400 will not start after maintenance...grrrr...Yeah!

[AKcharger]

My '72 just will not start after I did some work to it,  Of course I'm missing something and/or something Is bad...so  what am I missing and where should I start?? Disclaimer...this isn't my 1st rodeo I know all the normal hiccups but I'm getting stumped here  

INPUT CONDITIONS
Car running fine but suffered from vapor lock when hot so performed the same modification as I did on my '70, new intake gasket to block heat risers and "cool carb" heat shield. Last gas Fill Up around Aug and ran fine, no problems. while I was at it I also:
- pulled distributor and painted engine
- New plugs (all gapped to .032)
- New plug wires
- New carb edelbrock 750
- New fuel filter

PRE-START
- I took a photo of distributor with cap off and DID NOT ROTATE ENGINE...I replaced same distributor in the EXACT same position
- All plug wires are PERFECT...I even labeled them and recheck no less than 15 times
- Timing set to TDC and rotor is EXACATLY on #1

ON INITIAL START
- Back fires through carb (adjusted timing a bit)
- Backfire through exhaust (checked all wires)
- Still backfires...double check DTC
- rotate distributor 180..."just in case" nothing..but pack dist.

NOW
- I don't get anything. I get one "pop" through carb is I give it a squirt of starter fluid...that's it
- No back fires through carb or tail pipe
- Just spins over

WHAT I'VE TRIED SINCE
- Replaced ECU...nothing
- New cap/rotor...nope
- Replaced distributor...nope
- Ohm'ed ballast resistor it was good
- tried an old carter AVS and a new Edelbrock 750..nothin
- Put timing light on #1 wire and its flashing when I turn engine over so I'm getting spark
- Spun dist. 180° out again, just in case..still no
- Carb is getting fuel

So I've got Fuel, Spark, Compression and Timing but it ain't working...what do you suggest 1st??

Thanks


-

[c00nhunterjoe]

If it spits through the carb, it sounds like timing. But its hard to think with that girl bouncing around.

[AKcharger]

Understand about the chick sir...Nope with timing its set at TDC then I advance  and retard it incrementally expecting it's off a little...nothing

[c00nhunterjoe]

If it wont run on spray, then it's either no spark, or timing.

Verify tdc on compressions stroke via pulling no 1 plug, line up mark on balancer, line up distributor to no1 wire and retry.

[AKcharger]

Copy..Pulled #1 plug used straw to make sure piston was full up on COMPRESSION stroke reinstalled plug. TDC on balancer and rotor pointing right at #1....
This is hat it looks like

[69wannabe]

Is the ECU grounded good. Had to add a ground from the engine to one of the ECU mounting screws to get a good ground on my charger. Also double check all the spark plug wires and the firing order. The rotor button turns counter clockwise on a 400 and it's easy to get the plug wires crossed up too.

[69wannabe]

Oh yeah, try a new coil!! I had one crap out on me sitting in the yard. Was running one minute then turned it of and it wouldn't start back up and it was a bad coil. I didn't see coil in any of the things you have replaced.....

[Nacho-RT74]

unplug ECU, and check for continuity ohms test between Tan and brown wires at that plug ( 150 to 900 ohms, being around 250 rate  the most normal I have found ).

also none of these leads must be grounded. fully isolated, so can check againts engine ground to check is isolated

[AKcharger]

Coil and ECU check...let me look

[Nacho-RT74]

Not ECU check, but the dist pickup coil ohms at that plug. Also, being isolated from ground

[Kern Dog]

I see a few errors but nothing stands out a being the main cause.
Spark plugs should be gapped at .035 not .032.
Ignition timing needs to be BEFORE TDC, not at TDC. Even a stock engine can benefit from 7-10 degrees of advance at idle.
Have you checked the air gap in the distributor? In the V8, there are 8 points on the reluctor wheel that spins with the shaft and rotor. The points of the wheel are to be gapped to the magnetic pickup at .008 using a brass feeler guage.

[BSB67]

Copy..Pulled #1 plug used straw to make sure piston was full up on COMPRESSION stroke reinstalled plug. TDC on balancer and rotor pointing right at #1....
This is hat it looks like

Is this your#1 TDC firing rotor position?  If so, you have either a unique wiring arrangement on your cap, or the distributor is in wrong.  #1 should be at about the 5 o'clock position when viewed from the passenger side fender.

Oddly, it's not out 180° either.

[AKcharger]

Is this your#1 TDC firing rotor position?  If so, you have either a unique wiring arrangement on your cap, or the distributor is in wrong.  #1 should be at about the 5 o'clock position when viewed from the passenger side fender.

Oddly, it's not out 180° either.

