84 Bronco with feedback style Carb

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84 Bronco with feedback style Carb

Postby Craigwell » Sat Jan 02, 2010 12:38 pm

Any hope of keeping the feedback version of the YF in a truck we converted back to DSII?? I've already had to mess with the set screw that rests against the old idle solenoid to keep a reasonable idle, but are there other issues that will present themselves to make this not worth our time?
1995 F150 4x4 4.9L E4OD Mule / Plow Truck
Gone but not forgotten: 1976 F250 4x4 300 six, NP435. Dana60/44HD 4.10 Traction Lok, EFI Exhaust, 240 Head
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Re: 84 Bronco with feedback style Carb

Postby Ranger_gone_straight » Sat Jan 02, 2010 12:54 pm

Do a search for the nutter modification of feedback carb on 258 straight six on the Jeep boards. Basically you get little stepper motor that adjusts mixture to compromise position and then disconnect wiring to it so it stays there permanently. Some people are happy with it. Unless forced to by emissions laws in your locality, I would rather find a non electronic carb.

Never heard of anybody doing it, but wonder if mega squirt could control feedback carb? Feedback carbs do get good mileage when they are working properly.
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Re: 84 Bronco with feedback style Carb

Postby Craigwell » Sat Jan 02, 2010 6:58 pm

I have read the nutter article, and specifically one that speaks about the feedback YF.

I'm still trying to sort out what some of the electric components are, but I don't know if there is a mixture control device.

This one we are dealing with still has the traditional idle mixture screw. The only electronic appendages I can determine seem to be curb idle solenoid, some kind of TPS or WOT sensor? It is attached to the throttle shaft.

I'm casting about for some more plain jane YF or YFA's, but trying to make what we have work for the time being.
1995 F150 4x4 4.9L E4OD Mule / Plow Truck
Gone but not forgotten: 1976 F250 4x4 300 six, NP435. Dana60/44HD 4.10 Traction Lok, EFI Exhaust, 240 Head
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Re: 84 Bronco with feedback style Carb

Postby Ranger_gone_straight » Sat Jan 02, 2010 7:19 pm

They arent talking about idle mixture, but the internal metering rod that adjusts mixture during normal driving rpm. In feedback carb, a small stepper motor constantly adjust the metering rod directed by computer, instead of using vacuum or mechanical linkage like in a non feedback carb. Stepper motor will be screwed into the side of the carb with two or three wires to it. Should be around half way to two thirds up side of the carb. Its not the throttle position sensor or other gizmos attached to the throttle shaft.
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Re: 84 Bronco with feedback style Carb

Postby Ranger_gone_straight » Sat Jan 02, 2010 7:21 pm

Getting dark here or I would go dig out one out of my scrap box and post a picture. I keep them around as sometimes they can donate parts to a non-feedback version.
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Re: 84 Bronco with feedback style Carb

Postby Craigwell » Sat Jan 02, 2010 10:43 pm

Your right.. found another thread in my googling of the matter. Question is how rich does the carb run in default without the metering feedback solenoid connected.

I'm going to get a few spare YF's, I've rebuilt a few without incident. Gave a couple to a guy once that wanted to test out something, and never heard anything back. I gave him a ring tonight! :D
1995 F150 4x4 4.9L E4OD Mule / Plow Truck
Gone but not forgotten: 1976 F250 4x4 300 six, NP435. Dana60/44HD 4.10 Traction Lok, EFI Exhaust, 240 Head
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Re: 84 Bronco with feedback style Carb

Postby Ranger_gone_straight » Sun Jan 03, 2010 12:05 pm

I took pic this morning. I'd have to go read the Nutter article to refresh my memory on how he set the adjustment since I've never done it, just read about it. Its a compromise setting to approximate where metering rod should be during moderate driving conditions, you dont just disconnect the stepper motor as is, you have to set it as per the Nutter article and THEN disconnect the stepper motor electrical connection. This locks the metering rod to a halfway compromise position since without being electrically connected, the stepper motor is dead and cant move the metering rod one way or the other.

The Jeep people seemed to do ok with it, ok mileage without running lean enough to do damage. Its not going to be optimal, but I assumed you knew that when asking how to use feedback carb without whole feedback system functional. There is no way to make a feedback carb into a perfect non-feedback carb, the Nutter approach is as close as it gets from what I've heard, and sure beats running feedback system in super rich limp home mode.

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Re: 84 Bronco with feedback style Carb

Postby Craigwell » Sun Jan 03, 2010 12:34 pm

Thank you very much Ranger, I appreciate your time on the matter. Nice pic, I do know that we are talking about the same component now, which is getting closer!

