Because winter's coming and (and there's no forum for other idi fords)

[Booyah45828]

It's that it vent's the housing pressure so that transfer pressure more easily pushes the advance piston. So I don't think we have a mechanical advance. You crank, it builds pressure, and advances the piston. Does it get a few degrees advance and how far into cranking?

My experience is the few degrees of advance makes a huge difference cold starting.

IDK how the pump exactly does it, maybe @Thewespaul can chime in with the specifics. I really don't care how it does it, so long as it does do it.

If it works based off housing pressure, you likely will have very little when cranking, which isn't a bad thing because you want the timing to be retarded while cranking.

Like I said in the post before, you want the injector to fire at TDC when cranking so that the heat in the chamber is at it's max. That's something I was taught in school. So the cold timing advance having no effect while cranking is perfectly fine in my eyes.

 

[nelstomlinson]

Getting back to Vern's need to start in the cold, a heat patch on the oil pan, a trickle charger on the battery and the block heater will be plenty for him as long as he can plug it in. Out in the field, a Webasto is unbeatable. A little spark ignition generator that starts in the cold would let him plug in in the field.

Vern is far enough south that he's never going to get extreme cold.

Edited to add:
I used to have a propane fired tank type engine heater on a pickup with a gas engine. Propane will work great down close to -40. That's probably colder than your coldest daytime highs, Vern, and the propane heater was a lot cheaper than the Webastos and Espars.

 

[Vern]

you want the injector to fire at TDC when cranking

Really? Don't we want the heat of combustion to compound with heat of the air/fuel from the swirl chamber. Isn't that why there are advance mechanisms to aid in cold starting, to allow for better heat build up?

propane fired tank type engine heater

That is exactly what I want. I am inquiring about whether a relatively simple mechanism that advances the timing would offer an improvement over the original equipment in smoothness, smoke and wear and tear.

I tell ya, the addition of a mechanical advance cold start lever from an old VW to a Delica 4d56 intended for the warmer climate over-seas and equipped only with a hydraulic venting sure makes an improvement after the thing sat at an airport parking lot unsupported for 14days, well below freezing.

 

[Booyah45828]

Really? Don't we want the heat of combustion to compound with heat of the air/fuel from the swirl chamber. Isn't that why there are advance mechanisms to aid in cold starting, to allow for better heat build up?

When cranking, you want the heat of compression to compound with the air/fuel to start combustion. The heat of compression will be at it's highest at TDC, so that's where you want injection to occur at while cranking. Doing that gives you the highest probability of lighting off while cold.

Once started and running, the cold advance mechanism will kick in and advance the timing. While running, advanced timing will put more heat into the engine and chamber.

This was all gone over and explained in this thread here. https://www.oilburners.net/threads/super-duty-visor-advice-on-cold-start.85080/

 

[Vern]

your cranking fuel will not change on the test stand whether it’s full throttle or idle, the cranking rpm will affect it more.

Had you obvserved if return fuel volume changed?

I’d like to do some timing readings with the engine cranking over and see how much the timing changes with throttle change.

I'm curious to know of you what this would reveal as well.

When cranking, you want the heat of compression to compound with the air/fuel to start combustion. The heat of compression will be at it's highest at TDC, so that's where you want injection to occur at while cranking. Doing that gives you the highest probability of lighting off while cold.

Once started and running, the cold advance mechanism will kick in and advance the timing. While running, advanced timing will put more heat into the engine and chamber.

This was all gone over and explained in this thread here.

Is it reliable information? Does it not kick in during cranking when transfer pressure builds?
"The heat of compression will be at it's highest at TDC.." And then cooling down all the sooner while exhausted, perhaps. I think the impetus behind the Ranger instructions to advance the timing and then fire is the retention of heat. how effectively is it propelled forward. Hysteresis.

And I have noticed how much more quietly and smoothly my 7.3 runs while running retarded, warm. Not so much starting. I wonder what would happen if we pushed our properly timed pump's light load advance lever in and tried starting cold. And if you could push the piston from the other direction what the difference would be. Would it make for greater reliability?

 

[Thewespaul]

Yes we have a mechanical advance, it’s the arm on the side of the pump actuated by the face cam on the throttle shaft. Return is almost nothing at cranking, timing will change with throttle position even at cranking, I see this first hand daily running the stand. Engine will start about the same regardless where the piston is at, what’s more important is transfer pressure and volume of fuel the head can support at the lower speeds.

 

[Vern]

timing will change with throttle position even at cranking

You mean the light load advance, right? The one that acts on the housing pressure side by spring? And doesn’t actually have a way to pull the piston in the advance direction? That is a mechanical advance in my mind. Many refer to the lla as the retarder.
From what you say I advance timing with the advance of the light load lever. does it advance with the pressure from the transfer pressure while cranking please.

 

[Thewespaul]

You mean the light load advance, right? The one that acts on the housing pressure side by spring? And doesn’t actually have a way to pull the piston in the advance direction? That is a mechanical advance in my mind. Many refer to the lla as the retarder.
From what you say I advance timing with the advance of the light load lever. does it advance with the pressure from the transfer pressure while cranking please.

Let me back and explain that further, lets establish a few things.

