Dave,
I was told to do a test last night to check the heater on the sensor to see if it was heating properly. I turned the key to the "run" position for at least 30 seconds, and I was told to touch the body of the sensor for some heat. I did that and the sensor was still as cool as it was when I moved the key, even after about a minute with the key in that position. I made this test twice with the same result, so I pulled the sensor. The sensor does have carbon on it, but like yours, the holes are not covered and it can wipe off.



Note: I do not have any power on check routine unless it is built into the FAST system. I run unleaded pump gas and the sensor is plugged in full time. I may have just gotten a bad sensor.

Thanks for the reply.

UPDATE:
I talked with FAST tech support and I need to ship them the unit back for full inspection. It looks like I am out of the O2 game for a while.

Sorry to hear of the trouble, but it's good the manufacturer will look at the unit for you. Hopefully you'll get it back together soon!

Dave

JimG,

I am impressed and greatly appreciative of your insights. This weekend I ran the experiment which you suggested. I dropped the float a whole lot...about 1/2" or so, and the fuel level was noticeably below the bottom of the sight glass. The motor ran much leaner, in fact so lean that I was worried. At 2K RPM, I was seeing AFR in the high 15's to low 16's at light throttle. At 3K highway speed the AFR was richer but still in the 14's. The really lean mixture worried me some, so I switched the IABs from .072 back to .070, and this helped; I didn't see excursions of AFR into the 16's anymore.

The question is "why did help so much". Check out the attached image. The original fuel level is at the bottom of the top piece of tape (mid-sight gauge). Just as you suggested, the fuel level was right at the bottom of the first e-bleed. Given the motor vibration and road quality surface, it is easy to imagine that the fuel was at times covering and uncovering this bleed hole. This is likely the cause for the AFR swings.

The very low float level is marked by the top of the bottom piece of tape. This would have put the fuel level a little above the 3rd e-bleed. Note that the jets you see in the picture are blanks.

But now there is still a mystery. I was not happy with the float as low as it was, and decided to raise it up some. I moved the adjuster 1.5 flats, and that brought the fuel level right to the edge of the bottom of the sight glass. This had a very noticeable effect on the AFR, with 2K cruise now in the low to upper 14's. So it changed the AFR by at least 1 point. Highway speed is now solidly in the mid-13's. The mystery is why did it have such a big effect? It looks like the 3rd bleed would have been covered with the very low float, and now the fuel level should be right in the middle of the blank e-bleed. Perhaps with fuel slosh, the very low float setting was allowing some bleed air in???

As I mentioned before the factory setup had the top 2 e-bleed open (drilled to .028), with a blank in the third, and the fourth open. Having the upper 2 allow some bleed air now seems reasonable, but I feel that 2 .028 bleeds is too much. At the moment, I am considering drilling the second bleed to allow some air in, perhaps something like .020.

In my next post, I will show the comparison of the QF 4 e-bleed metering block with an old Holley one.

Dave

OK, here is a view of metering block from an old Holley 780VS. If the fuel level was set to the bottom of the sight glass, then it would have been covering both e-bleeds. The only bleed not covered is the kill bleed. Does the kill bleed affect the AFR?

On my QF metering block even though the top e-bleed was not anywhere near covered with the second and third float level I tried, the carb still ran noticeably rich at highway speeds.

Next up, a comparison of the two metering blocks.

Here is the comparison between the two. It appears the top e-bleed is in almost the same position (height). The 3rd e-bleed on the QF block appears to line up with the 2nd e-bleed on the Holley. I think my current setup is darn close to the old Holley setup.

The kill-bleed on the QF is lower than the Holley. Would that have an effect? The kill-bleed is also smaller on the QF.

As I mentioned, I am now considering adding some bleed air on the second e-bleed by hand drilling a jet. Do you have any thoughts on this?

Thanks,
Dave

I have the FAST kit back and I have been running it for a couple of weeks now and I have a quick question.
I noticed that when I take my foot off of the accel pedal at a cruising speed (A/F readings 14.4-15.4) and the A/F gage goes richer into the mid to low 13's. What causes the richer A/F reading on decel?

Thanks

Y07_A06

Glad to here your wideband is back in action!

Can you remind us what your AFR at idle? When the throttle closes, the vacuum level is likely going very high, and pulling more fuel thru that circuit. I doubt there is much that can be done about that on a carb.

Question for you....how much does your AFR change immediately following a gear shift?

Regards,
Dave

Thanks Dave. I am glad to have it back.

