Davis DUI installation/evaluation (1 Viewer)

[GJCruiser]

Thought I'd post this for anyone seeking more input regarding the use of a Davis DUI. I recently made the decision to use one and I sought the advice of this forum for help. I received some input, wanted more, but "pulled the trigger" and bought one. I'm posting this as it couldn't hurt to have more ideas here.

Background- FJ40 running a 1978 small cap distributor ignition system failed (no spark) under heat, would cool down and run again until hot, then no spark. I ran "40" until ignition failure, took out of engine and wired it on bench while hot-no spark. Replaced coil and distributor pick-up coil with spares-no change. I decided not to buy a 45 year old used ignitor for $300.00 from someone who states "It ran when I shut it off four years ago". I wanted something new. I know all about non-Toyota admonishments-please, none for me.

Davis DUI and Livewires arrived after four weeks well packaged. Installation involved removing two interferences. I had to remove lower cooling pipe and reroute higher with continous heater hose. See photo. Also had to shorten rear stud (about 1/4 inch) which previously held said pipe onto lifter cover. That stud had about 1/4 interference with distributor body. Powered igniton with fused 12 AWG from existing aux fuse panel under hood for ham radio.

Engine started right up and timing was set to initial spec. I left spark plug gap at .035. No scientific comparison to report before/after. I will say this. I took timing up to 12 degrees BTDC per instructions and one can feel power through a nice acceleration "pull". I have not yet (and may not ever) opened plug gaps to recommended .055".

I'm very happy with the unit so far. Eventually, I will replace the bad ignitor with HEI module or Napa/Echlin part. Hope this helps.

 

[kerplunk]

Eventually, I will replace the bad ignitor with HEI module or Napa/Eichlin part.

Sorry, don't understand this part. Never really understood what the ignitor does, but thought the DUI distributor was basically an HEI unit tuned to fit an F/2F with a customized advance curve? So what are you still trying to replace?

I have one (D.U.I. distributor) on order, seems there back ordered, being patient as summer disappears...

But I had replaced my original dizzy with an HEI thing off ebay several years ago. The original to me distributor was already modified, (I think pertronix installed maybe?) and was always doing something different, every time I drove it different problems, and if I remember, timing always seemed to be "off", like it'd move between checks with a timing light somehow. With the HEI, it hasn't performed well, but it's been consistent poor (having noticed recently the vaccum advance doesn't move, doesn't actually look like it's broken, just machining issue and never worked), and that reliability was an upgrade...

Having already moved the heater pipe and been using plugs w/ .40 gap, and wires that aren't too old that fit the HEI cap I'm expecting it'll just swap. And hopefully some of the erratic pops and coughs might go away, and the stumble under acceleration....

 

[GJCruiser]

Sorry to confuse anyone. The ignitor takes the input from the distributor pickup, and along with the coil, in return, electronically fires the distributor high tension center lead. The DUI is exactly what you understand. It is standalone in that it replaces stock distributor, coil, and ignitor. It replaces all three.

What I wasn't clear on is, alternatively, there are other aftermarket ways (I chose not to) to substitute for the ignitor aka the HEI 4-pin module, or the NAPA TP50. These are all custom methods to keep the stock distributor. I meant I would make my dead system work again by substituting something for the ignitor to use as a spare or for my other vehicle, an FJ55. I confused you by stating I will go back and make the Toyota ignition work again. Just not for the FJ40. This Davis DUI fits, runs, and is very clean under the hood-its staying. My Toyota system had no pops, coughs, or stumbles. It just developed an intermittant heat issue which I could not live with. I don't know what HEI you are running now but the DUI is a standalone which is set up for the 2F. Mine is strong and smooth. Hope this helps.

I will say they told me their lead time was two weeks before I placed the order. That turned into 4 1/2 weeks and I wasn't happy with their bedside manner over the phone. The eventual product is exactly what I hoped for.

