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Discussion Starter #1 (Edited)
If anyone has seen my thread on my project, they already know I'm crazy. So lets take this to the next level of crazy.

Owners of Spica injected cars already understand the problem with the thermostatic actuators and the costs. My question is why?

This is why.




This spring below the thermostatic actuator is designed to force the system into a cold start enrichment state as the engine cools down. It forces the pin of the TA to push back in as the fluid of the TA cools and condenses. This means the system was designed so that its natural state is enriched. If the TA fails, this is the state your spica is defaulted to.

The PO of my car had someone work on the spica that must have had some knowledge of the system, but their solution was imperfect. My spica had the business end of a sure-start cable installed, but no cable. They used a jam nut to force the spica into a normal running state, but no option for cold start enrichment.



Since these cables are no longer being produced, I have the benefit of having the useful end, I just needed to find a generic choke cable to attach to it and route to the dash. But the spring in the spica unit still produces enough force to make actuating the cable difficult and unreliable. The original sure-start cable had a spring that produced a counter force to the one inside the spica.



Trying to find a replacement spring with the correct length and force is proving difficult.

So I am thinking why would I want my spica' default state to be cold start enriched in the first place? If I am going to use a manual option like the sure-start cable, why not change the spica so it doesn't have a default state. No thermostatic actuator, no default state means no spring.



I loosened the nut at the top of the vertical brace, and the screw at the bottom of the brace just enough to free the lever from the notch in the shaft the spring was on. This allowed me to feed the shaft up out through the TA chamber and remove the spring. This allows the lever to move up and down freely, hence no default state. Now I just need to find a machinist that can attach the shaft of the sure start cable to the shaft inside the spica so they are directly connected and move together with the new cable for the sure-start device. This should allow the cable to move freely with only the resistance within the length of the cable itself. When pushed in it will be a normal running state, when pulled out it will be cold start enriched, much like a typical manual choke.

Removing parts from inside your spica. I know! Crazy!

This post is just FYI. I am not ready yet to reattach the fuel system and test the engine so I have no conclusions at this time. I will let you all know what happens. Please respond with comments if you have any ideas but at this time I plan on fully developing this solution, so negativity will fall on deaf ears.
 

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Bosch KE-Jetronic fails the same way - default rich. In their case they knew that rich would not cause detonation.
 

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Discussion Starter #4
I'm not questioning the functionality of the shankle sure-start. My unit is missing the spring which pushes back against the injector pump, which is what makes actuating the shankle difficult. Instead of trying to find a replacement spring, and hoping it is in good condition, not worn out, or not being able to find a new spring of the correct length or force, I hoped that removing the spring from inside the pump would allow me to develop a solution that would not have to overcome any force.

Other forum posts have suggested that the requirement to change from an enriched state to a lean state is due to American regulations. The euro spicas could have manual chokes since they did not have to adhere to american emission standards. If we are removing the thermostatic actuator and going with a manual shankle cable, we are already bypassing standards, so why keep the inner spring if its only purpose is to interact with a thermostatic actuator, which we have already removed from the system. I am trying to understand the system, and what effects our changes have on functionality. If we remove one part, and it negates another part, why not remove that also?

The euro choke cables don't look like they would interface with the actuator port on the american spicas, different mounting types.

I have also seen some posts regarding an electric actuator replacement. I have considered some type of servo with a screw drive to actuate the lever, but the force of the spring is going to be a factor when finding a strong enough servo. If you eliminate the spring, the servo would have zero resistance to moving the lever inside the spica. Perhaps someone with some arduino skills could program something that reads the temp from the sending unit, translate that to turn the servo and actuate the enrichment proportionally with the temp.
 

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I'm sorry, I misunderstood this statement:

But the spring in the spica unit still produces enough force to make actuating the cable difficult and unreliable.
Actuating the Sure Start requires pulling on the cable. The spring in the Sure Start will provide resistance to that pulling. The missing spring would make it much easier.

I would think that a replacement spring that has more compressional resistance (Is that a real term?) would be sufficient. If you have a spare pump, why not try that same spring in the Sure Start?
 

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I bought mine a few years ago and the design was changed per the picture. It will be interesting to see how a new style TA replacement turns out.

I thought Brad at Alfa Ricambi was still selling Sur-Starts. But, then, maybe not?
 

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the one thing to be aware of is if there is any additional force placed on the rod from the follower, when the pump is spinning. I don't know the pump well enough to comment on that.

Rich if no one needs the Surestart I can certainly use it. I gave my spare to Chase for his Super project, and now I find I.'m in need of one!

cheers bob
 

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Discussion Starter #11
Thanks for the offer GP. I think I am good for now.

I might have over come another issue. I need to keep the ability to adjust the pump gap as well as have the two shafts linked together.

Here are my parts atm.



The spring loaded screw fits inside the shaft from the spica and is used to adjust the pump gap.

I found a replacement screw at the local hardware store so that I can retain the original screw.



I spoke with my local welding shop and they feel they can weld the screw(heliarc ? (sp)) to the shaft of the shankle device.



I can then thread the shankle with attached screw back into the spica shaft. This will directly connect the two while allowing me to spin the shankle, turning the screw with it, to adjust the pump gap.



