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

[KQQL IT]

Had a similar hesitation 950 hp double pump, but primary side is a near cousin.
Mine wanted a bigger cam, orange maybe. Tried a black cam. Too much would like to flood with 2-3 pumps

[Gregski]

Originally Posted by KQQL IT

Had a similar hesitation 950 hp double pump, but primary side is a near cousin.
Mine wanted a bigger cam, orange maybe. Tried a black cam. Too much would like to flood with 2-3 pumps

interesting, that's a huge carb, what's it on?

[KQQL IT]

Originally Posted by Gregski

interesting, that's a huge carb, what's it on?

It's only 850 cfm for real, but my drag race 406 sbc.

[SCOTI]

Originally Posted by Gregski

Alright this left us with a slight hesitation upon blimping it, aka flooring it while in neutral, it would go

vrooo vroooooom, instead of a smooth vrooooooooooooooooooooooom

so it was time to try a bigger accelerator pump nozzle or a different accelerator pump cam, I bought both just in case

my carb came with the .031" and the next size up is the .032" which I thought would not be enough so I bumped it to the next size up the .035"

let me tell you swapping the little nozzle is a major PIA, I had to take the carb off to do i, as those pesky little black washers kept falling on the butterflies, danger danger

the bigger squirter took care of the hesitation while flooring it in neutral and the truck is running BEAUTIFULY!

Any updates? Still running good?

[Gregski]

Originally Posted by SCOTI

Any updates? Still running good?

Man, I had a Dyno Test scheduled for a Tuesday and so on Saturday the weekend prior I decided to check the fluids and spark plugs, and things took a turn for the worst, I found the #5 spark plug all fouled up [again] with major carbon deposits...

so I did what any frustrated Hot Rodder would do I tore the engine all apart to investigate, you can follow along here on my build called Restoring Rusty ...

[Gregski]

well with the engine all back together, new rings, new con rod bearings, it's time to start tuning all over again

no worries it is a great way to firm up our tuning skills

so we start with the distributor, and please if you have not read anything about setting ignition timing, read the following two articles by John Hinckley or if you read everything about timing and are more confused than a blind goat on astroturf again please give these two easy reads a go

Timing And Vacuum Advance 101

MAPPING YOUR ADVANCE CURVE

Spoiler Alert - my two take aways were:

1. you need more advance at idle/cruise than at wide open throttle

2. manifold vacuum is better than ported vacuum for the vacuum advance canister

[evan]

Thanks for posting all that. I hope you're able to get such a good result again after the rebuild.

[57NAPCO]

Now that! was a most impressive read.

Thanks for taking us down that road, that was a lot of work. After reading this I just might try and tackle some tuning on one (or more) of the trucks I have. This is something I never would of considered doing prior to reading your thread...and I've been messin with these trucks for 40 years, not as a real mechanic, but a jackleg mechanic


*Jackleg
~ lacking skill or training : amateur <a jackleg carpenter>
~ designed as a temporary expedient : makeshift

[Gregski]

Originally Posted by evan

Thanks for posting all that. I hope you're able to get such a good result again after the rebuild.

You're welcome, I appreciate the feedback.

So to be honest with you I am still to get the carb dialed in after the new piston rings went on. It's about 80% there. Not to make any excuses but I swear the temperature has dropped 40° since last time I toyed with it. Seems like we went from Summer to Winter with only about 2 weeks of Fall, ha ha

So we are reminded of the three evil sisters when it comes to performance, Temperature, Humidity, and Elevation.

Now I am in Sacramento, CA so at least Elevation stays the same for the most part, I think we are at sea level or about 9 feet above.

I already mentioned that temperatures went from 80° F the last time I tuned the carb to 40° F and that is a huge change (cold weather packs in more air, the molecules are closer together or something like that) so your truck tends to run leaner in the winter if you don't give it a little attitude adjustment (think idle mix screws and turn them counter clockwise a quarter turn or so)

Well the humidy don't help either, and it don't have to be raining to be at 100% humidity, that don't help either that makes the truck run richer as there is water in the air and therefor less air enters the carb, since each air molecule has a water buddy hanging out with it type a thing.

but stay tuned, (pun intended) I am about to go Def Con 4 on this ol' Holley!

