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Discussion Starter #1
Recently, I bought a Quick Fuel 680 HR vacuum secondary carburetor, and being a Quick Fuel, it is almost fully tunable. Yeah, 680 might be a bit big, but I like to rev high, and some extra tuning can get things to work well down low. I have used both an Edelbrock 1406 and a Holley 570 Street Avenger, but I wanted more. I wanted the fuel economy of the Edelbrock, and the power and easy starts of the Holley. I've also recently been reading David Vizard's How to Super Tune and Modify Holley Carburetors, and it would appear that both are achievable with the right tune. The Eddie and the Street Avenger just didn't have the tuning capabilities to get there on their own.

From the factory, the QF comes tuned pretty rich across the board, with 70 main jets and 74 secondary jets. I brought it down to about 66 on the mains and 68 on the secondaries before even installing it. Ran great that way, though it was pretty rich cruising down the highway. Additionally, there was a bit of a flat spot as I rolled into the throttle. I figured it was from too much of an accelerator pump shot, so I dialed back from a .031 squirter to a .028, which seemed to help the pump shot last longer (more testing is needed to find out if that's the case). Dropping to a 64 main jet made it surge at cruise, so I went up to a 65. It was better, but still surged slightly. Back up to a 66.

The last full tank I did on that tune showed 13 mpg with mixed city and highway driving. So, I tried the old "Wire strand in the idle feed restrictor" trick, but that leaned it out too much. Turns out that's a crude way to lean out the idle mixture. Time to get serious. Bought a pack of blank restrictors, a pin vise, and #61-80 wire size drills. The QF came with .031" idle feed restrictors, so I started out two sizes smaller, at .028". That proved a tad too small, so I went up another size to .029, and that seemed to do the trick. I also advanced the ignition timing (though my timing light went missing, so I don't know how much), but that raised the idle speed too much so that the throttle blades are basically closed, and the transfer slot is totally covered. And there's a bit of pinging at part throttle now.

The idle restrictor tuning was done last night, so today I'll back off the ignition timing and try to get the idle speed and throttle opening to a more ideal point. I have not yet touched the air bleeds, since I'm still trying to get a feel for getting the base jetting. But the idle air bleeds are 70s, while the main circuit air bleeds are 28s. I have a vacuum gauge in the dash, but I didn't hook up the backlight because it's temporary; and I have plans to get an air/fuel ratio meter to fine tune the mixture, but that's around $180 for a decent one. Soon, though.
 

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Discussion Starter #2
Also, I have a full MSD ignition with a Pro-Billet distributor, Blaster II coil, and Digital 6AL box, so I'm thinking I'll open up the plug gap a bit to help on the fuel economy front. I'm running an .035 plug gap right now, but I could probably run much more than that.

I really do think that I can get mileage similar to the Edelbrock. With it, I have gotten up to 25 mpg cruising at 55-60. Both the Eddie and the Quick Fuel have dog-leg boosters, and the Quick Fuel is much more tunable, so I should be able to get similar results.
 

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My experience is with Autolites but I have found that it impossible to know what you are actually doing without AFR meter data. A great deal of what I had read about carbs turned out to not agree with reality. Once I plotted the actual data it became obvious what should be done. I am pretty sure the Holleys are similar although with more potential adjustments. Idle, transition and cruise are distinct operating modes and the adjustments for one have little to do with the others. Only above 50 MPH do the main jets in an Autolite do anything, etc.

Your highway MPG at 60MPH+ is almost entirely determined by main jets and how well balanced the air bleeds are that go with them. A well adjusted Autolite will hold a constant AFR from 55 to 80+ MPH.
 

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Discussion Starter #4
My experience is with Autolites but I have found that it impossible to know what you are actually doing without AFR meter data. A great deal of what I had read about carbs turned out to not agree with reality. Once I plotted the actual data it became obvious what should be done. I am pretty sure the Holleys are similar although with more potential adjustments. Idle, transition and cruise are distinct operating modes and the adjustments for one have little to do with the others. Only above 50 MPH do the main jets in an Autolite do anything, etc.

Your highway MPG at 60MPH+ is almost entirely determined by main jets and how well balanced the air bleeds are that go with them. A well adjusted Autolite will hold a constant AFR from 55 to 80+ MPH.
Definitely agree with you on the need for an AFR meter. I really want to get that and the vacuum gauge mounted to the steering column, then film those along with the tach and speedo for my data-logging. That way, I can also get some audio to determine misfires or pinging. I really want to be able to see when the main jets kick in on the Holley so I can figure out what to tune and why. Otherwise, I just know I'll be chasing my tail.

