INNOVATE DLG1 Wideband O2 Oxygen Sensor Tuning Diagnostics Logging Air Fuel Ratio etc

[Gregski]

the gauge will cycle from the HTR / HTR reading to the CAL / HTR as it calibrates the first sensor than to CAL / CAL with both sensors calibrated and finally show a AFR ratio 22.4 / 22.4

[rusty76]

I'm in for the trip. Might as well try and learn me sumthin.

[Gregski]

Now before I share my AFR readings with you allow me to introduce you to my carburetor as it will be the focal point of these tuning exercises

like most trucks mine originally came with a spread bore Rochester Quadrajet (spread bore meaning the two holes in the front under the carb are smaller than the two holes in the back of the carb) and I must admit the more I learn about carburation the more I respect the design of the Quadrajet (and yes it is probably the most misunderstood and mis configured type a carb out there, ha ha)

anyway I just had to have a Holley so I went out and bought one, a Classic Holley they call it, and at the time I thought all Holley carbs were created equal, well sure some had manual chokes and others had electric, some had vacuum secondaries others had mechanical secondaries, and there were the two barrel and the four barrel, but isn't a Holley carb a Holley carb, well no, more on that later

So I ended up with the 4160 Model - pronounced not as good as the 4150 ha ha

You would think if the 4150 is a good carb than the 4160 must be better, no, that's apparantly not how it works, I think Holley built on the success of the highly tunable 4150 and offered us (common folk aka amateur daily drivers) the "economical" 4160

My Classic Holley Specs
Model: 4160
Part Number: 0-80457SA (S for Shinny, A for Aluminum)
Main Jets: 65
Secondary Metering Plate: Main Hole 0.055, Idle Hole 0.026
Barrels 4
Booster Straight
CFM 600
Choke Electric
Circuit 2
Fuel Inlet Single
Secondaries Vacuum
Throttle Bore 1.563 inch

[Gregski]

without preaching about carbs, let me point out the difference between the 4150 carbs and the 4160 as it may effect our tunability capabilities, and even require us to convert our 4160 into the 4150 (it's duable folks)

in technical terms, what's the difference?

well simply put the 4150 has something called a metering block in the front (between the front float bowl and the main body) and another one in the back (between the rear float bowl and the main carb body) (a metering block is what holds the main jets, etc) a 4160 only has one metering block in the front, and something called a metering plate in the back (you can't screw in different jets into a plate, hence the limitation you have to swap out the entire plate but its not the same granularity as you would have with changing jets)

first pic is of the metering block (thickness of a wallet)

second pic is of a metering plate (thickness roughly that of a credit card)

[Gregski]

we're going to be looking for optimal Air Fuel Ratios in four different throttle positions

1. Idle - completely no foot on the gas pedal (truck is idling in the garage or you're sitting at a red light), think Idle Mixture Screws

2. Cruising - we are traveling at highway speeds foot resting on the gas pedal holding it steady, sometimes refered to as Part Throttle

3. Accelerating - stepping on the gas pedal, all the way up to WOT - Wide Open Throttle, think Accelerator Pump, Power Valve and Main Jets

4. Decelerating - letting off the throttle

[AnotherWs6]

ok. waiting.

[Gregski]

Originally Posted by AnotherWs6

ok. waiting.

sorry, alright

IMPORTANT: the vehicle must be fully warmed up first, so this is after letting it sit and idle in the garage for 15 minutes (it would have been better if I took it for a short drive also, but I was blocked in the garage by other vehicles, blah blah blah)

Idle = 10.6 (Left Bank aka Driver Side) / 11.00 (Right Bank aka Passenger Side)

Gentlemen, this is not good, this is too rich. But keep in mind my truck runs great and drives great, heck it even sounds good. Hmmm makes you wonder

The goal is between 13:1 and 14.7:1 with the highest vacuum you can get at idle.

[Gregski]

took the Geek to the next level, and connected my Netbook to the AFR gauge, this allows me to not only log the data and graph it, but you can create virtual gauges on the computer so if you want you can tap into your Tach and see RPM, very cool

it beats asking your buddy to ride shotgun and take notes as you drive your test circuit, ha ha

[AnotherWs6]

Interesting. I purchased two analog gauges. I said schme to datalogging, but now I'm thinking twice. I'm not sure of mine can log or not, but being able to log WITH rpm seems pretty important.

(I was thnking of using the buddy method for initial tuning)

[Gregski]

Idle Circuit Adjustments

I had four things to check / adjust to make sure my Idle AFR was in the proper range:

1. Float Levels

2. Idle Speed Screw / Transfer Slot

3. Idle Mixture Screws

4. Idle Air Bleeds

[Gregski]

Setting the Float Levels

My 4160 carburetor does not come with site glasses (pronounced: sucks) so I had to unscrew the site plugs in the float bowls and see if any gasoline was pouring out (similar concept to topping off a manual transmission, you fill it with fluid until it just barely pours out of the filler hole type a thing)

So you adjust the Adjusting nut and Lock screw on the top of the float bowl, than you rock the truck a little bit with your hips and you watch the site plug for the fuel level, rinse, lather, repeat

my float levels were good

[Gregski]