So the only problem is when I start rolling in first gear and accelerate to go into second, the carb leans out to say 20 AFR(ish) way too lean

It could be one of many things, but I am thinking the vacuum secondaries are opening up too soon now and I need to go to a harder / tougher spring

[Gregski]

if you get in the Holley carb tuning game you might also have a full drawer that looks like this, ha ha

[Gregski]

so just a quick update, I replaced the vacuum secondary spring with a stiffer Purple one to delay when the secondary butterflies open, and took the truck for a test drive, and it accelerated much better, so I will drive it to work for a week and report back on how it performs

[Gregski]

I also noticed that I was idling really rich at 11/10 AFR (left and right banks) can you tell why, here's a hint

HUMIDITY:

When I started the test drive it was at 99% by the time I finished and took the pic of the weather on my phone it said 90%, still incredibly high

[LT7A]

Hey Greg, what a great compilation of information! To be honest with you, when you mentioned the AFR gauge in your other thread, I thought, ok, but it seems kinda gimmicky to me. Man I was wrong. Really cool how you were able to dial out the hesitations and significantly improve your gas mileage. I look forward to learning how to set up a portable system that I can move from vehicle to vehicle. Keep on it man, this is cool.

[Gregski]

Originally Posted by LT7A

Hey Greg, what a great compilation of information! To be honest with you, when you mentioned the AFR gauge in your other thread, I thought, ok, but it seems kinda gimmicky to me. Man I was wrong. Really cool how you were able to dial out the hesitations and significantly improve your gas mileage. I look forward to learning how to set up a portable system that I can move from vehicle to vehicle. Keep on it man, this is cool.

thank you so much for the kind words

[Gregski]

Well its been a while since I updated and with the Holiday season behind us its time to get back into it. Today I replaced my 6.5 Power Valve with a 10.5 one. I believe that is the biggest one. Why did I do that? Well I noticed that I get incredibly high vacuum at part throttle, 19 to 20 inches of mercury I guess its called not PSI for vacuum. So as I am cruising around at part throttle say at 45 MPH I am pulling that much vacuum. The problem being when I give it gas my engine leans out to like 20 AFR way too lean and the car stumbles until it catches up on fuel

Now don't get me wrong vacuum is good, vacuum is the central nervous system of pre Electronic Fuel Injection (EFI) cars, however the Power Valve needs to be tuned accordingly.

So what the heck is a Power Valve and what does it do?

Well I heard it called an economy valve and I tend to buy into that nomenclature. The Power Valve is a spring loaded diaphragm helper a little assistant (see earlier Post #125). As you are cruising around at part throttle the car is not under very much load, its pretty easy to roll the car around once its rolling, somewhere I read it only takes like 25 horse power. You ever push a heavy something and once it started rolling you could just keep pushing it with one hand. Well same idea here.

Anyway there you are cruising around and all of a sudden you give it more gas to speed up for what ever reason, maybe you are on a freeway onramp and need to merge into traffic. What happens in the carb? Well the butterflies fling open and a ton of air rushes into the carb. But wait what about the gasoline? Well air moves much faster than gas, so your carb goes lean, way lean until the gasoline catches up.

So its the Power Valves job to flow more gas and what tells it to do so is vacuum, more precisely a drop in vacuum. The numbers on the Power Valve tell at what vacuum the power valve will open. So as my vacuum drops from 20 to 19 to 18... I had to wait until it dropped to 6.5 before my old Power Valve would let more gasoline into the intake manifold. Now I only have to wait until the vacuum drops to 10.5

I think the reason that the Power Valve is dubbed the economy valve is that its like a gatekeeper it prevents too much gas flowing through when you don't need it (cruising) and more to flow through when you accelerate but based on the vacuum signal and not your right foot.

The Accelerator pump reacts to your foot if you mash the pedal it will squirt, if you gently press your gas pedal slowly down to the floor the accelerator pump may not even squirt at all, yet when the vacuum drops beyond a certain level 6.5 or 10.5 that Power Valve is opening.

hope that makes some sense, please correct me if I am wrong

[SkinnyG]

I've never heard it called an economy valve, but your understanding of how it works is reasonable.

One of the ways I describe it all is this:

You want a good, perfect idle, so you make the idle fuel ports adjustable with mixture screws so you can make it perfect.

You want good full throttle power, so you make the main jets big enough to feed the engine for full power.

Except that will be too much fuel for good economy when cruising, so we create a valve that can restrict most of that fuel for when you're cruising. On your Holley, it's a Power Valve. On a Q-Jet, it's the metering rods and power piston spring.
---
Curious - what is your idle vacuum reading? It is often recommended to have the power valve open at half your idle vacuum reading.

[Gregski]

Originally Posted by SkinnyG

...You want good full throttle power, so you make the main jets big enough to feed the engine for full power.

