84 inline6 feedback conversion questions
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84 inline6 feedback conversion questions
So I recently bought an 84 F150 with the in-line 6 and a 4 speed granny transmission and it’s 4x4. The previous owner had the feedback carb completely disconnected and the connectors wiring that plugs into the distributor is altered. It was running super rich and smoking a lot of gas out of the exhaust. I got a non feed back carb on eBay and fixed all the vacuum leaks and it runs really smooth and idles great now with 20in of vacuum. My question is that I read in a lot of other threads that I need a duraspark 2 distributor and module which I have purchased just not installed and I’m 17 and still learning a lot about engine and I was wondering what difference it would make since it’s idles and runs good. Thanks- Colby
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From: Angier, NC
If you are still running the feed back dist. (TFI unit) it has no vacuum or mechanical advance.
Advance is controlled by the computer and because you are running a non-feed back carb the computer goes into "limp mode" and locks the timing.
Because it has no advance the motor will lack power and not run its best.
Dave ----
Advance is controlled by the computer and because you are running a non-feed back carb the computer goes into "limp mode" and locks the timing.
Because it has no advance the motor will lack power and not run its best.
Dave ----
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Junior User
Joined: Sep 2018
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If you are still running the feed back dist. (TFI unit) it has no vacuum or mechanical advance.
Advance is controlled by the computer and because you are running a non-feed back carb the computer goes into "limp mode" and locks the timing.
Because it has no advance the motor will lack power and not run its best.
Dave ----
Advance is controlled by the computer and because you are running a non-feed back carb the computer goes into "limp mode" and locks the timing.
Because it has no advance the motor will lack power and not run its best.
Dave ----
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From: Denver Metro Area, CO
Dude... have you actually *driven* the thing on the road in its current condition?
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From: Denver Metro Area, CO
Yeah, that occurred to me afterwards, my comment was my original, knee-jerk reaction without knowing much about the situation. 
If the timing isn't advancing, performance (acceleration) is gonna be crap. You could maybe get it up to highway speeds but you should be able to tell that something's wrong. People sometimes force that condition for a short time to pass an emissions test.
True limp-home mode won't let you get over ~30 MPH.
In any event, a non-computer-controlled ignition system is necessary to restore any sort of acceptable performance.
If the timing isn't advancing, performance (acceleration) is gonna be crap. You could maybe get it up to highway speeds but you should be able to tell that something's wrong. People sometimes force that condition for a short time to pass an emissions test.
True limp-home mode won't let you get over ~30 MPH.
In any event, a non-computer-controlled ignition system is necessary to restore any sort of acceptable performance.
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Sounds like he has a handle on the carb. When I started at Fedex we had thousands of new '84-85 E250s with the 300. No one could figure out how to keep the exhaust manifolds tight. Ditto my '85. After any long trip, I would be out trying to tighten that thing up.
EFI exhaust manifolds seem to be the answer. OP can find more info on that in the Six forum.
Good luck!
EFI exhaust manifolds seem to be the answer. OP can find more info on that in the Six forum.
Good luck!
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Yeah, that occurred to me afterwards, my comment was my original, knee-jerk reaction without knowing much about the situation.
If the timing isn't advancing, performance (acceleration) is gonna be crap. You could maybe get it up to highway speeds but you should be able to tell that something's wrong. People sometimes force that condition for a short time to pass an emissions test.
True limp-home mode won't let you get over ~30 MPH.
In any event, a non-computer-controlled ignition system is necessary to restore any sort of acceptable performance.
If the timing isn't advancing, performance (acceleration) is gonna be crap. You could maybe get it up to highway speeds but you should be able to tell that something's wrong. People sometimes force that condition for a short time to pass an emissions test.
True limp-home mode won't let you get over ~30 MPH.
In any event, a non-computer-controlled ignition system is necessary to restore any sort of acceptable performance.
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Junior User
Joined: Sep 2018
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Sounds like he has a handle on the carb. When I started at Fedex we had thousands of new '84-85 E250s with the 300. No one could figure out how to keep the exhaust manifolds tight. Ditto my '85. After any long trip, I would be out trying to tighten that thing up.
EFI exhaust manifolds seem to be the answer. OP can find more info on that in the Six forum.
Good luck!
EFI exhaust manifolds seem to be the answer. OP can find more info on that in the Six forum.
Good luck!
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Joined: May 2019
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Believe it or not, my dad disconnected all the emissions and the truck ran ok for a long time. im working on either restoring it to stock feedback/emissions system or duraspark/ restomod. not sure which is better. Thats for another thread.lol
Last edited by mountaintruck1; Jun 1, 2019 at 03:47 AM. Reason: add more detail
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