Another trick I learned from reading Vizard's book is to take a vacuum hand pump, hook it up to the distributor's vacuum advance, and use that to find the optimal ignition timing for a given speed. Might be worth a shot at some point.
 

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HI Paul, I have done a lot of holley, quickfuel tuning on my 302. I've found that with a bit of fine tuning the bigger carb works well especially with a dual plane intake. When I had a 650 holley I was using 70 main jets and a 50 thou PVCR. I highly recommend getting a wideband, mine is an innovate that can data log, you can also add a vacuum gauge, RPM and log those too. Cheers Clint
 

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Discussion Starter #6
Thanks, Clint! I've been looking at the Innovate stuff, but it looks really pricey. I know there's no substitute for having information, but I just don't have the funds to splurge on datalogging. I'll definitely be getting a wideband O2 sensor, though.

Drove to work today, after bumping the timing back and going from .070 to .069 idle air bleeds. There was almost no throttle response under about 1/4 throttle or under 1700 rpm, so I think I need to go back up to the .031 IFR. Maybe add a bit more IAB, or add main air bleed. The 66 main jets still feel spot on, though.
 

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I resisted for years also thinking that a wideband meter was a lot of money. However, once I finally bought one I don't know why I waited so long. Its the difference between night and day, guessing and actually knowing what is happening. I considered the Innovate to do data logging but the more I read I became concerned about reliability and accuracy. The 'meter' is actually a computer with quite complex software that you never see but the algorithms are important for calibration and accuracy. I decided on the NGK version which supposedly is fairly close to the multi-thousand-dollar systems used by the auto makers. I have no regrets and have had it mounted continuously since delivery on one of 3 different cars in the last 3 1/2 years. No cabling or grounding problems and it always works as expected.

Until I owned one I didn't realize how useless the digital display would be. The 4-digit display looks 'accurate' but instead its a nuisance of randomly displayed digits that often mean almost nothing. You need to either log the data or have an analog display which is much easier for your eye/mind to interpret. I adapted a 3" analog meter with a 270 degree sweep needle to the standard 5V output from the AFX meter so I can monitor and interpret what is happening as I drive. No need to wait until I can plot the logged data, its obvious from the analog display as I am driving. After using that for a few weeks I decided that data logging wasn't as important as I had originally thought. Logging would be useful for transient events but the main use for the meter is to get the basic carb set up so it runs correctly in steady state at any speed. Once you know that is correct then transient problems are mostly gone and the remaining ones are pretty easy to fix.

Unfortunately, the original NGK AFX has been replaced by the AFRM. For a variety of reasons I preferred the original AFX which for a while was sold by Ballenger with their own AFR500 part number. It was obvious that NGK was supplying their old style meter to Ballenger after NGK stopped selling them. I see now that both have been 'upgraded' and are now 'Version 2' or 'Gen 2' along with price hikes to over $300. I am not sure what I would buy today.

The supposed 'upgrades' to the NGK were mostly to widen the AFR ratio. The original was 9-16 which is about all you really need. The AFRM displays from 9-20 which sounds better but it reduces the resolution where you really need it in exchange for extending the scale to 20 which you can't use unless you have a computer controlled engine from the last few years. Then to make it worse, the V2 ones now are 6-20 which extends the scale into more unusable territory on the rich side. Your 289 won't run below 9 or above 17 so most of the added capability is meaningless to those of us with carbureted engines. The ideal AFR scale span for our engines would be 9-18.
 

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Discussion Starter #8
Ended up buying an analog-style AutoMeter AFR gauge. I'll probably be able to install it sometime next week. Hopefully I don't need to remove a header to do it. I probably will, though.

As for the current lean running, I'll compensate for it by enriching the idle screws for the trip home. I'll fix it properly later, and go a size bigger than stock. From there, I might tune with air bleeds.
 

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paul289,
Innovate is cheap junk made in China. they have a huge warranty problem. some may be happy with it but I'm not.
 

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Innovate is cheap junk made in China. they have a huge warranty problem. some may be happy with it but I'm not.
That was the concern I gathered from reading problems others were having with them.

If its the AutoMeter version with the 8-18 range then you will never have a problem with off-scale readings. Otherwise, I have no experience with AutoMeter products.
 