Except that will be too much fuel for good economy when cruising, so we create a valve that can restrict most of that fuel for when you're cruising. On your Holley, it's a Power Valve. On a Q-Jet, it's the metering rods and power piston spring.

I just want to point out that the Power Valve does not "restrict most of that fuel" which when I read your comment implies coming from the main jets. Not trying to argue or say you are right or wrong I am just stating that the Power Valve is an additional circuit or an additional way to get fuel from the float bowl to the main well. The jets give the fuel two paths from the float bowl to the main well. And between those two jets sits the Power Valve and it provides actually two more little holes called PVCRs Power Valve Channel Restrictions which are opened and closed using a single Power Valve. So yes in the end the Power Valve controls how much fuel enters the main well but through its own additional path and not the Main Jets, just thought it was important to clerify that (since it took me a while to learn this so now I must show off what I know, JK, ha ha) again I think we are both trying to say the same thing so I appreciate your comment (as always)

[Gregski]

Originally Posted by SkinnyG

Curious - what is your idle vacuum reading? It is often recommended to have the power valve open at half your idle vacuum reading.

Great question, and I have seen that formula as well, my highest steady vacuum at idle of 900 RPM is 20 inches, yes that high, so the 10.5 Power Valve makes sense, I think maybe I could use or try the 9.5 but they were sold out of that one.

[Gregski]

Originally Posted by SkinnyG

I've never heard it called an economy valve, but your understanding of how it works is reasonable.

I think technically they called it the "economizer" valve, I tried Googling it and yup Power Valves show up.

Dave Emanuel mentions it in his Super Tuning and Modifying HOLLEY Carburetors book, great read, he is a funny guy and explains things wonderfully, highly recommend one of his books

[Jay2Cor517]

Originally Posted by Gregski

P/N: 3851, MSRP $169 I scored it for $130 new and free shipping on eBay

one gotcha is that this gauge did not come with the "intermediate" Molex cable to connect it to the existing gauge / controller so I will have to purchase that separate now I can use it in stand alone mode, but the whole point of going with all gauges from the same company is that they integrate and plug in to each other, very cool stuff

I had been looking in to tuning using an AFR gauge for a while now and you have convinced me it's worth the effort. The plan is to order the dual AFR gauge and vacuum/boost gauge then install at the same time. As far as the 'gotcha', what is the P/N for the cable? I went to their website but couldn't figure out which one. Thanks for all the hard work, documentation, pics, graphs, trial and error etc. It's makes it just that much easier for the rest of us to follow. Keep posting--Jay2Cor517

[Gregski]

its been a while since I updated, if you follow my Restoring Rusty thread you may be aware that we had to move again, I swear if you want to sell your house let us rent it from you, it will sell ASAP, ha ha

anyway finally got the center hung float bowls with proper sight glasses on the carb and a proper dual inlet fuel line setup, can't wait to tune it now

mounted it on with a 1" four hole plastic spacer and had to use 2 1/2" studs cause the 2" I had were still too short

the spacer is a good idea and some would say the taller the better, and if you got the space like we do in these trucks under the hood, why not try it, it keeps the heat off the intake manifold away from the carb and gives the air/fuel mixture a longer path to mingle properly on its way down

[LT7A]

Had me laughing here:

I swear if you want to sell your house let us rent it from you, it will sell ASAP

Glad to hear that you are also a Jeff Smith fan. Thanks again for writing all of this up. I used to think that this kinda stuff was beyond me technically. Now I enjoy it because of how effective I learned that it is, due to this thread. And it makes my mental matter hum.

[Gregski]

Originally Posted by LT7A

Had me laughing here:



Glad to hear that you are also a Jeff Smith fan. Thanks again for writing all of this up. I used to think that this kinda stuff was beyond me technically. Now I enjoy it because of how effective I learned that it is, due to this thread. And it makes my mental matter hum.

makes for great conversation and takes the pick up line to a whole new level: "hey baby I can make your engine run at a perfect stoic 14.7 AFR all day long!" jk

[SkinnyG]

Actual question I put on a printed Fuel System Quiz:

14) Spell "Stoichiometric"
a. Stoechiometric
b. Stoikiometric
c. Stoicheometric
d. Stoichiometric

Nobody got it right.

[Gregski]

Originally Posted by SkinnyG

Actual question I put on a printed Fuel System Quiz:

14) Spell "Stoichiometric"
a. Stoechiometric
b. Stoikiometric
c. Stoicheometric
d. Stoichiometric

Nobody got it right.

that is hillarious!