FiTech Dual Quad

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matthon

matthon

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I don't see much if anything on-line on the dual quad efi, let alone on a tunnel ram, so I thought I'd put this out there and see what happens. Of course, I can add to it when I learn something new, if there is interest. I also have a question on my spark plugs at the bottom.

383, aluminum heads, tunnel ram, efi.
I went from the tunnel ram with Holley 390s, to 600s, to a Performer RPM and a 750. I honestly preferred the way it ran with the tunnel ram.

I got the FiTech 30064, the Tanksinc tank, and passed on their pump, bought the FiTech pump, cut a 4 inch hole in the tank, capped the regulator, done. AN fittings right on it, o-ring gasket if it ever needs to come out. Put the Corvette fuel filter/regulator on the frame, and one teflon braided fuel line up to the engine.

Skip ahead to today, and I've been driving it regularly for a few months.

I increased the Crank Fuel setting for cold starts, it didn't get much better, so I increased the CRANK IAC, with little improvement. Turn the key on, wait for the pump to stop and the throttle body to click, it starts immediately by barely flicking the key when warm, and I mean barely, hold it longer than a second and it won't start as well. Cold starts require holding the pedal down slightly and it fires quickly. I'm thinking this is due to the tunnel ram. I tried turning the key on, off, on, a few times as it's supposed to shoot a small amount of fuel each time, kind of increasing the cranking fuel manually, but that did not help. I'll increase the Crank Fuel setting again and see what happens.

I installed a new throttle cable and made my own in-line linkage because for some reason a quality piece doesn't exist in the aftermarket. This helped immensely with finally getting the IAC set, which is now set perfectly and has remained stable since. The old linkage actually tweaked the one throttle body arm and put it out of alignment with the other.

I have been gradually increasing the Accel Pump and Fast Accel settings and the DFCO Return Fuel setting to get the AFR set.

Last week I adjusted again adding more fuel and it has responded well, best yet. I will probably increase again in a week or so, and back off if needed.

In the beginning I was misinterpreting what was happening when running through the gears, I thought it was dying on me too soon, then I realized it was getting up to speed faster than before and I needed to shift sooner.

The amount of air this thing is pulling in has increased greatly. You can hear the air rushing into it, in the exhaust, which is newer, I can now hear the slight leaks where the pipes are joined, to the point where I want to get it welded up. I have a scoop that I put on sometimes on top of the air cleaners and the AFR goes up.

Pulled the plugs today, just curious, but I'm not sure where they fall in the many online resources. They've been through a number of adjustments, so maybe I need to start with a fresh set.

Another thing, I put the highest octane in a few days ago, I have always used the lowest, it didn't run any better, in fact the only difference was it started to smell more like exhaust, not rich or gas, just exhaust. I finally filled it up today with the regular and it's back to normal.

Any thoughts on anything would be appreciated.
The plugs are RC12YC.

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If those are the plugs that came out of it, that fuel distribution could use some work.
I like that concept though!
 
Changing the fuel's octane ratings does nothing for power if you don't tune for it.
Higher octane fuel is usually not 'better'. It just has a slower burnrate to prevent pinging. But the slower burnrate means you can now further optimize/advance your ignition timing, and that as such could make more power.

If installing the scoop raises the AFR number this means the scoop is leaning out the carbs. Most likely because of cooler airflow.
Denser air versus same amount of fuel = leaner.

Things get even more fun if you start digitally controlling the ignition timing as well.

Can you tune the individual injectors on this system?

Side note
I wouldn't run Champion plugs even if they paid me money for it.
 
Fuel distribution, I wonder if it is possible to modify that with the efi and tunnel ram.
Probably relates to tuning the individual injectors, which I don't believe is possible, but I will research.

Are the runners for each carb on a low dual quad intake separated from each other?

The tunnel ram has an area below the carbs where the air/fuel from each throttle body can mix, but I think it is needed with the tr. I wouldn't know how to block it off to see if it made a difference.

Good info on the octane, thank you.