I have been able to do plenty of testing with my N idle/in D idle and what I have found is that my setup idles best in the 13.5-13.8 range in D. I had the D idle setup to 14.0-14.2 (couple of times with different outside temps) and it idled too choppy and the rpms were moving around too much at a stop sign/light. I have also found that my N idle numbers are usually in the same range as the in D A/F ratio once I move the gear selector from D to N after it has been driven and up to temp. The rpms still go up once it has been changed from D to N, but the A/F stays pretty close.
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""When the throttle closes, the vacuum level is likely going very high, and pulling more fuel thru that circuit. I doubt there is much that can be done about that on a carb.""
- That is what I was assuming but I was not sure. Thank you.
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""how much does your AFR change immediately following a gear shift?
- During light accel to cruising speed, I do not recall much of a fluctuation in A/F readings. From gear to gear at WOT, I have not tested that one. I have only tested WOT from cruise until the car shifts at the WOT shift point, then I let go and take my notes. Once I get my pumps dialed in, I will check that out.
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Speaking of getting my pumps dialed in, what A/F number should I be aiming for under light accel and medium accel (before the power valve kicks in)? I am currently getting 13-8 to 14.2 depending on the cruising speed. The idle accel (from a stop) seems to be in the 13-8-14.0 range and my cruising accel seems to be in the 14.0-14.2 range. This seems a little lean to me, what do you members suggest?

Thanks to all.

Guess what? After 7 more drives after re-installing the A/F kit, it died,,again. It is now back at FAST and they say that they have never seen this trouble with one of these units before. Last time they said that they did not find any issues with the unit and it was due to my wiring. But when I told them that I had power at both of the 12v leads, they said that it was still by wiring. So I wired it back in and it ran fine for a short time again. Anywho, the same problem happened again this time as it did four weeks ago. So I am waiting on them to call me and it is still under full warranty. I am waiting patiently to see if they find anything wrong with it this time.
But during the seven drives, I was testing the cams/squirters trying to get my off idle accel and my cruise-WOT A/F ratios to fall into place. I did not finish before the kit took a dump, but what I did notice was that the different pump cams that I was using sure do make a huge difference in the A/F ratio. I was running a pair of Red cams and from 50-55mph cruise to WOT, the A/F ratio dropped to 12.5 for a second and then leaned out to 13.0 at my shift point. I wanted to lean this out to the upper 12's and started changing out squirters. The squirters did not do anything to the A/F number (secondary side: 25, 31,35,37) so I started swapping out cams. I tried swapping in the secondary cams and retesting and found a minor A/F change from red, black, and pink which all gave me about a 12.0-12.2 A/F reading with the red primary cam. So, for the fun of it, I swapped out the primary cam to an orange and found a huge A/F change that showed a dip to 11.0 at the cruise to WOT. These changes do reflect the Holley pump cam chart that I have been referencing for the past 3-4 years. I know that there are a few of these charts on the internet and now I have proof that I am using the correct chart.
I am finding out that I need the smallest black cams to keep my cruise-WOT spike in the upper 12's. I am now using a black/.037 on the primary and once I get the kit back installed, I will be testing with the black cam on the secondary side with a 031 squirter. I am hoping that this change gets me into the upper 12's but if it does not, then I am going to test with a scondary linkage change that Quick Fuel provides with their DP carbs. I am currently using the linkage that allows the secondaries to come in at 40% throttle and if I have too, then I will delay it with the 60% throttle link. I remember when I ran a vacuum secondary carb that this combo liked the heaviest brown spring. Maybe it will like having the secodaries coming in later with the 60% delay too.
I will check back in when I get my A/F kit re-installed and I have more tuning time.
If any of the members have some A/F numbers to provide along with their pump cam tuning, please feel free to tell us how the tuning came along.

Y07_A66

The target AFR during light acceleration is a great question, and one which I don't have any firm thoughts on. It should certainly be leaner than WOT AFR. There is not much load during light acceleration, and I would be too surprised if keeping it around 14.7 is acceptable. The best answer is probably to see what a modern factory EFI system does. Does anyone have insight into that?

I asked about the AFR immediately following a gear shift because on my car I have noticed a significant transitory lean condition after a shift on light acceleration. Its almost like the carb looses its metering ability for an instant when the RPMs drop. I'm not that concerned about it, but when the motor is not to full operating temp, I can actually feel it go lean (besides seeing it on the wideband).

I'm sure you're frustrated with the wideband problems. I know a guy whose LC-1 went wacky during a road race, but hadn't heard what the final resolution was.

I'm not sure if the different progressive ratio on secondaries will make much difference on the AFR. When going to WOT, the difference in opening time between primary and secondary is going to be pretty darn close. I thought the advantage of the different ratio was during moderate throttle conditions, where avoiding hitting the secondary accelerator pump can help. The VS secondary carb likely had a much more noticeable difference in timing of opening between pri and sec, and obviously doesn't have the extra fuel from a secondary accelerator pump.

Your accelerator pump cam tests sound like they are going in the right direction, and this "knob" will likely get you to where you want with sufficient experiments.

