Methodical first start process? (1 Viewer)

[whitey45]

Modules are finicky as well

 

[pithicus]

This must be driving you nuts Johnjl.
I noticed in your first post you said you corrected an overly-advanced ignition .
Could it be that only when cranking, the wiring to the hei module is giving the 10 degrees advanced [or retard not sure] pulse, your timing light is showing 9 degrees before tdc, as set by you with your dizzy.
Once it stops cranking it reverts to normal mode,. That would mean your timing is set to 1 degree after top dead centre or 19 degrees before tdc. One way to test this is to pull the spade connector off the starter solenoid and run a wire from the solenoid straight to the battery. turn the ignition on and crank it over with the wire to + battery with your timing light active. If it reads 1 degree after tdc or 19 btdc, then your module i wired incorrectly.

I know this is a long shot but it is baffling as to why you cannot get it to run even with a dodgy carb setting.

If you know it's wired exactly the same way as before then this is probably a waste of time.
Keep us updated.

 

[JohnJL]

How are you checking spark? Put fresh plugs in, bet it starts!

Pulled the plugs, they were all rich and wet. Gapped them wider a touch to 0.050, touched them with a wire brush, cleaned and dried them off. Turned the motor over a few times with the plugs out, put everything back and ***maybe*** its a bit better. It still coughs and sputters for maybe 10 revolutions then dies.

 

[JohnJL]

On those 5 pin hei modules I know if you get the connections wrong it puts the ignition 10 degrees retarded [or advanced ?] . Is it all wired up exactly the same as before? Also the wires from the pickup coil have to be on their correct pins on the module.
Maybe whoever rebuilt the engine botched the cam timing lol. Just kidding, but I suppose it could happen.

I havent touched the module ever. I installed the DUI distributor 15 years ago and it worked great from the start. Did maybe 5000 miles on it, then tore the truck apart and now put back together. I suppose there could be an issue with the HEI unit but I have never even seen it under the cover and never switched any wires insire.

 

[whitey45]

You still haven’t said how you know you have good strong spark? Do you have a inline spark jumper? Wire wheel will not clean a plug, bead blast or new.

 

[JohnJL]

This must be driving you nuts Johnjl.
I noticed in your first post you said you corrected an overly-advanced ignition .
Could it be that only when cranking, the wiring to the hei module is giving the 10 degrees advanced [or retard not sure] pulse, your timing light is showing 9 degrees before tdc, as set by you with your dizzy.
Once it stops cranking it reverts to normal mode,. That would mean your timing is set to 1 degree after top dead centre or 19 degrees before tdc. One way to test this is to pull the spade connector off the starter solenoid and run a wire from the solenoid straight to the battery. turn the ignition on and crank it over with the wire to + battery with your timing light active. If it reads 1 degree after tdc or 19 btdc, then your module i wired incorrectly.

I know this is a long shot but it is baffling as to why you cannot get it to run even with a dodgy carb setting.

If you know it's wired exactly the same way as before then this is probably a waste of time.
Keep us updated.

THis is interesting....when I am checking base timing I am unplugging the starter solnoid spade terminal from the ignition switch and connecting one side of my remote starter. The other end of the remote starter switch is right on the battery + terminal. When I depress the remote starter switch I use my timing light to set the pointer just a scootch past the timing pointer. Am I testing the right thing? I have not touched the HEI wiring and the distributor worked before...

Thanks!

 

[JohnJL]

You still haven’t said how you know you have good strong spark? Do you have a inline spark jumper? Wire wheel will not clean a plug, bead blast or new.

The timing light triggers consistently, and if I pull a wire and put a dummy plug in it grounded I see a spark. Is there another test you recommend?
Thanks

 

[JohnJL]

If your float valve is stuck open you will have gas pouring out the bowl into the throttle bores and could cause a 'wet-plug'. If your slow circuit isn't working (no power to the idle cut solenoid, debris ect.) that would also cause trouble. Carbs are simple, and I wouldn't expect much on that front.

Have you tried capping all the vac lines from the intake?

Along the lines of Thebigredrocker's advice, valve spec can be checked, but you can also do a compression check.

Always make sure you have oil pressure when doing any cranking.

Hi, Float seems to work properly. It was running high at first ut I opened it back up and adjusted the 'tangs' and it seems to sit at mid level in the window. Might there be another probem there? A LOT of fuel is going in, even with the throttle screw backed off and the air/fuel mix screw out 5+ turns...

Yes all vacuumm lines are plugged. I did a compression check.

Yes I get good oil pressure.

 

[pithicus]

Am I testing the right thing

Keep using your remote start system and rotate the dizzy 10 degrees each way and and see if it starts
[probably retarding the dizzy is the way to go]
To clarify the hei extra pin is retard 5-10 degrees to help starting. Soooooo, if this theory is correct your timing is way too advanced in the run position.

 

[JohnJL]

All good ideas here...

@whitey45 suggested, “Make sure you have power to the dui in the run position”. As you stated, it’s cranking fine, but do you have power to the dui, when the ignition is in “run” position?

Your dui requires full battery voltage (e.g. no ballast resistor)... where are you getting power for the dui?

My (1978) dui power is fed from a relay, triggered (relay-86) by voltage on the 12ga BY wire.

When triggered, the relay provides full battery voltage to the dui, via relay(87). Battery-Pos to relay-30/51... ground to relay-85.