Adjusting the Idle Speed and Idle Mixture simultaneously (it really takes Two To Tango here)

so the recommended starting point for most carbs is 1.5 turns out from bottomed out, in other words Idle Mixture Screws all the way screwed in, mine just happened to be set there - one and a half turns out they were

Note: my four barrel carb has two Idle Mixture screws one on either side of the front float bowl, some fancier carbs have four Idle Mixture screws, two in the front float bowl like mine, plus two additional screws in the rear float bowl as well

my truck was set to idle at 700 RPM - aka the Idle Speed screw (which does not just control RPM but opens / closes or hides and exposes something called the transfer slot(s) (ubber important)

the recommended setting is .020" or making the slot look like a little perfect square (Note: it is over exposed in the picture below, in other words it is too large) the pic below is just an example it is not my actual carb

[Gregski]

twisting and turning the Idle Mixture screws and the Idle Speed screw is a bit of an art and a science as one may and does effect the other

TEST 1 - I set my Idle Mixture Screws only 1 turn out

AFR Reading: this improved my ratio from 10.6 to 11.6

RPM: this raised my revolutions from 700 to 900

ok, cool, now what?

well the engine was now idling a bit too high (for my taste anyway) so we dropped it using the Idle Speed screw back down to 700 RPM, noting that the AFR stayed the same

[Gregski]

well things were better but I kept going

TEST 2 - I set my Idle Mixture Screws only 1/2 a turn out

AFR Reading: this further leaned out my air fuel ratio from high 14s / low 15s (a bit too much)

RPM: this is where it gets interesting, my revolutions dropped from 700 to 600, wait a minute, last time we leaned things out and the revs went up, and this time we leaned things out some more and they dropped? yup, that's how it works, once you pass the sweet spot the carb tells you it aint happy any more

[Gregski]

so lets do one more try

TEST 3 - I set my Idle Mixture Screws about 3/4 turn out

AFR Reading: this put my air fuel ratio at around 13.5

RPM: revolutions landed at 750

I was happy with that for now so I took the truck for a test drive and to log some data

[Gregski]

now when I started to go on my test run, my truck was idling at 13.5 AFR by the time I came back from the test drive it richened back down to 12.5 (???)

I recall reading somewhere that the Idle Mixture screws should be somewhere between 1/2 a turn and no more than 4 turns out, so I was approaching that lower limit of 1/2 a turn to lean it out, but before messing with the Idle Air Bleeds (which I am not even sure I can replace on my carb to be honest with you) I decided to remove the carb and use my EyeCrometer to inspect the transfer slots (something you can't see with the carb on the truck)

[Gregski]

ok so with the carb off and sitting on the work bench upside down we can see that my primary transfer slots are about twice as big as they should be, to me they look like rectangles rather than proper squares

Interstingly enuff there are no slots exposed at all in my secondaries?! is this what is forcing the primary slots to be twice as big? are they compensating for the non existant / non contributing transfer slots in the secondaries?

primay butterflies are the black circles

secondary butterflies are the gold circles

[AnotherWs6]

Loving this. I know there are some guys that can tune a carb based on knowledge and feel etc, but I think I fall in the category that most do - I can KINDA tune a carb based on the same things and some internet research! Throwing accurate gauges into the mix just changes the game. It takes out the "I think" and "It feels/sounds/smells like" and replaces that stuff with cold, hard facts. Thanks for taking the time to write this stuff up in such detail.

Question - how much is your AFR bouncing around n general at idle and cruising? I imagine that at WOT it is fairly steady (correct me if I'm wrong) but is it doing a dance otherwise? Again, I went with analog gauges so I'm concerned with being able to get good part throttle readings once installed. You know? If it's bouncing all back and forth from 15 to 11 it's going to be tough. I had an Autometer unit that tapped into the factory O2's on a 91 5.0 many moons ago and that thing danced all around unless you floored it. We are talking about a whole different kind of accuracy with dedicated widebands and modern technology, but if you were trying to tune a carb with the readings that that thing got you would probably throw it out of a window fairly quickly.

[Gregski]

Originally Posted by AnotherWs6

Loving this. I know there are some guys that can tune a carb based on knowledge and feel etc, but I think I fall in the category that most do - I can KINDA tune a carb based on the same things and some internet research! Throwing accurate gauges into the mix just changes the game. It takes out the "I think" and "It feels/sounds/smells like" and replaces that stuff with cold, hard facts. Thanks for taking the time to write this stuff up in such detail.

Thank you for the positive feedback, makes it worth while for me to stop and take pics all the time and document every step of the way, the gauges are so accurate and so sensitive that they show changes otherwise undetectable to the human eye, ear, or nose. For example barely moving the idle mixture screws like 1/16th of a turn changes the AFR by over half a point without even changing the RPMs, I don't want to start World War III or nothing but I am willing to bet many of the tune by Long Screw Driver To The Ear mechanics of yesteryear were most likely way off and either not getting the fuel economy they could have and or leaving plenty of horse power on the table

hugs
G

[Gregski]

Originally Posted by AnotherWs6

Question - how much is your AFR bouncing around n general at idle and cruising? I imagine that at WOT it is fairly steady (correct me if I'm wrong) but is it doing a dance otherwise? Again, I went with analog gauges so I'm concerned with being able to get good part throttle readings once installed. You know? If it's bouncing all back and forth from 15 to 11 it's going to be tough. I had an Autometer unit that tapped into the factory O2's on a 91 5.0 many moons ago and that thing danced all around unless you floored it. We are talking about a whole different kind of accuracy with dedicated widebands and modern technology, but if you were trying to tune a carb with the readings that that thing got you would probably throw it out of a window fairly quickly.