I don't have a lot of info to share on pump cam affects. On my motor, virtually all of the cams have been insufficient, with a big lean spike on the WOT transition. I have had to go to the biggest cam (blue) and currently have a 0.035 squirter. I purchased a 50cc pump, but unfortunately it has interference with the RPM DP, so for now I am sticking with the 30cc pump. My WOT AFR still needs tuning, and is a bit on the rich side. I'm trying to strike a balance between high speed cruise and WOT mixture and am still playing with the PCVR and main jet relationship.

Hope you get your wideband sorted out soon!

Dave

""I purchased a 50cc pump, but unfortunately it has interference with the RPM DP, so for now I am sticking with the 30cc pump.""

I tried a 50cc on my RPM intake with a different carb. I found the same interference so I added a heat spacer under the carb which gave me enough space to run the 50cc unit.

I had my light throttle accel around 14.0 but it seemed lazy and the exhaust sounded funny. As soon as I richened it back up into the mid 13's, it ran better. I am currently getting 13.4-13.6 for my light accel from a stop and it feels right (black/037 primary).
FAST found the problem this time and they are sending me a new kit. Their warranty manager said that he has not seen an analog kit fail like this one before. The processor was overheating causing the system to read 14.6 which is a typical reading if there is a fault in the kit. It also appears that their first repair on this unit was not performed properly and they sent it back to me and that it why I found the problem for the second time. I should have it back in the car next week and I can continue on the cruise to WOT rich spike.
Your thought on the secondary rate sounds correct. The linkage moves pretty darn quick during a WOT change and the secondary delay may not help. Good point.
I have a feeling that if the two black cams together (leanest cam setup) does not work, then I might test what a standard power valve does versus my current High Flow power valve which QF suggests to use with their carbs. The current opening rate is a 9.5 which works well under all of my cruise conditions and the WOT transition, but maybe the four door design is dumping too much all at once when the valve opens.

Thank you Dave.

GREAT STUFF GUYS PLEASE KEEP IT UP!!!!!

I may try a spacer to allow the 50cc pump, but my hood clearance is pretty darn close, so I have been doubtful that it would still close, at least with my current air filter. I don't like running too short of a filter with a drop base since the lid gets sort of close to the top of the venturi. At the moment, I still have some hope that the 30cc pump will just be enough.

If you still have a rich dip after going to two black cams, then you might want to try decreasing the squirter size again. Now that the cam is about right sized, you may be able to see more sensitivity to that. You may be right about the PV having an effect on how quickly that extra fuel gets introduced, but I don't have any experience to draw on there.

Look forward to hearing more!

Dave

Dave,
I have another thought on my 50/55mph to WOT rich spike. After reviewing my latest chart, my primary jets are still a little rich. This is what I show with the same outside air temps:
70mph (3500rpms) = 13.6 A/F with 65 primary jets
70mph (3500rpms) = 13.8 A/F with 64 primary jets
I am going to swap in some 62 primary jets to see if I can lean out the 70mph cruise to get into the 14's. If this works, this should lean out my 50/55mph to WOT rich spike a tad. Then I will make a secondary squirter swap (currently Black/031") to lean it out some more if needed. I have .028", .025", .021", and .019" squirters to test.
If this does not fix it, then I will pull the high flow pv and swap in a standard pv of the same rating.
Our outside temps are now in the mid 90's so the A/F may not lean out enough.

Note:
FAST found an internal heating issue with my last A/F unit and they sent me a new complete kit. I have it installed and now I just need to get my tale out in the heat and test some more.

Thanks for the reply.

Y07_A66:

I wonder if that rich dip in your fuel curve is due to overlap of the transition circuit and the main. At 3500 the motor may be pulling decent amount of fuel thru the mains while the transition is still flowing a noticeable amount. Above that point, the transition may be flowing less and the mains more. Leaning the main jet will cause your 4K RPM to be leaner as well, and some care may be needed to balance between getting it perfect at 3.5K and having it too lean above that.
The main jet change will obviously lean up the WOT AFR as well.

Sometime back I realized my motor is also pulling fuel thru the mains at 3K cruise, contrary to my original thoughts. If I went really lean on the mains, the 3K cruise AFR can be improved. Geting the right balance is going to be some work though. However, last weekend I pulled the intake again, and confirmed I am still getting oil into the runners, so I need to resolve that before tinkering any more.

I'm glad you are back in business with the wideband. Your motor seems like it is running like a fine clock. My wideband has been fine so far, but I'm lacking on the motor side. Hopefully soon we will have both motor and wideband working well at the same time!

Dave

""I wonder if that rich dip in your fuel curve is due to overlap of the transition circuit and the main. At 3500 the motor may be pulling decent amount of fuel thru the mains while the transition is still flowing a noticeable amount.""
- You may be right. I never thought of both circuits still pulling at the same time.