-Housing pressure being zero advances the pump. How? Housing pressure and transfer pressure are basically acting against each other. When you have a worn out pump that wont hot start that is because the tolerances in the head or advance piston do not allow the pump to build proper transfer pressure when at cranking speed, typically need at least 20 psi of transfer pressure at cranking.

-The advance piston moves in the retarded direction. The pump will always be in the fully advanced position when cranking unless the throttle is at wide open, then the servo spring has enough tension to overcome the transfer pressure and will slide the piston over to the retarded side. But there's more going on with our advance system than just the piston's position that determines the timing. The hydraulic portion works with the mechanical advance via the light load advance servo, which basically acts as a shutoff valve for the internal transfer pressure bypass, basically it "boosts" transfer pressure in the wot position by eliminating a bypass, but really only affects timing at running rpms where the difference in transfer pressure to housing and inlet pressure is much greater, but this boost effect is a mechanical means of advancing the timing by means of increasing transfer pressure. The benefit of this feature is better performance at wot, smoother throttle operation, quieter operation at light loads and better mileage at light loads (highway).

I can operate just the throttle with no pump rotation but just 5 psi inlet pressure to return the piston to the advanced position and see timing movement with the throttle actuation, same with it at cranking speeds. The transfer pressure side is your return spring and the lla side is the mechanical actuator.

 

[IDIBRONCO]

Let me back and explain that further, lets establish a few things.

-Housing pressure being zero advances the pump. How? Housing pressure and transfer pressure are basically acting against each other. When you have a worn out pump that wont hot start that is because the tolerances in the head or advance piston do not allow the pump to build proper transfer pressure when at cranking speed, typically need at least 20 psi of transfer pressure at cranking.

-The advance piston moves in the retarded direction. The pump will always be in the fully advanced position when cranking unless the throttle is at wide open, then the servo spring has enough tension to overcome the transfer pressure and will slide the piston over to the retarded side. But there's more going on with our advance system than just the piston's position that determines the timing. The hydraulic portion works with the mechanical advance via the light load advance servo, which basically acts as a shutoff valve for the internal transfer pressure bypass, basically it "boosts" transfer pressure in the wot position by eliminating a bypass, but really only affects timing at running rpms where the difference in transfer pressure to housing and inlet pressure is much greater, but this boost effect is a mechanical means of advancing the timing by means of increasing transfer pressure. The benefit of this feature is better performance at wot, smoother throttle operation, quieter operation at light loads and better mileage at light loads (highway).

I can operate just the throttle with no pump rotation but just 5 psi inlet pressure to return the piston to the advanced position and see timing movement with the throttle actuation, same with it at cranking speeds. The transfer pressure side is your return spring and the lla side is the mechanical actuator.

Ok. That's it. The next time I'm down your way, you're going to have to show me some of this stuff so I can understand it better (hopefully).

 

[Diesel D]

in terms of winter starting, have you considered keeping the vehicle in a garage?

 

[nelstomlinson]

in terms of winter starting, have you considered keeping the vehicle in a garage?

Wait - the vehicle goes in the garage? Who ever heard of such a thing?!?!?!

 

[IDIBRONCO]

Wait - the vehicle goes in the garage? Who ever heard of such a thing?!?!?!

Not me!

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[Philip1]

Wait... the truck is supposed to leave the garage? Lol

 

[IDIBRONCO]

Mine does.

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[Vern]

The advance piston moves in the retarded direction. The pump will always be in the fully advanced position when cranking unless the throttle is at wide open

@Thewespaul you mean spring pressure holds the advance piston in the advanced position at rest and not pressurized?

The power side of the advance piston is the side of the pump opposite the LLA lever and servo valve/spring, correct? Transfer pressure pushes the advance piston in the direction of the lla lever and servo/spring IF flow is permitted by the servo piston by its position in relation to the passage supplying transfer pressure to the power side of the piston. Retarding it?

Non lla equipped ip advance function is a relatively simple spring acting against the advance piston. Someone tell me point blank that essentially the lla servo spring is doing the same general thing, along with the valve do-hickey and movement of spring.

This shows a roosa master with spring pressure holding the piston in the retarded direction. Is that also how the truck db2 with the lla are designed?

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5 psi delivered to the inlet allows the advance piston into the fully advanced position why? hydraulic pressure on the power side in the absence of rotational force to act against it overcomes spring tension. it will adjust by the accelerator's action on the servo valve relieving and restoring those 5psi but also changing advance piston return spring trim. Correct?

because during rotation the timer piston is forced by the plunger action in the retarded direction during rotation, the scenario (the one we're up against) changes. If the purpose of the lla is to provide advance during low transfer pressure pump states, may be what is being said by "it moves in the retard direction" is that the spring pulls on the timer piston towards the advance direction and transfer pressure moves it the other direction.

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interesting that I saw mention in the service bulletin this comes from
that some engines require the advance. What would the characteristics of an engine that require it be?

the timer piston is acted on by the transfer pressures which are regulated by the servo valve in reference to its position in its bore against housing pressures. in the event of housing pressures being zero (advance solenoid engaged), transfer pressure more easily moves the advance piston IF the LLA servo position allows it I guess, but it isn't exactly metering the entire supply of transfer pressure to the power piston.

Edited to jump the youtube video to the point and finish a sentence lol