 

[tls3601]

So why are you not running the .050 spark plug gap? My ‘76 is set at 12 degree BTDC and runs excellent. I thought Davis reccomends the .050 gap, up from what I think was .032 stock ignition. I wish the heater pipe would fit, I don’t like having a hose that close to motor.

 

[residualboulders]

I've just installed the DUI on my 1979. I had to do the same mods @GJCruiser mentioned to get it to fit.

I cannot get mine started. Engine work has never been my strength, mostly because I've been lucky with good dependable 2fs in the various cruisers I've owned, ha ha. I've never had to do much other than get a carb rebuilt or replace worn out parts. I think I must be doing something wrong. I opened the window on the flywheel and pushed the truck in 4th gear to get the flywheel rotated so the bb lines up with the timing needle. Using a screw driver rotated the slot in the bottom of the distributor hole to line up about with the 3rd cylinder so that when the distributor is installed the black tip on the rotor is pointing to #4. Using new livewire cables, new spark plugs but I have not changed the gap. Cranks and cranks but will no start. A couple of times it sputtered but I think it was just excess fuel from cranking. I have Sniper EFI which was working fine with toyota distributor and stock coil/igniter - it just wasn't running great so I figured I'd try the Davis DUI. Kinda regretting it so far, ha ha.

I must be doing something wrong. Any ideas?

 

[Chungas Revenge]

May be 180* out.

Also, @wngrog gave me a pro tip on this adapter. Plugs directly to your dizzy. Pink to 12v switched.

Gap on the plugs is .050

@residualboulders

 

[wngrog]

I had problems with .050 gap. Started doing .040

 

[Chungas Revenge]

I had problems with .050 gap. Started doing .040

I‘m dead on @ .050

Problems in conjunction with a Sniper installation?

 

[residualboulders]

May be 180* out.

Also, @wngrog gave me a pro tip on this adapter. Plugs directly to your dizzy. Pink to 12v switched.

Gap on the plugs is .050

@residualboulders

View attachment 3463327

Where did you get this harness? Just grounded and pink to 12V?

I bought a DUI dist. harness from @Coolerman and wired it as per his suggestion. I'll check my plug gap.

 

[Chungas Revenge]

I usually refer to electrical work on my LC as “Dark Magic”. So I get the apprehension.

It’s a common auto parts store adapter. Trying to remember the product code. I saved the package in my box of “gee, I don’t want to forget this in case I need a new one Someday” treasure stash. It’s somewhere in one of three storage blds at the moment.

I used the 12v switched at the old coil. It’s a black wire/yellow stripe. This B/Y wire is in my connected to the pink wire from the DUI. The green wire is not a ground, it’s actually for a tach.

If your running a Sniper , 12v switched at the carb is used for the Sniper. Coolerman makes an adapter for this too.

caveat: I’m desmogged, no coil obviously and no igniter.

 

[residualboulders]

I usually refer to electrical work on my LC as “Dark Magic”. So I get the apprehension.

It’s a common auto parts store adapter. Trying to remember the product code. I saved the package in my box of “gee, I don’t want to forget this in case I need a new one Someday” treasure stash. It’s somewhere in one of three storage blds at the moment.

I used the 12v switched at the old coil. It’s a black wire/yellow stripe. This B/Y wire is in my connected to the pink wire from the DUI. The green wire is not a ground, it’s actually for a tach.

If your running a Sniper , 12v switched at the carb is used for the Sniper. Coolerman makes an adapter for this too.

caveat: I’m desmogged, no coil obviously and no igniter.

thanks for the info. I'm desmogged too. I have the coil and igniter but not hooked up to anything now that i have installed the DUI. Planned to remove once it get it running and sorted.

 

[Chungas Revenge]

This may help too..

1. Timing mark (starting point).
2. Black/yellow to pink wire
3. ”Plugged in to the Dizzy.

 

[kerplunk]

thanks for the info. I'm desmogged too. I have the coil and igniter but not hooked up to anything now that i have installed the DUI. Planned to remove once it get it running and sorted.

