Considering conversion from feedback system to Duraspark II

[Colebla]

I have a 1986 f-150 300 I6 with carter yfa feedback carburetor and EEC-IV. I am wondering how hard a conversion off of my computer controlled carburetor would be. It seems like the most common option is a Duraspark II ignition combined with any manual carburetor. Does anyone have experience doing this? Thanks!

From what I can tell, all I will need is the following (please correct if wrong)

Any distributor for a 1980 f-150 300 I6 (my understanding is these are all duraspark II?): https://www.rockauto.com/en/moreinfo.php?pk=1130628&cc=1121128&pt=7108&jsn=1273

Wiring harness for the duraspark distributor: https://www.summitracing.com/parts/prf-30812

ICM: https://www.rockauto.com/en/moreinfo.php?pk=1949676&cc=1121128&pt=7172&jsn=1262

and ignition coil: https://www.rockauto.com/en/moreinfo.php?pk=12493945&cc=1121128&pt=7060&jsn=1281

And of course a new carburetor of some kind.



OR

I can go the HEI route, in which case I need:

A distributor + wires


and a new carburetor?

Is that it? I guess I would need to find/fabricate a manual choke as well, and decide on a new carburetor.

[Gary Lewis]

The EEC-III system has to be complete and functioning or it'll get its knickers in a twist and lock your timing to base - and you'll have no power.  So you have to have all of it or none of it.

On the carb, David/1986F150Six put a 1970 YF carb off of an '70 F350 and it worked extremely well.  So I'd recommend going that way as it gave a great air/fuel ratio and good MPG.

For the ignition, you need a blue-grommet DS-II module, the wiring harness you mentioned, and a distributor with a vacuum advance.

And you'll want to block off the EGR as there's nothing to control it once you pull the computer.

Then, with the EGR blocked off you need to play with the vacuum advance to dial it is so you don't have pinging.  We did that on David's truck and you can read about it here and in the post after that.

[Rembrant]

Colebla wrote

Wiring harness for the duraspark distributor: https://www.summitracing.com/parts/prf-30812

The Painless DSII Wiring harness will work just fine. I'm installing the exact same kit in my 1952 pickup today.

Question for Gary or Jim though: Did the Non-DSII Bullnose gas trucks still have a ballast resistor in the harness? And would the brown wire from the "I" terminal to the coil be needed or not? Maybe that's a dumb question, I don't know...but I was wondering if a non-DSII truck is already setup for it in the harness?

Installing this kit in my truck today;).

[Gary Lewis]

Yes and yes.  The main harness didn't change between DS-II and EEC, just the engine harness.  So the ballast resistor is still there.  And you will need the brown wire with your setup.

Here's the wiring for an 4.9L EEC truck, but the others are the same:

[Rembrant]

Gary Lewis wrote

Yes and yes.  The main harness didn't change between DS-II and EEC, just the engine harness.  So the ballast resistor is still there.  And you will need the brown wire with your setup.

Oh yes, I know that I need the brown wire with mine, but was curious if the factory EEC trucks had all of the same ignition wiring as the DSII trucks. All good.

[Colebla]

Thank you!

I am thinking the HEI conversion + the 1bbl yf you mentioned (for a 1970 MY) might be the way to go for simplicity.

This kit is an HEI with adjustable vacuum advance like you mentioned.

https://swapmeetparts.com/product/ford-inline-straight-6-cylinder-65-76-240-300-4-9l-hei-distributor-plug-wires/

I’m thinking if I get this and the carter yf I should be good to go? I’ll replace distributor and carburetor and remove pretty much all the wiring, EEC, and distributor. Then I’ll tune the carburetor and adjust the vacuum advance. Does this sound like it would work?

[Gary Lewis]

I think that combo should work just fine. Do you know how to tune the carb and ignition?  On our page at Documentation/Electrical/Ignition and then the Instructions tab you’ll see instructions from Crane Cams.

[Rembrant]

I bought a cheap carb on Amazon for my 300/6 and it ran great! Not sure if it's still available, but here's a link:

https://forum.garysgaragemahal.com/New-Repro-YF-carburetor-for-the-300-six-tp70663p85580.html

I only had lines run to the PCV valve, the brake booster, and the distributor vacuum advance. Everything else was bare bones.

[Colebla]

Thank you Gary. I have some experience tuning modern racing carbs and I am hoping that will carry over. I'll check out those resources and fingers crossed it will go well.

[Colebla]

Thanks! I'll check it out.