My nutter googling let me to several references to the BBD, but only one to the YF. The one regarding the YF spoke of removing the solenoid/stepper motor and blocking the area off with a plate, and also plugging an "angled bleed" metering passage. I cannot find reference to applying voltage to the stepper motor to trick it.

I'm going to find a standard YF or YFA for this vehicle (not mine) before I go that far, but in the meantime if I can get a compromise from the default rich condition, or perform a one time direct voltage application to get the stepper motor to move things to where It becomes the best compromise then we might call it good enough until the proper YF's come home.

I'm sure it will tease out either way, time being solution :)
1995 F150 4x4 4.9L E4OD Mule / Plow Truck
Gone but not forgotten: 1976 F250 4x4 300 six, NP435. Dana60/44HD 4.10 Traction Lok, EFI Exhaust, 240 Head
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Re: 84 Bronco with feedback style Carb

Postby THE FRENCHTOWN FLYER » Sun Jan 03, 2010 10:03 pm

Craigwell wrote:... or perform a one time direct voltage application to get the stepper motor to move things to where It becomes the best compromise then we might call it good enough until the proper YF's come home.


Lest somebody get confused reading this the voltage needs to be applied in individual pulses starting from a known starting point to position the motor armature in a specific location. I forgot how many pulses it takes to step it from the max lean condition to the max rich condition but I think it might be about 100 or 150. Applying voltage once to the motor would only move it one step, an infinitesimal amount.
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Re: 84 Bronco with feedback style Carb

Postby Craigwell » Sun Jan 03, 2010 11:05 pm

Now that is interesting. One of our YF's did turn up today and is slated to go on the rig, but we have two of these feedback carbs now, and will experiment. Good to have them around for parts, and when the normal ones get scarce I suppose.....

Thanks all!!
1995 F150 4x4 4.9L E4OD Mule / Plow Truck
Gone but not forgotten: 1976 F250 4x4 300 six, NP435. Dana60/44HD 4.10 Traction Lok, EFI Exhaust, 240 Head
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Re: 84 Bronco with feedback style Carb

Postby Craigwell » Sun Jan 03, 2010 11:34 pm

FTF: do you think straight 12V would be ok for these incremental moves, or is it too much??
1995 F150 4x4 4.9L E4OD Mule / Plow Truck
Gone but not forgotten: 1976 F250 4x4 300 six, NP435. Dana60/44HD 4.10 Traction Lok, EFI Exhaust, 240 Head
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Re: 84 Bronco with feedback style Carb

Postby Ranger_gone_straight » Mon Jan 04, 2010 11:12 am

Definitely post your results if you experiment with this, sure there would be others interested, though getting to point I imagine engines with the feedback carbs still in use are getting rare. They were only used for 2 or 3 years and when they started giving problems, most people replaced them with old non-feedback carb.

I am already not thrilled that prices on older YF and YFA rebuildable cores (good ones where you just clean them and throw in a kit) are getting higher as carbs go way of the dinosaur and disappear from junk yards. I suppose worst come to worst, can always use 2bbl adapter and brand new Holley or Weber aftermarket carb. Hopefully still some years away from that as they tend to go for more $$$ than good used engine. course they are probably going to be in pristine condition unlike some of crappy parts store rebuilds that are being sold now, just would have to properly jet them.
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Re: 84 Bronco with feedback style Carb

Postby Lazy JW » Mon Jan 04, 2010 11:34 am

Ranger_gone_straight wrote:Definitely post your results if you experiment with this, sure there would be others interested.....

Yes, enquiring minds want to know, please share your findings.
Thanks,
Joe
74 F-350 300-6, EFI manifolds into single exhaust, Carter YF, T-18B, Dana70 w/4.11, Flatbed dually w/dump bed. Great farm truck!
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Re: 84 Bronco with feedback style Carb

Postby RiverSteve » Sun Feb 21, 2010 9:58 am

I tried with my 85 with a YF until I was at my wits end. I just converted over to a quadrajet with a offy intake and there was far more information available on the conversion than trying to get the yf to work. I have a new YF for an 85 and a rebuilt if you need. Sorry I cant be more help. good luck
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Re: 84 Bronco with feedback style Carb

Postby Craigwell » Mon Feb 22, 2010 6:14 pm

We didn't mess with the stepper motor. We made sure the truck was running as well as it could with timing, and such. and only found the truck running a tad rich. Vacuum was good, as was driveability.

We put a standard YF on the truck, and gained a little better mileage, and that's where we left it.

If needed, the feedback units are still on hand, if only as parts donors.....
1995 F150 4x4 4.9L E4OD Mule / Plow Truck
Gone but not forgotten: 1976 F250 4x4 300 six, NP435. Dana60/44HD 4.10 Traction Lok, EFI Exhaust, 240 Head
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