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Discussion Starter #1 (Edited)
Spica micro switch - modern replacement? SOLVED

The micro switch for the decel fuel cutoff solenoid in my '74 Spica pump has given out.

I have taken the pump off before and am prepared to do it again to see if I can repair the switch.

Is there a modern micro switch that I can use as a reasonable replacement? I suspect it needs to be temperature tolerant but don't know if there are other considerations.

I see that Wes sells them for $70 which is a lot more than I'd like to pay unless there really is a good reason...

My motor runs fine even without the decel FCS working, but I don't like the little burbles (never really backfires). Please let me know if you have input on replacing the switch, but don't just tell me not to fix it.
:)
 

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That switch is probably available from electronics supply houses. It's just a microswitch, but it does live in a pretty bad environment, heat, vibration, heat/cool cycles, etc.
 

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Discussion Starter #4
The switch I have from my pump says it is a 5A 250V 83 132.

I'm not certain if that is the original OEM switch, or something that has been replaced along the way. The solder on one of the terminals is terrible which makes me think someone has "repaired" it before...
Switch_01a.jpg

But it has been working until recently, so unless someone can tell me the part number for a more correct switch I'll take a whack at replacing it with a new one of the same type.

Searching around I found these being sold by DigiKey (from whom I've had good luck ordering stuff in the past) and it looks like the specs match:
831320C1.0 Crouzet Switches | 966-1384-ND | DigiKey

Switch_02.jpg

The spec details are on page 11 of the Crouzet data sheet here:
http://www.digikey.com/Web Export/Supplier Content/Crouzet_646/PDF/crouzet-catalog-switches.pdf?redirected=1


At $6.32 thats way better than the list price for the (curently backordered) ones from Centerline or Wes... I ordered a few and they should get here soon. I'll let you guys know how it goes.
 

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Looks like a good replacement to me. 34 years of electronics. The part will certainly handle the function.
 

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Discussion Starter #8
Success!!!

The switches came today. Testing them on the bench, the action is great - very tight and completely reliable with my meter. The numbering of the terminals is different than the old one but the function is the same. The top ones are the ones to use as they are normally open and connect when the switch is depressed.

IMG_5726.jpg

I clipped the bottom two terminals off since they are not used and the old one also had them removed. I soldered the leads onto the new switch and installed it in the holder/assembly that mounts it on the pump.

The SPICA Overhaul and Calibration manual has clear instructions on how to adjust the switch. I used a 1mm feeler gauge and adjusted the screw to just turn on and confirmed that it always turned off in the rest position.

As a bonus I wired together a relay to turn on the dashboard light usually used by the secondary oil pressure sensor (sending it to ground when the lead to the FCS is energized). That let me confirm right away once everything was back together that it was working. And then test driving it around the light came on every time I expected it would and never when I didn't. It works GREAT!

I won't leave the dashboard light that way for long but its awesome to see exactly when the FCS is engaged.

We will just have to wait and see if the new switch holds up to the heat, vibration and general rough environment in the pump long term, but I'm pretty optimistic. They seem like they are identical to the old switch I took out but nice and new.

Obviously the biggest pain of the whole ordeal is pulling and replacing the SPICA pump. I've done it three times now (in the ~25 years I've owned the car) and this time I actually felt like it wasn't that bad. A stubby 13mm wrench is key for getting the base nuts that hold the pump and everything else just comes down to being patient and methodical.

For just over six dollars, the new switch seems like a bargain and I'm really happy to have the system working properly again - no burbles!

Kris

Screen Shot 2015-09-17 at 8.30.57 PM.jpg
 

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It looks like the OLD Switch had 3 and 1 Soldered together as well as 2 and 4. Is this so? Maybe the picture is fooling me?
 

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A slightly easier way to remove the pump is to remove the six nuts holding the pump to the base. You do have to loosen the stays on the fuel pipes and move them back a bit to pull the pump up to clear the short studs.

All in all, removing it by the base isn't really that bad, just fiddly with that one nut.
 

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Discussion Starter #12
It looks like the OLD Switch had 3 and 1 Soldered together as well as 2 and 4. Is this so? Maybe the picture is fooling me?
Nope. The old switch had the leads soldered to the top two terminals (3 & 4). The bottom two were clipped off. If it looks like they were connected, it is just an issue with the photo.

The new switch has the terminals numbered differently (1 & 2) are at the top, and they are the ones to use.


A slightly easier way to remove the pump is to remove the six nuts holding the pump to the base. You do have to loosen the stays on the fuel pipes and move them back a bit to pull the pump up to clear the short studs.
I did that the very first time I took the pump out. After that the last two times I've gone for the base. Without a stubby 13mm I can't see how it would be possible to get up under the pulley to get that upper right nut. Either way does work and depending on the tools you have available and how easily things come apart there may be obvious advantages in one approach or the other.
 

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A stubby wrench or not a stubby wrench?

........................

I did that the very first time I took the pump out. After that the last two times I've gone for the base. Without a stubby 13mm I can't see how it would be possible to get up under the pulley to get that upper right nut. Either way does work and depending on the tools you have available and how easily things come apart there may be obvious advantages in one approach or the other.
Years ago the first time that I need to remove a Spica pump (74 Spider) I took a regular (non-stubby) wrench and ground down the box end so it would clear the tightest place near any of the 4 nuts holding the base of the pump to the engine block. I then took a torch and made a couple of bends so that it would clear any of the stuff in the way of reaching any of the nuts (dip it in water while still red hot to re-temper it). Worked great. The longer handle gave leverage to loosen the nuts. I still have it and it still works the last time that I need it a few years ago. Just an alternative to a stubby wrench if you need to remove a Spica pump.
Cheers.
 
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