""Above that point, the transition may be flowing less and the mains more. Leaning the main jet will cause your 4K RPM to be leaner as well, and some care may be needed to balance between getting it perfect at 3.5K and having it too lean above that.""
- My chart shows that the higher up in the rpm range the richer the carb is getting:
64 jets, 2700rpms: 14.6 A/F
64 jets, 3000rpms: 14.4 A/F
64 jets, 3500rpms: 13.8 A/F
64 jets, 4000rpms: 13.6 A/F
I changed out the primary jetting last night to the 62's from the 64's. The 4000rpms A/F could use less fuel too. I also swapped out the 9.5 Hi Flow power valve to a 8.5 Standard power valve too while I had the metering block off. I want to see how rich it gets at 50/55 cruise to WOT with the standard pv in it. My standard 9.5 felt a bit too strong versus my Hi Flow 9.5, so I opted for the next lower unit of 8.5. (I know, one thing at a time. But the wideband is showing me two different issues to fix. I believe that the leaner primary jet will help out the 3500-4000rpm cruise while the standard pv will help lean out the rich spike at a cruise to WOT.)


""The main jet change will obviously lean up the WOT AFR as well.""
- I currently have 75's in the secondaries and my WOT with the 64's in the primary side did not go leaner than 13.0. I will keep an eye on the WOT AFR now with the 62's in front.

Thanks a bunch for your response. I might wait until the weekend to test it out due to our current heat wave of upper 90's.

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""However, last weekend I pulled the intake again, and confirmed I am still getting oil into the runners, so I need to resolve that before tinkering any more.""
- Is this just a gasket or is there more to the problem?

Y07_A66:

The oil in the intake runners is hopefully only a gasket issue! As you probably know, the big block uses an integrated valley cover and intake gasket made of metal. This works fine with with cast intakes and heads, and the higher torques applied when those are in use. With the aluminum intake and heads and lower torque values, there appear to be mixed results. Some will state they have had no issues with just the tin gasket, others will say you need to use paper gaskets in addition on one or both sides of the tin. To add to the situation my block has been decked which slightly changes alignment.

The other variable is gasket sealer, and again there are lots of opinions and testimonials to what works and what doesn't, with no clear consistent results. Originally I had paper gaskets on both sides of the tin gasket, because I was concerned about the effect of the block decking. Last weekend I redid the intake, and now just have a paper gasket on the intake side of the tin. Hopefully that will do the trick. Next step would be to just try the tin by itself. The final step would be to use a separate valley cover, but that would entail doing some clearancing on the bottom of the intake (trying to avoid that). My old M1 SP would clear but the RPM DP would not.

It is going to be smoking hot here this weekend as well, but I will still complete putting everything back together and take the car out for a spin to try it out. At least my motor doesn't run hot!

Dave

Update
The new FAST wideband is working fine and I was able to take a test drive with the 62 primary jets (versus 64's) and the 8.5 "standard" pv (versus 9.5 High Flow).

30mph (1800rpms) @14.4 A/F
40mph (2200rpms) @15.4 A/F
50mph (2500rpms) @15.0 A/F
60mph (3100rpms) @15.6 A/F
2nd (3500rpms) @14.2 A/F (64 jet = 13.8)
2nd (4000rpms) @14.0 A/F (64 jet = 13.6)

The 64 to 62 primary jet swap brought the A/F range up into the low 14's above 3500rpms. I think that I will leave it alone for now. I keep changing the range that I would like to be driving in but for right now, I like the 14.0 - 15.6 cruising A/F range.

The 9.5 HF PV (high flow per Quick Fuel) swap to the Standard 8.5 power valve did not help my 50/55mph to WOT rich spike like I was hoping. The rich spike stayed in the 11.8 to 12.2 A/F range. The 62 jets did not hurt my WOT A/F number, it was still at 13.0 at my shift point. It also took away from my low end power at WOT. I am going to swap back in the 9.5 HF unit and then swap my secondary squirter from the current .031" all the way down to a .018" and see how the rich spike acts.
The above was done in 80 degree temps with very high humidity. We are supposed to get into the mid 90's with high humidity, so I am done for the day.

this has been a great post. thanks for all the info. my question is a/f ratios are controled by the jets correct? and the idle mixture screws are only for the idle circuit? thanks again.

The metering screws do control the idle mixture but their settings also affect the transition circuit too.
The main jets are in the main metering circuit which help control the A/F when the main circuit is working.
You have a few circuits to deal with, idle then the transition and then the main metering circuit, then the secondary or WOT. All need to be tuned to the correct A/F range, and depending on the carb, they have replaceable jets for each circuit for tuning.