Engine won't fire, can't find the gremlin

[wagoner]

Background
Fresh motor, it's done 400km since completion.
Got 11:1 comp, 292, twin 45s, 123ignition, headers etc. Freshly tuned on the dyno making 125rwhp 

Just before christmas it decided not start consistently.

Now it won't fire at all after driving it into my carport a few weeks ago - not even a cough. 
I've done the following:

Please note: leads, coil and dizzy are 2 months/400km old. 

 

Replaced the plugs gapped to .8

Checked floats and needle & seat

Checked pump jets

Checked fuel supply & pressure

Check all grounds

Checked compression all 160+ cold

Check dizzy is spinning

Checked coil primary (2.5ohms) and secondary (11.6kohms) resistance

Misted petrol down throats

Checked if I had spark on all 4 grounding them to the strut tower

Checked timing (it hasn't changed)

Checked & toggled the immobilizing function on 123

Checked & adjusted 123 maps

Checked leads

Used startyabastard direct on to throttle plates

Hotwired coil direct from 12 source

Removed negative on coil to be sure it wasn’t grounding randomly via tacho wire


I'm running out of ideas. Can anyone give me something else to try? 

Edited January 17 by wagoner

[tech71]

Still have the original dizzy? If so, install it and see if it runs..

[tech71]

35 minutes ago, wagoner said:

Checked if I had spark on all 4 grounding them to the strut tower

Just read that, I would still  try thr stock dizzy

[Son of Marty]

Try firing it with starting fluid, if it fires you have a fuel problem if not it's ignition.

[wagoner]

2 minutes ago, Son of Marty said:

Try firing it with starting fluid, if it fires you have a fuel problem if not it's ignition.

Yup, done that, we call it Start ya bastard down here in Australia 😂

[02Pilot]

Spark, fuel, air, compression. What did the plugs look like when you pulled them?

 

That said, I'd suspect that distributor before anything else.

[John76]

2 hours ago, 02Pilot said:

I'd suspect that distributor before anything else.

Me too.

You're getting everything you need (fuel, air, spark and compression), but not at the right place and at the right time.

 

Startyabastard....love it!

[visionaut]

I’ll go with either a dead 123, or the dizzy lost it’s timing datum, and is now firing but not near where it needs to to make the gas go boom…

 

Verify #1 @ TDC has rotor pointed at #1…

 

 

[wagoner]

1 hour ago, visionaut said:

I’ll go with either a dead 123, or the dizzy lost it’s timing datum, and is now firing but not near where it needs to to make the gas go boom…

 

Verify #1 @ TDC has rotor pointed at #1…

Yup, I did that early on. Lined up perfectly. 

 

 

 

[Chris_B]

Seems clear that this is an ignition problem, given that you have used "start ya bastard"...

 

What else is there? Boy, this is a tough one. Coil, or dizzy? Or, something really trivial like a bad coil wire.

 

 

[ray_]

Be sure the block is properly grounded.

 

Cheers,

[Mike Self]

From your original post, it was unclear whether you had spark at the plugs.  If you did, and the car had run nicely for 400km after the rebuild, the only logical thing is that your 123 dizzy has gone wonky.  Either that, or somehow the engine itself has jumped time (via the timing chain jumping a sprocket tooth or two).  

 

However, if you didn't have spark at the plugs, but voltage at the coil, and since you don't have a conventional dizzy (so no failing condenser, worn points etc), you might check the wire that runs from the coil to the distributor.  I had an intermittent no start (conventional dizzy) and had eliminated all the failure points (points, condenser, cap, rotor etc) and finally discovered the insulated terminal connecting the low tension coil wire to the dizzy was broken under the insulated cover and making intermittent contact.  The giveaway was that the distributor wouldn't function when the intermittency appeared.  That wire supplies the signal to the tach, so check your tach next time you crank the engine and see if it twitches.

 

And let us know whatcha find.

 

mike

['76mintgrün'02]

The original post said there was spark when the plugs were grounded to the strut tower, but didn't mention whether they sparked if grounded to the engine. 

 

 

 

  might be onto something.

[Hans]

Does it fire at all? How did you check timing? Keep in mind that it could be seriously flooded.

 

[Dudeland]

What coil do you have? 

 

If you have a 75-76, you need to remove the resistor wire or you aren't going to get 12v to the Dizzy. 

 

Check the 123 app and look at the dashboard, you should see almost battery voltage.   If you are seeing 10ish volts then you aren't getting enough juice and you likely have a resistor.

 

Is the dizzy getting voltage in the run position, not just the start position?  It could be a bad ignition switch.  

 

Although the 123 is a bit of gadgetry, the only consistent problem is the oil seal.  I can only recall 2-3 electronic failures posted to this site.