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Discussion Starter #11
Almost all of my gauges are Autometer, so I figured I'd stay with the brand. The only exception being an Equus vacuum gauge because that's what O'Reilley's had.

I've gone two sizes up on the idle feed restriction to .032, so we'll see how that does. But I can't test that out until I fix my Z-bar. The pedal arm has developed a nasty crack that's gonna need to be welded up and reinforced again. Awesome. Hopefully I can get that done tonight.
 

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Discussion Starter #12
Went for a long drive on Saturday, and it was still running a bit lean. Went up one more size to .033 IFRs and that seemed to do the trick! It's cruising really well now, no surging or anything! So, over 125 miles on the .032s and another 25 on the .033s cruising at 50-65 most of the time, I got 19 mpg. I think the .033s could get better than that, since the surging misfires just dump fuel into the exhaust.

I also have an AFR meter now. Just need to hook it up. This isn't going to be very fun, though. I don't want to pull a header if I don't have to.
 

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I've had several AFR wideband a/f meters on different cars. Never any issues with them. I first bought the digital version, but never warmed up to the modern display. I switched to their analog version several years ago for my Weber equipped K code. They worked great

I may have missed it, but I don't see where the OP has tried to lower the float level. I've installed many Holley carbs on customer cars as well as my own cars. Every one of them needed to have the float level lowered. This cannot be emphasized enough: lowering the float level will help with a rich condition across the entire powerband. The float level can be lowered dramatically without any danger of fuel starvation.

The two easiest tuning changes that will improve nearly every vintage Ford are running more ignition advance and loweringthe float level on cars that have Holley carbs installed.


( Normal Rich idle reading on Webers )

Z
 

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Discussion Starter #14
Currently, I'm suffering from a lean condition, though it has gotten better. I have thought about changing the float level (raising, in my case), but I'd like to try to get the jetting right, first. I'm thinking I'd use the float level adjustment to fine-tune for atmospheric changes, such as high altitude or changing temperatures.
 

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".......... But I can't test that out until I fix my Z-bar. The pedal arm has developed a nasty crack that's gonna need to be welded up and reinforced again. Awesome. Hopefully I can get that done tonight.
Here are two photos of a reinforced Z bar that I've used for many years. Not the best visibility, but you can see where a triangle reinforcement was added, and also a bar was welded to both arms their entire length to add more stiffness.

The original Ford Z bars were bending from day one. It's not uncommon to find them being used today with varying degrees of bend. Cracking is more rare, usually they just fold over.

Z




 

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Discussion Starter #16
The cracking was most likely because I had previously reinforced it because of bending. I had used a piece of angle iron as seen in a previous thread here: http://www.allfordmustangs.com/foru...445744680-clutch-binding-bends-z-bar-15-2.jpg
I welded another piece onto the passenger side of the pedal arm and welded up the crack, so hopefully that'll last long enough to allow me to install a hydraulic clutch in a month or so.
 

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Nice vise, and oil can !

PS. Yeah, if you strengthen the arms it becomes very important to weld a triangular piece of metal from the tube to the arm(s).

Z
 

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Discussion Starter #18
AFR gauge is hooked up and working! Helped dial in the idle mixture, which was jumping between 15 and 17 or so. Got both sides working right, with idle AFR mostly stable around 15. Still, feels like there's a misfire somewhere since my eyes were stinging from the fumes. I'll check the spark plugs to see if one doesn't look great. But the plug gaps are all around .050". I think there's probably an exhaust leak at the header collector, too. It's bounced off of speed bumps a few times and is pretty beat up.

But now I need to replace the brake light switch, which is stuck on. And one of the bulbs burned out. Always something, I tell ya.
 

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Plug gaps of 0.050" is a little too wide in my opinion. You aren't gaining anything by going over 0.040"

Z

ps. exhaust leaks upstream of the O2 sensor will affect the gauge reading.
 

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Discussion Starter #20
MSD recommends plug gaps of .050-.060" with their full ignition. I've got the Digital 6AL box, Pro Billet distributor, and a Blaster II coil. Wider plug gaps allow more spark energy to ignite leaner mixtures. The gain might not be a whole lot, but if I can do it easily and it doesn't hurt, why not?

I think the header is sealing just fine at the cylinder head, but there could be some reversion from a leaky collector seal. I really just need to redo the whole exhaust.
 
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