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

[Gregski]

a little feedback on this first Holley carburetor book I got and read

save your money

aside from the fact that it's from 1980 (you could argue old or you could argue at the peek of carburation, ha ha) and aside from the impossible to tell where the black pointers point to in the black and white tiny pictures what is the worst about the book is the lack of depth on anything

the author only writes a paragraph on each topic, so about 6 sentences on the idle circuit, another 6 on the main circuit, another 6 on the accelerator pump, way too little information, you will most definately NOT be able to tune nor repair your Holley carb after reading this book, ha ha

final verdict: pass on this one

[Gregski]

my second book arrived today, this one circa 2013

How To Super Tune and Modify HOLLEY Carburetors

Am I the only one to see the irony in the cover pic of what appears to be a Quick Fuel Carburetor

[Gregski]

Alright guys how hard can this be? Time to install the digital vacuum gauge

[Gregski]

First we install the Mass Air Flow meter - MAF being careful to keep it away from any electronics that may cause interference

Zip ties make for a quick install on the PCV hose

[Gregski]

Man doing this on the iPhone sucks I can only upload one pic per post no matter what browser I use, Safari, Chrome or FireFox, and to think I could do this on my old trusty Blackberry Z10

[Gregski]

Here you can see how I routed the MAF wire around the carb and in through the firewall to mate with the digital vacuum gauge

[Gregski]

ok as with any wiring installation things usually have to get uglier before they get better

we had to yank out all the AFR gauge wiring and its controller to mate it with the new digitial vacuum gauge

[Gregski]

I protect all my gauges with inline fuses, in this case the digital vacuum gauge calls for a 2 Amp fuse

[Gregski]

and there it is sitting right along the side of the AFR gauge, fits perfectly

I was a bit surprised that I was only pulling 15 inches of vacuum, thought it was much more than that

here are the specs of my GM hydraulic flat tappet camshaft

Part # 24502476

Lift: .435" intake, .460" exhaust

Duration: 212° intake, 222° exhaust @.050" tappet lift

Centerline: 109° ATDC intake, 116° BTDC exhaust

Lobe Separation: 112°

[Gregski]

alright so the whole point of getting a vacuum gauge was to tune the carburetor to have the highest vacuum at idle, so here we go


below we only mess with one thing at a time so in this case we were only turning the Idle Mixture screws to change the idle mixture, we were basically allowing more fuel in to see what the impact would be on vacuum

undesirable results are in red


-TIMING- - - - - - - - - - - - - - - - - - - - - - - - - - - IDLE - - - - - - - - -IDLE - - - - - - AFR - - - - - - AFR
ADVANCE - - - - - RPM - - - - - VACUUM - - - - - MIXTURE - - - - - - SPEED - - - - - LEFT - - - - - RIGHT - - - - - - - - - COMMENTS

- 10° - - - - - - - - -590 - - - - - - - 15" - - - - - - - -1.50 turns - - - - - -1.5 turns - - - - - 13.5 - - - - - 13.6 - - - - - this is where we started (carb bench tunned to factory specs)

- 10° - - - - - - - - -580 - - - - - - - 15" - - - - - - - - 1.75 turns - - - - - 1.5 turns - - - - - 12.2 - - - - - 12.2 - - - - - we richened the mixture by quarter turn out (vacuum stayed the same at 15")

- 10° - - - - - - - - -540 - - - - - - - 13" - - - - - - - - 2.00 turns - - - - - 1.5 turns - - - - - 11.4 - - - - - 11.6 - - - - - we richened the mixture by another quarter turn (vacuum dropped to 13")


ok, alright, clearly we are going the wrong way, the mixture is getting richer and richer, ok now we know (and we couldn't lean it out any more cause that would drop the RPMs below 500 and the truck would die)

[Gregski]

ok, so we return the carb back to the bench tune of recommended factory specs, Idle Mixture 1.5 turns out and the transfer slot .020" showing (little square)


and now we only mess with the Idle Speed screw to change the idle speed / transition circuit (the infamous transfer slot), we were basically raising the RPMs to see what the impact would be on vacuum



-TIMING- - - - - - - - - - - - - - - - - - - - - - - - - - - IDLE - - - - - - - - -IDLE - - - - - - AFR - - - - - - AFR
ADVANCE - - - - - RPM - - - - - VACUUM - - - - - MIXTURE - - - - - - SPEED - - - - - LEFT - - - - - RIGHT - - - - - - - - - COMMENTS

