efi A Cam Position Sensor design - please critique

[jimk]

I was thinking of mechanical damage.

[uai]

I still think it's a solution to a non-existing problem. Why not just go simple?
No aftermarket chinese crap but OEM Automotive stuff. 
Stealth as well. And can be used with COP and Dizzy

 

Edited March 7 by uai

[AustrianVespaGuy]

On 3/7/2024 at 4:29 PM, uai said:

I still think it's a solution to a non-existing problem.

Well you're certainly not wrong, it's totally unnecessary and using some sort of distributor-based trigger is certainly easier. I just REALLY like the cleverness of repurposing the now-vestigial fuel pump lobe as it's perfectly suited to this task: signaling just one t per cam revolution!

Edited March 9 by AustrianVespaGuy

[jimk]

To see new solutions appear is always interesting.  As more are developed, the state of the art often advances.  It certainly a cleaner install than what I made using a Honeywell GT101 on a hacked distr.  Keep us informed of your progress.

[uai]

11 hours ago, AustrianVespaGuy said:

Well you're certainly not wrong, it's totally unnecessary and using some sort of distributor-based trigger is certainly easier. I just REALLY like the cleverness of repurposing the now-vestigial fuel pump lobe as it's perfectly suited to this task: signaling just one t per cam revolution!

If there was a proper sensor for this harsh environment it would be a perfect solution

[veronatii]

To avoid the heat issue I could move the sensor out of the head, and use the fuel pump rod as the pickup instead of the cam directly.

 

Something like this.. 

 

 

On 3/7/2024 at 1:29 PM, uai said:

I still think it's a solution to a non-existing problem.

 

You're definitely not wrong, but as AustrianVespaGuy said its fun to innovate.

[Son of Marty]

That looks good, I'm afraid in my mind that the fuel pump lobe has too gentle a profile for a good reading it might work better with a lobe shaped like the valve opening lobes with a sharp lift. just say'n

[tzei]

Bench test... with correct rpm (with some head room).

[veronatii]

I decided that V1 of my fuel lobe cam position sensor wasn't going to work for a couple reasons; first being the sensor's low temperature rating and second being the lack of adjustability. Also if this sensor were to melt/fail it wouldn't be a quick fix.

 

V2 moves the sensor outboard of the cylinder head and uses the fuel pump push rod as the activator. The sensor is threaded into the fuel pump block off plate and therefore can be adjusted and replaced easily. A small spring slides onto the rod between the cylinder head wall & support and will be held in place with a set screw. It's a tight fit but I think it should work.

 

Here's where the spring will fit. I have a stiffer spring on the way with an 8mm ID and should fit nicely. Total rod movement is about 4mm.

 

I had to use some JB weld to fill the v1 hole. I'll probably end up ordering another block off plate so I can start fresh.

 

Top view

 

There's some much shorter m8 sensors (~22mm) that will fit a lot cleaner than this 45mm version. Also I'll be making an aluminum angle spacer here as well.. cleanest would be to weld a spacer directly to the block off and thread the whole thing.. Another option would be to just drill the sensor hole perpendicular to the block off plate even though the fuel pump rod sits about 78°.

 

[popovm]

@veronatii, very cool! That's some quick iterating. 

 

@uai have a link to instructions on how that distributor-based version is built? I assume you need to have a healthy slop-free distributor?

Edited March 13 by popovm

[uai]

1 hour ago, popovm said:

@uai have a link to instructions on how that distributor-based version is built? I assume you need to have a healthy slop-free distributor?

No, but I built that type twice - once like that (that would require some work to get to the electronics in case of failure, but can still act as distributor. And once whre I omitted the upper part of the shaft so it's only for static ignition. 
Version 1: I drilled an indexing hole through both shafts with the mechanical advance half engaged.
Then removed everything that was left from the machanical advance. Machined a litttle bit out of the distributor and a little bit from the hall sensor so they will fit, removed one of the gates from the hall sensor rotor and pressed it on the top shaft and had two little bolts through the shaft one to keep indexing the rotor, the other to index upper and lower shaft.
Version 2: removed the upper part of the shaft and all parts of the mecanical advance. Machined a little bit fron the hal sensor so it will fit the distributor. Put the Rotor on (this time -3 gates ) on the shaft and then fitted the hall sensor upsidedown from above.
 

[AustrianVespaGuy]

4 hours ago, veronatii said:

Here's where the spring will fit. I have a stiffer spring on the way with an 8mm ID and should fit nicely. Total rod movement is about 4mm.

Looks great, but what does the spring bear against? Are you drilling/tapping into the fuel pump pushrod in order thread the setscrew into the rod?

[veronatii]

2 minutes ago, AustrianVespaGuy said:

Looks great, but what does the spring bear against? Are you drilling/tapping into the fuel pump pushrod in order thread the setscrew into the rod?

 

Yep thats the plan-- drill through the rod and tap a thread.. then maybe add a washer between that and the spring. Originally I wanted to use a collar but there's not enough space.

[Tommy]

7 hours ago, veronatii said:

 

Yep thats the plan-- drill through the rod and tap a thread.. then maybe add a washer between that and the spring. Originally I wanted to use a collar but there's not enough space.

I was earlier thinking this kind of structure. I'm afraid there's not enough space to fit a spring that would fill all the boxes: force, compression distance and lifetime. Two is not a problem, but all three... a problem.

[uai]

More pics