Speaking of battery... you mention two batteries. They are wired for 12vdc (parallel), not 24vdc (series)... right?

Performance distributors recommends spark plug gap at .050-055”... I gapped mine at .050”. They recommend timing at 12*BTDC... my timing is ~12*BTDC. My 2F screams with these settings.

Firing order (on my 2F) is. 1-5-3-6-2-4 is your firing order correct?

Does your dui have a vacuum advance module?

What fuel pump are you running? Does it pump enough volume? Should pump 1 cup in 15 seconds. Use @pin_head’s test instructions in post 2 —-> Fuel /air mixture problems?

If it doesn’t pump 1 cup in 15 seconds, the filter could be dirty, the carb may have a dirty screen at the fuel inlet, your hard fuel lines may have crud in them, your fuelmay be dirty, your fuel tank may be dirty, the fuel pickup may be blocked, by something floating into it, when fuel is pumped. With your symptoms, I would check/clean/replace each of the above.

That same post (above) has info about air-fuel mixture.

Always start with your fuel filter - make sure it’s clean... new is a cheap fix.

Set idle at 650rpm... if you can’t get that low, it’s probably running rich and/or you have a vacuum leak.

For, Air-fuel mixture: use the lean-drop method: remove the screw and check the pointy end for deformation. If deformed, try to source a good replacement, or carefully reshape it. Screw it all the way down... be careful NOT to tighten it so much that it deforms the point. Unscrew three full turns, start the engine and screw it back down until the engine starts to die. Back it off, to a point where it idles smoothly and doesn’t ping.

Make sure you have NO vacuum leaks.

Good luck!!

Thanks, some thoughts...

DUI gets battery voltage on a dedicated relay.
I followd you and tried gapping wider at 0.050. Maybe a bit better?
Plug order is my favorite mnemonic...15 too young 36 too old 24 just right
Yes DUI has a vacuum advance. Base timing seems unaffected by whether its hooked up or not (with a tee in the hose)
Stock new OEM fuel pump putting out lots of gas. New lines.
Yes I used the lean-drop method on this motor and carb before rebuild and planned to do agin...right the struggle is to get it to run more than 3 seconds!

 

[JohnJL]

Thanks all for your advice...I am going to work on it again tonight...

Since everyone likes pics...perhaps these will serve as a token of thankfulness for putting up and helping me with my struggles...

 

[JohnJL]

Here's another focussed question.

First is my throttle idle screw. Here it is with the white arrow and just acting upon the throttle lever at rest.



Here is my throttle idle screw when the choke is partially engaged. I have inserted a flat screwdriver to shoe there is a ~2mm gap between the idle throttle screw and the throttle lever, shown with purple arrow. Is this right? Is the choke supposed to act on the idle throttle lever when the choke is pulled?



Here is a mystery-to-me screw with red arrow. I couldnt find adjustment instructions...how should this be set at baseline?

 

[pithicus]

Great pics! Very nice.

 

[JohnJL]

Great pics! Very nice.

Thanks, and thanks for the help too.

 

[thebigredrocker]

I've seen FJ40Jim recommend discarding the TP screw if desmogged. Here's a thread with pics where Jim id's screws.

Green = throttle positioner screw. Remove & discard
Black = hi-idle screw. Adjust so idle speed goes up to around 1800RPm w/ choke knob pulled on warm engine.
Red = idle speed screw. Set to user preference, usu in the 500-700RPM range when warm.
Yellow= idle mix screw. Set 4 turns out for inital running, then screw in til RPM starts to drop, then back out til idle reaches highest speed.

 

[JohnJL]

I've seen FJ40Jim recommend discarding the TP screw if desmogged. Here's a thread with pics where Jim id's screws.

Hi, and thanks for that link. Here is a picture of his linkage with the circled screws.

Here is are pictures of mine...


I dont seem to have his red-circled screw described as "red idle speed screw" in the same orienttion. Mine point upwards in an impossible-to-get-at flat screw. The linkage and vacuum can obstruct any straight shot at the screw. I had to cut apart and alter a screwdriver to get to the screw. I wonder if I put it back together wrong? Anyway the linkage seems to operate as expected now...Will give it a shot.

 

[thebigredrocker]

On the hard to reach screw. If you lift the "high speed valve" weight, you should have almost a straight shot. If not, perhaps your choke pull off canister got bent down a bit.

I see a double ring booster in the secondary. Do you have a double or single in the primary side?

 

[thebigredrocker]

Your primary side booster looks wet. Is it possible a chunk of hose rubber migrated into the idle circuit?

 

[JohnJL]

I see a double ring booster in the secondary. Do you have a double or single in the primary side?

Your primary side booster looks wet. Is it possible a chunk of hose rubber migrated into the idle circuit?

It is also a double in the primary. Yes, the primary is wet after attempts to start. Would dirt in the idle circuit make it dribble fuel?

The truck now fires on the button when I hit "Start" but coughs and dies. I tried a variety of choke positions. I tried a variety of no - to - 1.5 turns in on the idle screw and 4 to 5 turns out on the air mixture screw. Plugs smell a little gassy but arent fouling like before. Batteries 100%.

So what is the proper sequence for troubleshooting? No idle throttle screw then try more gradually? Air mix at 4 then in gradually?

Thanks!

 

[Dizzy]

Double ring booster = nozzle, or venturi. Most carbs have a single ring on the secondary. The choke fast idle will set the idle speed at cold even if the choke is partly open.