Yes, the scoop is leaning it out, but since the air cleaners are above the hood I was thinking the scoop is adding more air, not necessarily cooler. The scoop is on top of the existing air cleaners.

I like to use the kiss principle, and I keep thinking about the Hot Rod air cleaner shootout, where the tall air cleaner with a solid top was one of the best. With the larger ports in the throttle bodies, the tr, and a need for better fuel distribution, I want to try 2 tall air cleaners too see if there is any truth to such a simple modification making a difference in air flow, or better more direct airflow. I have 1 tall air cleaner, need 1 more.

The FiTech can control the timing, however prior to purchase I bought the ready to run msd because accel discontinued the cap/rotor for the dizzy I had.

I believe the head manufacturer recommends the Champions. They're cheap and easy to change though.
What plugs would you suggest?
 
If the Champions work for you and don't foul whenever a bird takes a **** two blocks down the road, I would leave 'm be.
But I have way more faith in NGK's or Accels.

You need to explain/show how the scoop sits and feeds the carbs on top of those aircleaners. I thought it was just a mockup photo and the scoop would actually enclose the airfilters.
 
LMAO, actually on the ride home today I got the feeling they're fouled now. I'll try the NGKs, I used to run those in an efi turbo car I had and was pleased with them. I believe it will be an improvement.

I built the scoop years ago, it used to just sit on the carbs alone. I took the bottom of the Summut Hilborn-style scoop, modified it a little, modified a newspaper box a little, welded up a small frame from square tubing to fit inside the box. Flat head bolts go through bottom of scoop, box, and frame. Threaded rod goes through the frame with wing nuts, this part of the frame is attached only in the middle, so there is tension on the wing nuts when tightened. Found a k&n air filter that fits a mid 90s gm air box, it was actually in a counter top demo thing and I brought the box in to try it. Trimmed the sides a few millimeters, plastic tabs in the box and two small brackets outside hold it in place. No round filters fit.
One day, I took the tops off the two air cleaners, put in longer rods, and set the scoop on, it slips right inside the air cleaners.

Pics show carbs with just scoop, and efi with air cleaners and scoop.

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That injection on top of an I/R tunnel ram might be interesting. Those throttle bodies have 4 barrels and 4 injectors each? Each injector supply fuel for idle? Set up as individual runners there should be no distribution problems. And much more driveable. But I don't know much about efi....maybe someday.
 
Yes there are 8 injectors and they all supply fuel for idle. Only one throttle body has electronics in it the other is a slave with just injectors. My Dart also has a single throttle body FiTech EFI system in it. This is our first attempts at EFI and turbos and it came out well, dont be afraid to jump in. The EFI only has to have 4 connections to run. Battery, fuel pump, coil negative and ignition on sense, that's it. You will have to get a EFI tank, fuel cell or modify your tank for EFI. You can use an internal pump or get a frame mounted unit like we have on Larry's D150. These EFI systems are "self learning" but believe me you will have to make some adjustments on your own as they are not perfect. It will get you up and running and it will improve as it learns but you will have to fine tune it. My buddy Larry's system is waaayyy overkill for a 318 but he's working on a stroker big block to transfer everything over to, this was more of a '''can we do it?" kind of thing as well as giving him something to drive in the meantime. Because it's a stock bottom end we keep the boost to a Max of 7 PSI. If you have any questions feel free to ask.
 
Hey,thanks for the reply to my post. Oh,I have a lot of questions but only one for now. What's involved in switching fuels say from gas to e-85? Thanks.
 
hangn0ut said:
Hey,thanks for the reply to my post. Oh,I have a lot of questions but only one for now. What's involved in switching fuels say from gas to e-85? Thanks.
Click to expand...
As far as I know the FiTech system is E85 ready and should adjust itself for it. Luckily none of the stations around where I live (Butler PA near Pittsburgh) carrty it. I realize the it's cheaper but you get less performance out of it as well.
 
I have the Accel Pump and Fast Accel settings at 60 for both at 65F and 170F.
The DFCO Return Fuel is at 130.

With the 4 speed, if I ease into it, it will pull great thru 1st, second until about 3200 rpm (then wants to start to stumble), 3rd is fantastic, and 4th I'm either going too fast or contempt.