Remember the flywheel turns around twice for every rotation of the distributor.... (#1 on TDC of the compression stroke, not the exhaust stroke). I'm pretty sure you can just re arrange the plug wires to "fit" is it's 180 off....

Search amazon for HEI plugs and you can find many, with a crimper and a pin puller can make it look like it was made to be there from the start. But just jamming a very standard 1/4 inch (2.5 mm) quick disconnect terminal will work (the plug just has two of these inside, but does help secure it):

FASTON terminal - Wikipedia

en.wikipedia.org

(I drove mine around for years using just the quick disconnect terminal until I finally decided to clean up some wiring.)

The red (right side? looking at the plug toward you on the dizzy) should be ~ 12v+. If in doubt you could wire straight off the battery, just keep in mind the engine might keep running until you cut / disconnect it if you do. (and remember to unplug, not sure if you can burn up anything leaving it on and not running too long, I make sure I just don't risk it).

 

[residualboulders]

Remember the flywheel turns around twice for every rotation of the distributor.... (#1 on TDC of the compression stroke, not the exhaust stroke). I'm pretty sure you can just re arrange the plug wires to "fit" is it's 180 off....

Search amazon for HEI plugs and you can find many, with a crimper and a pin puller can make it look like it was made to be there from the start. But just jamming a very standard 1/4 inch (2.5 mm) quick disconnect terminal will work (the plug just has two of these inside, but does help secure it):

FASTON terminal - Wikipedia

en.wikipedia.org

(I drove mine around for years using just the quick disconnect terminal until I finally decided to clean up some wiring.)

The red (right side? looking at the plug toward you on the dizzy) should be ~ 12v+. If in doubt you could wire straight off the battery, just keep in mind the engine might keep running until you cut / disconnect it if you do. (and remember to unplug, not sure if you can burn up anything leaving it on and not running too long, I make sure I just don't risk it).

would you reposition the plug wires? or just pull the dist out and rotate 180 degrees? I guess that accomplishes the same thing, so just flip the orientation of my plug pattern?

I guess I should have asked - according to the HEI instructions I positioned the wires in the same pattern as the 1-6 labels on the stock dist. cap. Is this correct?

 

[kerplunk]

would you reposition the plug wires? or just pull the dist out and rotate 180 degrees? I guess that accomplishes the same thing, so just flip the orientation of my plug pattern?

I guess I should have asked - according to the HEI instructions I positioned the wires in the same pattern as the 1-6 labels on the stock dist. cap. Is this correct?

1 5 3 6 2 4

Clockwise.

toyota 2f firing order - Google Search

With the BB on the firewall under the pointer in the window, #1 cylinder (in the front) should be either in the post on the cap immediately on top of the rotor is, or 180 degrees off that, directly opposite.

Once it starts, tune with a timing light turning the distributor.

(this all assumes your wires are all long enough, I got autozone's in house special for a '78 Camaro, cause it had a straight 6 with the same style HEI posts on the cap.)

 

[wngrog]

The HEI does not care where #1 starts as long as you maintain the firing sequence.

 

[residualboulders]

The HEI does not care where #1 starts as long as you maintain the firing sequence.

Which is the same as the stock sequence correct? I just monkeyed with it for a couple of hours. Almost got it started. Started running when holding the key then killed soon as I let go. Should the rotor point right to #4 plug or a few degrees to one side or the other?

 

[kerplunk]

Check the window on the float bowl and make sure you do have gas in the carburetor.

And, probably easier with two people, or a remote for the starter, and yes, turn the dizzy a little side to side while cranking.

 

[wngrog]

Which is the same as the stock sequence correct? I just monkeyed with it for a couple of hours. Almost got it started. Started running when holding the key then killed soon as I let go. Should the rotor point right to #4 plug or a few degrees to one side or the other?

You can monkey with the dissy and get it pointed at one of the cap points.

 

[CondeCruiser]

Little late here. I got my harness kit from @Coolerman.

Cruiser Wiring