- 10° - - - - - - - - -590 - - - - - - - 15" - - - - - - - -1.5 turns - - - - - -1.50 turns - - - - - 13.5 - - - - - 13.6 - - - - - this is where we started (carb bench tunned to factory specs)

- 10° - - - - - - - - -640 - - - - - - 15/16" - - - - - - 1.5 turns - - - - - -1.75 turns - - - - - 13.3 - - - - - 13.5 - - - - - we increased the RPMs by a 1/4 turn in (vacuum went up to 15/16")

- 10° - - - - - - - - -750 - - - - - - 16/17" - - - - - - 1.5 turns - - - - - -2.00 turns - - - - - 13.1 - - - - - 13.2 - - - - - we increased the RPMs by another 1/4 turn in (vacuum went up to 16/17")


ok, so now we are going the right way the vacuum is creeping upwards a little bit and the AFR is staying the same for the most part ~ I think we are learning it will take a little bit of both Idle Mixture and Idle Speed screw adjusting to find the sweet spot with the highest vacuum, hey nothing we didn't know already, but now we have a vacuum gauge validating what we are doing, seeing, smelling, and hearing

[Gregski]

ok so after mocking with just the Idle Mixture screws and then just with the Idle Speed screw, it was now time to mess with both

so for this part we leave the Idle Speed screw at 2 turns turned in (so 1/2 a turn beyond the sweet spot of exposing just a .020" transfer slot)

-TIMING- - - - - - - - - - - - - - - - - - - - - - - - - - - IDLE - - - - - - - - -IDLE - - - - - - AFR - - - - - - AFR
ADVANCE - - - - - RPM - - - - - VACUUM - - - - - MIXTURE - - - - - - SPEED - - - - - LEFT - - - - - RIGHT - - - - - - - - - COMMENTS

- 10° - - - - - - - -550/750 - - - - -15/16" - - - - - - 1.25 turns- - - - - -2.00 turns - - - - 15.x/16.x - - - 15.x/16.x - - - - when we leaned out the mixture by turning the screws 1/4 turn to only 1 1/4 out the RPMs wigged out and we were way too lean

- 10° - - - - - - - - -700 - - - - - - 15/16" - - - - - - 0.50 turns - - - - - -2.00 turns - - - - - 14.x - - - - - 14.x - - - - - this yielded a 14.x AFR but its at the 1/2 turn minimum (the minimum being 1/2 a turn the maximum being 4 turns guideline)

[Gregski]

so where do we go from here, well here are our choices

1. leave it where it's at (don't like this option cause it's right on the edge of lean with it being just 1/2 a turn out)

2. adjust the distributor advance lets say from 10° to 12° (this is free and will cost us nothing)

[Gregski]

I am going to go with option #2 and first increase the timing advance on my genuine GM H.E.I. Distributor part number 93440806 here are its specs ie advance curve

Mechanical Advance: - - - - - - - - Vacuum Advance:
- - - - - - - - - - - - - - - - - - Vacuum
RPM - - - - - Advance - - - - - (in. Hg) - - - -Advance
1100 - - - - - 0.0º - - - - - - - 3.00” - - - - - - 0.0º
1600 - - - - - 12.0° - - - - - - 7.50” - - - - - - 20.0º
2400 - - - - - 16.0º
4600 - - - - - 22.0º

[Goats86]

Don't run carbs or sbc's but enjoying your writeup. Thanks

[Gregski]

Originally Posted by Goats86

Don't run carbs or sbc's but enjoying your writeup. Thanks

thank you for the kind words, I hope to keep your interest

[Gregski]

well gentlemen I have thrown a bunch of numbers at you and that's all fine and dandy but it all don't mean nothin' if the truck don't run good and don't drive good, am I right?

so how is the driveability?

well it's good, actually it's very good, the best way I can describe it as I get closer to the 14.7 magical number AFR for my idle circuit is that the truck feels LIGHTER, it no longer feels like I am pulling a 2 ton truck ie 4,000 lbs it feels like a hot rod, for real

the Goal being:

Idle = 14.x AFR (this is the P.I.A. hard to get still consistently)

