How did you determine what 12 degrees BTDC was?
Davis DUI installation/evaluation
- Thread starter GJCruiser
- Start date
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Using your timing light and the line on the flywheel.
Find the line with the light.
Turn dissy counterclockwise until you have 13 on your gun and the line on the pointer.
Ahh, I guess the problem is that my timing light doesn't have enough features.
MOTOV8R
SILVER Star
I read in another thread that the bb at the left side of the window is about 12 degrees. That is where I set mine.
Manifold or ported vacuum?
I'm still having no luck getting this going.
- I have rotated the flywheel so the bb lines up with the needle.
- Both rockers on piston #1 are up (spring not compressed) and a little jiggly and I think i can see the top of the piston in spark plug #1 hole. From what i understand that is TDC.
- Adjusted slot inside the distributor hole to about the 11:00 position so that when the distributor is seated the black tip of the rotor is pointed to #4 spark plug.
it would not start - swapped #1 for #6, 3 for 5, ect on the top of the dist. to flip 180 degrees - when trying to start it backfires which from what i understand means it's 180 degrees out.
I have the @Coolerman harness for my davis DUI. As per his instructions I have:
- positive lead to positive on the battery
- ground to negative on the battery.
- small black and yellow tapped into the small two pin connector wire for the coil.
- yellow wire to Regulator IG wire (black with yellow stripe).
cranks but won't start. I have rotated the Dist while cranking and cannot get it to start up. Any ideas? I was able to get it started with regular coil and fj60 distributor.
EDIT: Just read a note on @Coolerman's website that the 1978-1980 has a resistor wire built into the harness so it may not put out 12V of power where I have tapped in at the regulator. Would that prevent it from starting? Where is a better source for full 12V of power on ignition?
- I have rotated the flywheel so the bb lines up with the needle.
- Both rockers on piston #1 are up (spring not compressed) and a little jiggly and I think i can see the top of the piston in spark plug #1 hole. From what i understand that is TDC.
- Adjusted slot inside the distributor hole to about the 11:00 position so that when the distributor is seated the black tip of the rotor is pointed to #4 spark plug.
it would not start - swapped #1 for #6, 3 for 5, ect on the top of the dist. to flip 180 degrees - when trying to start it backfires which from what i understand means it's 180 degrees out.
I have the @Coolerman harness for my davis DUI. As per his instructions I have:
- positive lead to positive on the battery
- ground to negative on the battery.
- small black and yellow tapped into the small two pin connector wire for the coil.
- yellow wire to Regulator IG wire (black with yellow stripe).
cranks but won't start. I have rotated the Dist while cranking and cannot get it to start up. Any ideas? I was able to get it started with regular coil and fj60 distributor.
EDIT: Just read a note on @Coolerman's website that the 1978-1980 has a resistor wire built into the harness so it may not put out 12V of power where I have tapped in at the regulator. Would that prevent it from starting? Where is a better source for full 12V of power on ignition?
With the ignition on, you should be able to test for power at the plug on the distributor (right side of the plug, I think?) and the idle solenoid on the carburetor.
Power to the idle solenoid on the carburetor should make a very faint click or tap sound.... It might fire without this, depending on how much gas is there, but it's not going to idle long, if at all.
One of those $3 spark checkers from harbor freight will confirm if you are getting power all the way down to the spark plugs. Or, you could hold a plug wired up against the block, careful on not grounding yourself, if might be more than a tingle...
Make sure there is gas somehow getting to the engine. Starter fluid, whatever, something it can burn and fire. If you look down in the carb and push the throttle linkage, some should squirt.
Spin it back around and watch the valves open and close, you should see the exhaust valve open and close around the time the BB comes back around in the window on the exhaust stroke, intake valve open and close and the BB come back into the window in about 1/2 turn of the crank....
Where ever the rotor is pointed, mark that and make sure the #1 cylinder's plug is on the cap right above it.
I dunno if you've ever done this before or not.... I'm no expert, have maybe only done this 7 or 8 times in my life.... And it can be frustrating. But making absolutely sure you do have gas and it is wired properly, actually checking for spark, usually makes it a little easier for me to know there's not something else I'm missing and I've always managed to get it working (sometimes with a little jolt of starting fluid)....
Making sure I have spark and gas and thinking through the basics on how to line it up always worked eventually. It's not magic, if the valves are opening and closing, there's compression, fuel and spark, it's just making sure that spark's at the right time and it'll fire.
And backfiring is not always 180 degrees off, mine backfired plenty just rolling on down the highway with my old distributor and carb... Sometimes it's just too lean or whatever....