Just because you went with the Analog gauges (and I am not sure which exactly) but it don't mean you can't data log, so please post your specific make and model and part number on this thread this is to help everyone out and we will check if they can, I think they sure can

keep in mind you need to be tuning a sound engine and by sound I mean working properly, all in order, so no VACUUM LEAKS, no oil leaks, NO VACUUM LEAKS, no coolant leaks, and did I mention NO VACUUM LEAKS, ha ha, valves adjusted properly, and your spark plugs gapped properly, wide gap for H.E.I. distributor if you got one, .045(ish) all plugs exactly the same gap, all plugs the same brand, and none of them fancy Unobtanium ones just good ol's stock AC Delco or what ever the manual recommends, every single plug wire checked for proper resistance Ohms and within spec, if not get new ones, just because you buy new plug wires don't mean they are all good, (ask me how I know)

to check for vacuum leaks, simply isolate the problem, label every vacuum hose before you pull it off with blue tape, for example Dist Adv, Brk Boost, AC, blah blah blah

then go out to the store and get yourself some black rubber port plugs and plug every single port on the carb, every one, you don't even need vacuum advance at idle

this will eliminate your PCV Positive Crank Case Ventilation valve from leaking, your Power Brake Booster vacuum line leaking, your anything else vacuum hose from leaking

DISCLAIMER: now I aint trying to micromanage you I am just trying to help with as much specifics as I can offer

[Gregski]

Transfer Slot Adjustment (using the Idle Speed Screw... it's not just for mocking with the RPMs you know)

so we need to make the transfer slot look like a square, easy to do with the carb off, but how do we get back to a square after messing with it on the truck

well on my carb I figured out that after I gently bottom out the Idle Speed screw it takes 7 turns to undo it to the point where the transfer slot disappears completely, so that gets us half way there

then it just so happens that if I turn the screw in 1.5 turns we get a perfect square

hey 1.5 (kinda like the idle mixture screw) even I can remember that

so now with the carb on the truck we know how to get back to a square if we have to, (try it on yours with the carb off first as your mileage may very)

just trying to show you it from different angles in the pics, hard to do this with one hand holding the camera etc as a one man job

[Gregski]

and so my little 600 CFM 4160 type carb is baselined

- both idle mixutre screws 1.5 turns out
- primary transfer slots set to show only a .020" square

here I am just showing off my measly 65 main jets (after I removed the front float bowl)

and the 45R-312 boosters

[Gregski]

Oh O

well one thing you will notice with me is that I am honest and I share the good and the bad, the bad and the ugly, so I must share with you that I lost my first two Data Logs because the LogWorks software crashed when I merely clicked on the X axis in the graph in an attempt to change the legend a bit to zoom in on the numbers, but oh well, live an learn, and I do have a third Data Log so we can look at that one later

anyone else using this software and realizing some problems with it?

[Gregski]

Idle Test Results after Bench Tuning the Holley 4160 Carburetor

Wow, fellers what a difference resetting the carburetor to factory/recommended specs has made and understanding why and the impact

BEFORE: 10.6 (Left Bank aka Driver Side) / 11.00 (Right Bank aka Passenger Side) Too Rich

AFTER: 13.6 / 13.8 aka Almost Perfect

RPM: 550(ish)

now we could do better and strive for 14.7 but keep in mind there is a balance between Prius like fuel economy and In Yer Face performance, ha ha - so the numbers we see above are pretty darn good for now, plus setting the Idle AFR is only the tip of the ice berg, we shall take a look at Cruising AFR next

check out those read outs... nice! excuse you me while I sprain my elbow patting myself on the back - ha ha

[Gregski]

Originally Posted by AnotherWs6

Question - how much is your AFR bouncing around n general at idle and cruising? I imagine that at WOT it is fairly steady (correct me if I'm wrong) but is it doing a dance otherwise? Again, I went with analog gauges so I'm concerned with being able to get good part throttle readings once installed. You know? If it's bouncing all back and forth from 15 to 11 it's going to be tough. I had an Autometer unit that tapped into the factory O2's on a 91 5.0 many moons ago and that thing danced all around unless you floored it. We are talking about a whole different kind of accuracy with dedicated widebands and modern technology, but if you were trying to tune a carb with the readings that that thing got you would probably throw it out of a window fairly quickly.

hope this graph helps you out, this is a pretty darn good Idle AFR of my truck just sitting there running in the garage for just over a minute after it has been warmed up already, I think it's somewhere between 13 and 15, sorry about the tiny graph I am still trying to learn the software aka the scale adjustmentability