Cruise = 15.x AFR (we got this, so that's good) whoa Greg aint that too lean? no everything I read says at part throttle cruise, ie you in truck with one arm around your girlfriend on the bench seat cruisin' at 70 MPH down the highway (praying the wife don't catch you, jk) only takes maybe 30 HP to move that truck so lean aint dangerous cause they aint a huge load on our rigs, read up on it fellers it's facinating stuff

but we are not out of the woods just yet, I am learning that this 4160 carburetor although a very good carb, (for 93% of us daily drivers, not 92% not 94%, ha ha but 93%) is NOT very tuneable

say what?

allow me to explain, it would be better if I could tune two other things, one being the idle air bleeds (tiny vertical pipes in the main body of the carb) and the second the idle feed restrictions (tiny little tunnels in the metering blocks) again neither adjustable on the 4160 carb (can we say Quick Fuel Technologies... stay tunned)

pics of me trying to get to 14.7 AFR at idle

[Gregski]

well the Manual Steering conversion has been kicking my butt on my truck Restoring Rusty - Manual Steering Conversion but in the meantime I have been acquiring books and reading up on all things Holley carburetor, hee hee

[Gregski]

having read up a bit I have some time to mess with the tunning a bit more tonight, remember the problem is that I still can't lean out the Idle circuit enough to 14.x Air Fuel Ratio which makes my WOT run way too rich at 11.x and 10.x per bank

so tonight I am going back to square one and adjusting what most of us take for granted the Float Levels which effect the air fuel ratio, when you lower them you lean out the mixture when you raise them you richen it up, believe it or not the carb is gravity fed, so the more fuel in the bowl the heavier it is so it pushes harder out the main jets into the wells, less fuel in the bowl the lighter it is so it pushes less

my truck started out at 13.x AFR this evening after driving it home from work and being totally warmed up, after I adjusted both float levels (primary and secondary by half a turn clockwise) I leaned out the ratio to 16.x that's too much but then I richened it up by turning out the idle mixture screws which gave me a happy 14.x

TDT - Test Drive Time to see what that did to WOT Wide Open Throttle from 2000 RPM to infinity and beyond

[Gregski]

man this 4160 budget economy OEM style Holley carburetor is killing me I just can't get it to idle at 14.x Air Fuel Ratio

I have now nearly bottomed out the fuel floats by going one whole turn clockwise from bottom of site hole

I even replaced the 65 main jets for the smallest ones in the Holley tuning carburetor kit which were 64s and still the best it does is idle at 13.x

I know what is in need of adjusting the idle air bleeds or the idle restrictors neither of which are tunable on this carb without drilling things, and I don't want to do that

so next month after pay day I am converting this thing to a 4150 carb, I may even get the center hung float bowls that have the sight glass in them because this pull the plug out and watch fuel drizzle out when you bump the truck with your hips may have been cool in 1969 but it aint no longer

[SkinnyG]

Does it idle best at 14.x:1? Or is that just your target?

I usually set idle mixture as lean as I can yet keep the engine happy and stable. It's not always 14.7, it's usually richer, like into the 13's. But - not all engines are equal.

Idle mixture ~shouldn't~ affect WOT, since idle ports and transition ports/slots require vacuum to work, and WOT should have zero vacuum - all venturi, baby, yeah! Float level will affect everything.

[Gregski]

Originally Posted by SkinnyG

Does it idle best at 14.x:1? Or is that just your target?

It is just a target / goal.

Originally Posted by SkinnyG

I usually set idle mixture as lean as I can yet keep the engine happy and stable. It's not always 14.7, it's usually richer, like into the 13's. But - not all engines are equal.

I understand how time of day can even effect a carb so that optimal settings are just hypothetical, but I still want a carb to be able to reach that ratio even if most of the time I am happy like you with a 13.x

Originally Posted by SkinnyG

Idle mixture ~shouldn't~ affect WOT, since idle ports and transition ports/slots require vacuum to work, and WOT should have zero vacuum - all venturi, baby, yeah!