The AFR will go high and it will stumble if I hit the throttle hard from the get go, or sometimes when grabbing a lower gear to get back into it. The AFR also goes higher at idle.

I increased the DFCO to add more fuel when getting back into the throttle, but it's not completely solved.
I also decreased the Decel open IAC by 10 to reduce the time it takes to return to idle.
I have not touched the AFR Targets.

My understanding is Fast Accel does not mean full throttle, but beyond the initial Accel Pump setting, or roughly more than 50% throttle.

Should I continue to increase these 3 settings, Accel/Fast/DFCO, or are there other settings to consider?

Should the AFR be higher at idle?

For cold starts, should I continue to increase the Crank Fuel, or should I manually open the throttle a little and keep the throttle open/rpms high during warm up?
I've read a tr can foul plugs on cold starts w/o a higher rpm on warm up.

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I think had the same problem you had with cold starts. I used to have to hold the pedal down a little bit to get it to start quicker. I raised my IAC Multi setting by 10 and it solved it. My AF Ratio is 14.2 at idle and I'm at about 13.7 when I am on it at 1/2 pedal and 5800 RPM (cant go full pedal as it breaks the tires loose, I need drag radials).
 
I just gotta say,e-85 probably has the highest horsepower potential of any pump fuel out there. You just need to burn more of it. A lot more. Works great in supercharged motors. It has a great cooling effect on the intake charge. So you can run more boost and/or timing.
Now I have never ran it myself but I do have 30 years experience with methanol. And e-85 is closer to methanol than gas. Just saying don't underestimate that stuff or the cars burning it.
 
superchargeddrt said:
I think had the same problem you had with cold starts. I used to have to hold the pedal down a little bit to get it to start quicker. I raised my IAC Multi setting by 10 and it solved it. My AF Ratio is 14.2 at idle and I'm at about 13.7 when I am on it at 1/2 pedal and 5800 RPM (cant go full pedal as it breaks the tires loose, I need drag radials).
Click to expand...
What are you referring to exactly with the IAC Multi setting?
The CRANK IAC?
 
Hi Matthon,
I looked on Fitech's web site and I found the setting. Its called "Prime IAC Mult" and it's in the "Cranking Fuel" menu. I pasted the description below. If I can help just ask away.

CRANK IAC Mult = The IAC is opened an extra amount during cranking to allow more air into the engine for faster starting, and extra torque to spin the engine against thicker cooler oil. Adjust this to get good starting without excessive overshooting after starting.
 
The only thing close or similar is:
Go-EFI Tuning>CRANK and WARM-UP>CRANK IAC
I've increased in the past, I'll increase again and see what happens.
 
matthon said:
The only thing close or similar is:
Go-EFI Tuning>CRANK and WARM-UP>CRANK IAC
I've increased in the past, I'll increase again and see what happens.
Click to expand...
Hmmm will look at mine (instead of relying on the Fitech website) and I'll see where it's at).
 
Called Fitech yesterday as it doesn't seem to be 100%. After some convincing he decided to help, (tried to tell me everyone is happy with the dual quads with no issues, so I asked how many people call to tell them everything is great!).

BTW he confirmed all the settings for single throttle body are the same for dual quad. Apparently a stupid question, but I reminded him there is nothing anywhere stating either way, you tool.

Told me to check the AFR Trim, s/b -20 or less at idle, around 0 at WOT.
I'm at 50% at idle, which is the max.
Now, you can change the min/max, but not sure that would solve it. Also, AFR Trim effects the AFR Learn, the first being real time, the second a compilation of the Trim data.

So, my thoughts are bad fuel pressure, bad O2, or vacuum leak.

Everything is fairly new, and I'm not sure if this was an issue or not from day 1.

I'll try out the data logging on the way home. I have a fuel pressure gauge, but no AN fitting, and I'm not educated on O2 diagnostic.
My understanding is there is no O2 fault code.

I pulled some info from chevelles that seems to make sense, or apply.

Any input is appreciated.

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