The outer casing of the shankle, which the shankle shaft fits into, does spin freely of the mounting plate which should allow me infinite adjustment within the length of the screw. It shouldn't be much different that stock other than I will be able to spin the adjustment screw without removing the shankle. I would just need to loosen the mounting screws enough to allow the outer shaft to be spun.
 

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Discussion Starter #12
I'm sorry, I misunderstood this statement:



Actuating the Sure Start requires pulling on the cable. The spring in the Sure Start will provide resistance to that pulling. The missing spring would make it much easier.

I would think that a replacement spring that has more compressional resistance (Is that a real term?) would be sufficient. If you have a spare pump, why not try that same spring in the Sure Start?
The length of the spring inside the spica is twice the length of the shankle. I could try cutting a spica spring down to the correct length but getting the length and force just right through cutting could require multiple springs. One cut too short and you need to start over. I did find some springs at the local hardware store that fit the shaft pretty well, but their force wasn't quite right, even using two and then cutting one short to have it still be difficult to get the shankle to stay put. The original spring in the shankle must have been specifically designed i'm sure.
 

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Discussion Starter #13
the one thing to be aware of is if there is any additional force placed on the rod from the follower, when the pump is spinning. I don't know the pump well enough to comment on that.

Rich if no one needs the Surestart I can certainly use it. I gave my spare to Chase for his Super project, and now I find I.'m in need of one!

cheers bob
Between what I'm trying to do and what GP is doing, you might not need to find a sure start.

If removing the spring from inside the spica to zero out the force works, owners might be able to fabricate their own mounting plate, or use a scavenged one from a broken TA, to build their own shaft that would interact with a generic choke cable.

It has been nice using the Shankles manufactured part, but making a tube that would receive a choke cable might not be too difficult. The volumetric bulb of a broken TA might even suffice. I haven't opened up a TA but the inner pin might somehow be usable also, just eliminate the fluid and connect it to a manual choke cable.
 

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Discussion Starter #15
Have you thought of looking here for springs? Perhaps they have something. I bought spring stock from them when the barometric compensater spring broke on my Spica pump. Worked out just fine.

https://www.mcmaster.com/springs
Thanks for the link. That is a great option if this idea of no springs means less force to actuate the cable doesn't work out.
 

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I have also seen some posts regarding an electric actuator replacement. I have considered some type of servo with a screw drive to actuate the lever, but the force of the spring is going to be a factor when finding a strong enough servo. If you eliminate the spring, the servo would have zero resistance to moving the lever inside the spica.
To this point: I made a plate with a 6mm nut welded to the center. The plate replaces my broken TA. A long 6mm screw extends the correct distance into the SPICA, it is stopped by a nyloc nut. At the top of the long screw is a wing nut to make it easier to rotate with finger tips. The force required to turn the screw is minimal, I do it with fingertips as I reach around the air filter canister and blindly rotate the screw out 3 rotations for my "cold start", then after a minute I climb back out of the car to rotate the screw inwards 3 revolutions till it hits the nyloc nut stop for normal running.
Could a speedo cable be able to rotate this nut?? then a simple "choke setup could be fashioned inside the car for easy operation. I have a Shankle Sure Start but found it a hassle operating it so it is removed.
The screw gives "mechanical advantage", yes, that's right mechanical advantage. Darn, why couldn't I remember that 35 years ago at Cal Poly??!!
 

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one could envision a lever arm that exits the cover, with a round boot to seal it, providing a mechanical advantage if some smaller spring force might be useful to maintain position.

The utility of a lever arm and a spring return force would allow a simple cable drive to a motor. Really this whole thing screams out for a O2 sensor in the collector, driving a feedback system to adjust the position of the pin thereby keeping the mixture in the sweet spot. Wish I was retired and then I would do it......
 

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one could envision a lever arm that exits the cover, with a round boot to seal it, providing a mechanical advantage if some smaller spring force might be useful to maintain position.

The utility of a lever arm and a spring return force would allow a simple cable drive to a motor. Really this whole thing screams out for a O2 sensor in the collector, driving a feedback system to adjust the position of the pin thereby keeping the mixture in the sweet spot. Wish I was retired and then I would do it......
Yup. Update the logic section of the pump to utilize more current technology for mixture control. I suspect many of us have thought (dreamed?) about that prospect. I know that I have. I'm also still working or...
 

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If you’re still considering a spring I believe I can point you in the correct direction. You’ll need the following data: outside dia, inside dia, relaxed length, compressed length.
 

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one could envision a lever arm that exits the cover, with a round boot to seal it, providing a mechanical advantage if some smaller spring force might be useful to maintain position.

The utility of a lever arm and a spring return force would allow a simple cable drive to a motor. Really this whole thing screams out for a O2 sensor in the collector, driving a feedback system to adjust the position of the pin thereby keeping the mixture in the sweet spot. Wish I was retired and then I would do it......
Yup. Update the logic section of the pump to utilize more current technology for mixture control. I suspect many of us have thought (dreamed?) about that prospect. I know that I have. I'm also still working or...
Already been done - it's called Megasquirt 😉😉.
 
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