Hope one of you can help me out or at least gives ideas on what else to try & check.
Must be overlooking something

Had a Duster for years (totally redone 4000miles ago) and after having not ues it for long time its hard to start but lately stopped firing up at all. Its a 340 pumpgas, solid cammed, x-heads, edl intake, holley carb, msd etc backed up by a 727. It cranks but will not start and only every now and then gives it a try to fire up but nothing much. Checked and replaced so many stuff already but no luck. Not even with brake cleaner...

Replaced or changed out (step by step) mopar distributor, msd blaster coil, battery, spark plugs, msd wires, fuel, etc
Checked compression and all cylinders on average between 150-160psi
Checked valve lash and all still fine.
Checked spark at coil wire and gives 1” blueish solid spark.
Get spark on the plugs as well.
Gets fuel from carb or brake cleaner.
Checked tdc vs balancer and is correct.
Timing havent changed but turning it both sides did not make any difference.

Got compression, fuel and spark but no luck.
Supplied full 13v to msd 6al with extra batt but no change.
Extra ground cables directly from engine to battery but no change.
Battery fully charged.

If in the end it starts its mostly after having it sit for 10mins so theres only like vapor in the intake. Still very hard but IF it fires up it runs fine as ever.

Cranking the engine it sounds a bit like theres no compression but test says its fine.
Feels like the spark is not lighting the fuel, and ir fuel not atomizing, lack of intake air speed or something.

Im out of ideas so anything is appreciated? What and how to check more?

Thanks a lot!
Hans

Did you check for fire while cranking with the key? The reason i ask is there is power form the ignition switch in two positions. Start and run.

Thanks!

Forgot to mention but the msd has power during crank & run as well as there is a spark during cranking.

and you are sure you have the timing set somewhat correctly in order for it to start ?
have you checked the distributor weights aren't sticking in a set position ?

Sometimes it makes an attempt to fire up but only a tiny one so sometimes it fires some cylinders but just not enough to get it running. Good tip about the distributor, will check that too

hi

your dist might be 180 deg off .

if rotor is not broken , lift dist snd rotate shaft 180 and try to start it .

make sure dist is turning when cranking .

Also check to see if the distributor is tightened down. Wouldn't be the first time I encountered a loose distributor
From there I would verify TDC and that the balancer hasn't slipped. Your description sound like retarded timing.
But verify things before you start changing them

I've had mixed luck with MSD. If it were mine, and I had a points distributor, I'd put it in and see what happens. 2¢

You have to be missing something. Compression, spark, fuel it should run. Unless the gas is no good, cranking to slow, improper timing. Timing as in camshaft like the chain is jumped.

Have you actually had somebody look at the actual voltage while you are cranking it?
Almost sounds like low/ marginal voltage. MSD acts weird with even a tiny bit low voltage.
If you have a good battery charger hook it up and put in on boost and try starting the car

As for the battery it wont start fully chargerd, nor in boost mode on the charger and neither with kables to my truck so its not the battery I would say.
As for fuel it's the correct one, fresh, but besides that, even with brake cleaner it does only gives an attempt by firing maybe one or two cyliinders, but no real start attempt.
Will recheck the timing again.

Was thinking about a leak down to double check / rule out other stuff but my compressor is not up to that task.
Thinking as cranking makes it sound like there is no plug in it but again the dynamic compression ratio is plenty on all 8.

Logically it should fire right up or at least try to...

You drained/refilled the carb bowls with fresh gas? as mentioned retarded timing. Just thinking out loud on this but could you sub in another coil? for sure post what you find

I would pull the plugs and see if they are wet. Squirt a couple shots of oil in each hole. Verify timing on TCD and the rotor pointing at number 1. Make sure the oil is not diluted with gas. Either clean or replace the plugs. And see what it does. Could be the rings are washed .

Put new spark plugs in it even if the old ones look fine. On more than one occasion, I've had gas fouled Champion plugs that would prevent the engine from starting even though they looked almost new. If you don't want to spring for new plugs, put the old ones in an oven at 450F for an hour, then install them into the engine as quickly as you can while they're still real hot, and fire it up.

as has been previously stated [by RR perhaps ?] please let us know what you find out.
the "loose" distributor has also bit me more than once ! you would think i would learn/"remember", but nooOOOO !

So you successfully put 4000 miles on this car and after sitting, now this starting problem has surfaced. Is that a correct statement?

Anyone remember a thread about a car that starts when you let OFF the key? As in, turn the key to "start" and it cranks, but won't start until the key is released and turns back to "run." I can't remember the cause (probably ignition), and can't find the thread. Thoughts on that???

That is either an ignition switch or more commonly it’s the bulkhead connector not making the connection on the start circuit to the coil.

I had the same issue with my barracuda. I spent weeks going through the same things you have done until I discovered that my trans had a small leak around the neutral safety switch (on the trans) that allowed fluid to pool up in the connector on the neutral safety harness and was shorting causing a no-start condition, I cleaned the plug on the harness as well as the prongs on the switch. Cranked right up! Wouldn't hurt to check!

this plus a bad resistor !

if you have the resistor with msd remove the resistor !