No sorry, I guess that photo is misleading. that's the photo I took when I pulled the distributor. I put it back in EXACTLY the same...but really it's not far from where it points at TDC

- Air gap...I'll check but it's the distributor I had on the '70 so it's good (Installed a fire core in that car
-and ohm check let me look into that

[Nacho-RT74]

I see a few errors but nothing stands out a being the main cause.
Spark plugs should be gapped at .035 not .032.
Ignition timing needs to be BEFORE TDC, not at TDC. Even a stock engine can benefit from 7-10 degrees of advance at idle.
Have you checked the air gap in the distributor? In the V8, there are 8 points on the reluctor wheel that spins with the shaft and rotor. The points of the wheel are to be gapped to the magnetic pickup at .008 using a brass feeler guage.

that could make it work better or worse, but will start up anyway

[Nacho-RT74]

Copy..Pulled #1 plug used straw to make sure piston was full up on COMPRESSION stroke reinstalled plug. TDC on balancer and rotor pointing right at #1....
This is hat it looks like

Is this your#1 TDC firing rotor position?  If so, you have either a unique wiring arrangement on your cap, or the distributor is in wrong.  #1 should be at about the 5 o'clock position when viewed from the passenger side fender.

Oddly, it's not out 180° either.

that's just if the driveshaft was installed per factory specs, with slot allmost pararallel to the camshaft and stock dist. But could be correct or not. At the end no matter where the 1 is pointing out as far is at the cylinder 1 compression stroke. If you use a MP dist ( laters one built by Mallory ) will find the dist rotor is around 90º off with dist/oil pump driveshaft installed per factory specs ( BTDT )

[Nacho-RT74]

about the pick up coil ohm test BUT FROM THE ECU PLUG! I have found sometimes the pick up coil plug doesn't make good contact with engine harness plug &/or pick up coil leads are grounded. This have got me never to fire up, or even backfires if grounded. That's why testing at ECU plug makes to check the good conection on dist plug,

THE TIPICAL DAMAGES on dist pick up coil are, leads broken or coil grounded due the heat inside the assembly. Handling the dist here and there, specially old ones takes to this

just my experience.

NOTE:

have you tried to find if coil is getting out sparks ? do you know how to do it ? getting the wire running to central terminal of dist cap close to chassis around 1/4" gap and cranking to check if gets sparks.

If yes, the problem is dist cap/rotor related or timming

If not
Damaged ECU
ECU not propperlly grounded
ECU not getting 12 volts on RUN or 8-9 Volts on START ( this could take to ign switch or ballast, or related wires ). Blue traced yellow wire
ECU plug loosen, Dist Plug loosen. Damaged related wires ( continuity allong the black traced yellow wire with - lead of coil )
Damaged coil
Coil not getting 8-9 Volts on RUN and 12 volts on Start ( same note as ECU above ) at brown wire

that pretty much sums out the testing

[Nacho-RT74]

another notes:

have you checked the leads of coil are really correctly setted up ? brown to +, black traced yellow to - ( it happened once to a member and that was the fail ). It seems burnt out two ECUs with these reversed

4 or 5 pins ECU with single or dual ballast ?

[birdsandbees]

I'm just glad for the thread... made me go pull my distributor to find my drive gear was one tooth off.. has been for 38 years. Always wondered why my vacuum advance was almost pointing forward. 

And YES.. the rotor when firing #1 should be at about 5 o'clock. not 11.

[Kern Dog]

That looks pretty dry in there. Is that an old picture ?

[birdsandbees]

Yep... 15 minutes old before I coated everything in 10W30 when putting the drive shaft back in!   . No wear on anything... remember it's sat for a year now since I tore the car down.

[Nacho-RT74]

I'm just glad for the thread... made me go pull my distributor to find my drive gear was one tooth off.. has been for 38 years. Always wondered why my vacuum advance was almost pointing forward. 

you could simply swap around all spark plug wires one or two steps forward without pay attention on the mark 1 on cap ( if marked ).

just an idea... I preffer to meet the factory locations reindexing the dist driveshaft too LOL

[BSB67]

you could simply swap around all spark plug wires one or two steps forward

Or you could take 15 seconds and fix it right.

[Nacho-RT74]

LOL, is about prefferences. I'd reindex, but lot of ppl simply swap around the wires.

[c00nhunterjoe]

you could simply swap around all spark plug wires one or two steps forward

Or you could take 15 seconds and fix it right.

Yup. If you just pulled the distributor, just reindex the gear. Takes 10 seconds. 15 if you have to rotate the pump. Peice of cake.

[birdsandbees]

Exactly guys.. used a long pair of foreceps that I use for getting hooks out of fish.. and just pulled it out, lubed and returned it a tooth over so the slot lined up parallel with the camshaft. Now my vacuum module is pointed more towards the left rocker cover end than the radiator!