Use a multi meter to make sure. And pull a plug out and ground it, watch for spark on it. Dui isn't mechanical, it will need a certain voltage for the electronic "points" to work.... But that resistor shouldn't be wired to your regulator, should be near the old coil.
Thanks, I know I have spark and fuel because it ran with fj60 dist. I’m running a holly sniper on it. It ran before, just not as good as I think it should so I thought I’d try this DUI, thinking about going back to the Toyota distributor at this point. I’ve spent hours and hours on this. I’m sure it’s something simple.
I don’t have a ton of experience. Replaced my motor in my first fj40 when I was in high school so I did it then but it’s been 25 years. I’ve owned multiple cruisers since then but they’ve always only needed valve adjustments, timing adjustments or carb rebuilds. I’ve done lots of work on cruisers doing lifts, body, paint, etc. I guess I’ve been lucky not to have had to do a rebuild until now. It’s good to learn and I want to learn, but I also just want to drive it
Because you had spark with that dizzy doesn't automatically mean you do with this one.
You replaced the dizzy, coil and points. Everything that makes the spark except the plugs.
Does the sniper need to be plugged into it to work (i.e. tach connection?).
i don't think it needs a tach connection. but I could be wrong.
Chungas Revenge
SILVER Star
Can you post up some pics of your set up? Where you’re getting 12v witched on the DUI and 12v switched on the Sniper?
The more Visual cues you can show the better it will help.
The more Visual cues you can show the better it will help.
Does the sniper screen show an actual rpm when cranking? I'm sure you know, but if it does not read an actual number while cranking, it will never start. Also, can you hear the fuel pump working? If questionable, check the fuse and relay for the pump. (from the sniper harness)
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Yes RPMs when cranking and yes the pump is working, I can hear it and see fuel spray in the chamber.
I agree with Chungas Revenge suggestion for pics.
I was having difficulty understanding how you’ve got your DUI and Sniper wired, so I thought I’d post this pic. The Sniper manual makes you combine two diagrams (in your head) when you are wiring for the Sniper with DUI. I Photoshopped them together in this pic for my head. This is how my Sniper/DUI combo is wired. I do use the optional relay.
I was having difficulty understanding how you’ve got your DUI and Sniper wired, so I thought I’d post this pic. The Sniper manual makes you combine two diagrams (in your head) when you are wiring for the Sniper with DUI. I Photoshopped them together in this pic for my head. This is how my Sniper/DUI combo is wired. I do use the optional relay.
MOTOV8R
SILVER Star
If you can run it with the fj60 dist you should be able to pull the cap and mark exactly where the rotor is pointing. Then put the DUI in exactly the same. I re-did the wiring on my 79 and there is a resistance wire built into the harness going to the coil. Where are you getting ignition hot for your sniper, maybe you could use that?
Thanks for this. I'll double check my wiring tonight. I got frustrated yesterday and put the fj60 dist back in and it still won't start. I lay awake last night retracing everything in my mind. I must have messed something up with the wiring somehow when I switched to the DUI. It's usually user error for me, ha ha.
@MOTOV8R I'll try that too. Thanks all.
The DUI has two wires, power and tach. It doesn't require a tach, this outputs to the tach, and would be where the sniper connects if required.
If the sniper requires knowing the engine RPM, this is where it would get it from the DUI.
Having an instrument to view this is irrelevant.
That makes sense. I'll double check my wiring tonight and try again. Thanks
Reiterating Kerplunks statement.
The Sniper must read engine rpm and it reads it with the yellow wire. The yellow wire from the Sniper connects to the coil if using a stock dizzy, but it connects to the “Tach” terminal when using the DUI.
You don’t need a tachometer but:
If you use a tachometer with a carburetor and DUI combo, the tach connects to the “Tach” terminal on the DUI.
With the Sniper & DUI combo, the tachometer connects to the brown wire on the Sniper’s 10 pin connector and the Sniper yellow wire connects to the DUI’s “Tach” terminal.
The Sniper must read engine rpm and it reads it with the yellow wire. The yellow wire from the Sniper connects to the coil if using a stock dizzy, but it connects to the “Tach” terminal when using the DUI.
You don’t need a tachometer but:
If you use a tachometer with a carburetor and DUI combo, the tach connects to the “Tach” terminal on the DUI.
With the Sniper & DUI combo, the tachometer connects to the brown wire on the Sniper’s 10 pin connector and the Sniper yellow wire connects to the DUI’s “Tach” terminal.