I hear you, however please check out Gerards Bob2000 webpage at Carburetor Tuning the Scientific Way I think the guy has been there and done that plus he is an engineer from Cal Poly, so all in all smart dude. He reiterates what I have read in other places that the circuits build on top of each other, Idle + Transfer + Main + Power Valve

I have included a diagram from his site below

Originally Posted by SkinnyG

Float level will affect everything.

thank you for your comments I am a newb at this and not trying to hide it, every bit of information helps as I am learning

[MF Doom]

I know if you tune a ls motor it runs a hell of a lot better and stronger than factory. not sure if these are relatable in anyway but just throwing it out there. What's the main benefit of tuning in a carb this much? HP gains? sorry if you already explained the purpose of this lol read 70% of it tbh

[Gregski]

Originally Posted by MF Doom

I know if you tune a ls motor it runs a hell of a lot better and stronger than factory. not sure if these are relatable in anyway but just throwing it out there. What's the main benefit of tuning in a carb this much? HP gains? sorry if you already explained the purpose of this lol read 70% of it tbh

actually this is not tuning it much at all, I am just going very slowly and documenting everything even my mistakes and struggles, once you know what you are doing and assuming you have a fully tunable carb (which mine is not, non of the Holley street carburators are, Demons are more tunable and Quick Fuel are fully tunable) you can be done in an hour

there are benefits to tuning both types of engines, carburated and fuel injected ie throttle bodied, the fuel delivery system does not matter

the newer engines such as the LS are able to run leaner I think (at cruise 17 maybe 18 AFR) but I know nothing about them (yet) so that's why I focused on what I had and began with a carb motor, if I did an LS swap on this truck I would be doing the same thing to tune it, plus these types of DIY diagnostic tools did not exist in the 70s and 80s unlike the LS motors that come with ODBII computers and Oxygen Sensors from the factory.

in my case I have a scenario where I bought an "aftermarket" Holley carburetor, (like most or many Hot Roddres go out and do) in all fairness a very good one but as most manufacturers do, it is pretty much designed to do all things to all cars, ie run on as many different cars as possible, which equals more sales (I am not a synic here just saying) so Holley tunes it to do so

also Holley don't want some dude to run it too lean and blow up his engines than go on some forum and complain about a bad Holley carb, so out of the box they come out a bit on the rich side to keep the engine from overheating and bad things happening

for a carb small block chevy I like heuristics ie rules of thumb, and over the last few months maybe years I read enough to sort of have these fuel ratio guidelines (have I tested them on a dyno yet, no, but its coming up very soon)

Idle should run at 14.x AFR Air Fuel Ratio (13 is acceptable)

Cruise should run at 15.x AFR Air Fuel Ratio (16 is acceptable)

Power should run at 13 (not 13.5) Air Fuel Ratio (though my old dyno guy said SBCs generate the most power at 11.5) well we shall see

I hope I am answering your question.

So who am I who do I think I am?

I am just a guy who likes to get his hands dirty but not fly by the seat of his pants, ie I don't believe you tune an engine by saying yup that sounds about right, or by putting your hand against the exhaust pipe and going oh yeah that feels right. COME ON MAN, have guys tuned their trucks like that for decades, yes sure absolutely, does that mean they were tuned properly, I strongly doubt it as there are some such subtle differences in the air fuel ratios that you can make that they do not change the RPMs where the human ear can pick the differences up nor the exhaust pulse yet the ratio can change by as much as a point

Yes AFR gauges are still very expensive but they are invaluable,

• not only for fuel efficiency

• but health of your engine (I may have discovered that the passenger side bank on my engine runs richer than the driver side - is one spark plug fouled up and missfiring, is there some other issue?) I would not find this other wise

• And Yes finally for power, but I say finally not firstly as it is super important to have everything else in order first, a lot of youngsters [ahem] and oldesters, ha ha, skip the idle circuit and head right for the power valves right for the squirter ie accelerator pump - hewk I know of many cases where going smaller jets and smaller fuel pump nozzle improved the performance of the vehicle not the other way around

[MF Doom]

Originally Posted by Gregski

I am just a guy who likes to get his hands dirty but not fly by the seat of his pants, ie I don't believe you tune an engine by saying yup that sounds about right, or by putting your hand against the exhaust pipe and going oh yeah that feels right. COME ON MAN, have guys tuned their trucks like that for decades, yes sure absolutely, does that mean they were tuned properly, I strongly doubt it as there are some such subtle differences in the air fuel ratios that you can make that they do not change the RPMs where the human ear can pick the differences up nor the exhaust pulse yet the ratio can change by as much as a point[/LIST]

wow, very detailed response! thanks. bookmarked for future references. This part makes me feel somewhat better i guess lol i tried to dial in my carb/motor the "right" way with the vacuum gauge and a timing light. It still runs like crap but better than nothing right?