hotter plug (45s) and they stay very clean.
I'm running NGK R BKR6E plugs. The car is a weekend warrior and rarely gets driven but if it does, it's on the street only, not in traffic. Looks to be in the middle of the heat range, nothing special.