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So I have a 1985 f150 with a straight 6 and I am getting crappy gas mileage like single digits and a lack of power in 3rd gear everything on the truck is fine except for an exhaust leak, starts up great and runs smooth so I'm thinking it is the timing curve and want to swap out to an older vacuum advance distributor with less electrical components. Two questions does anyone have experience with the distributors with a built in coil pack and what would I have to do to swap out the distributor to an older style one
This I the mess I have right now
Last edited by Redneck11; 04-27-2017 at 12:36 PM.
Reason: messed up typing
I swapped over to the HEI distributor when I got rid of my feedback carb and computer. The only thing you have to do to make it work is install a relay to send 12v to the coil when the key is on.
30 is (+) in from my battery, 87 is (+) out through the relay to the coil, 85 is coming back up to the screw to ground it, and 86 is the 12V that is hot when the key is on to trigger the 30-87 circuit.
Other than that, just make sure you find a ported vacuum source that's pulling zero at idle and only pulls vacuum when you put your foot on the gas. I'll take a picture in a minute to show you where I'm getting mine.
Last edited by chupa; 06-22-2017 at 08:15 AM.
Reason: Added distributor info
Clarification for anybody else who is reading, I had to install the relay because I tore out my old wiring harness so I didn't have The old wires to the coil to give me 12 V with the key on. If you still have the old wiring harness I'm guessing one of the wires to your coil can just be cut from the connector and spliced to the new distributor.
I will wire in a tachometer Relay operated by old coil wire
Everything went very smooth with my swap other than the fact that I mistakenly forgot to pull off the shaft that drives the oil pump and install it on my new distributor. After I removed everything and installed it on the new distributor and found out my timing was off by 180° everything went well. I have noticed a slight improvement in gas mileage and major increases in horsepower at least it feels that way.
Hi, old post but so helpful! I am doing this install on my 1984 F-150 inline 6 right now. I still have the old wiring harness after taking out the old dizzy.
So if I have the wire that went to the old coil I can just use that to the batt input on the HEI? No need for the relay? Although the relay looks cool.
Thanks!
Josh
Hi, old post but so helpful! I am doing this install on my 1984 F-150 inline 6 right now. I still have the old wiring harness after taking out the old dizzy.
So if I have the wire that went to the old coil I can just use that to the batt input on the HEI? No need for the relay? Although the relay looks cool.
Thanks!
Josh
I think that’s correct. If you have the old 12V that feeds the dizzy from the battery when the ignition is on, you should be good. One thing I’ve learned since originally posting on this thread: if you use a relay you have to be careful where you put it and/or wrap it to protect from water. Went through a car wash and the damn thing died half way through because the relay got wet. Had to push it out of the way at the end so the car behind me didn’t rear-end me! 🤣
04-27-2017, 12:16 PM
1985 f150 4.9 distributor swap
