Retrofit 24x reluctor to early V8

[Jim Blackwood]

Thanks for posting that. Hard to argue against an actual scope trace. However as I said, the actual pulse train is a secondary concern. The primary and original question remains:

How did you verify that the zero reference hole actually lines up with the pickup when the crank is at TDC?

A reference line on a trace is just that, a reference line. Unless you have some way to generate a trigger from that line and then use it to trigger a timing light, and then use that timing light to flash on the damper or degree wheel and let you confirm that the timing mark lines up with the zero, then you haven't proven anything. Or it could be done by marking the tone wheel as I said before.

Has anyone done either of those things? Without that it is impossible to set up the external sensor position.

Jim

[dave w]

Attached is the data I have from my "Google Research" or "Personal Research".

dave w

[kur4o]

Forget about timing light tune up. What you need to do is mount the sensor to your preferred location. Bring the engine at #1 TDC. Rotate the wheel till the #1 tdc mark on the wheel is aligned with the sensor. Than you have your starting position for the wheel and very small adjustments will be needed from there.
Did you thought about the cam sensor. It must be aligned with crank too.

[Jim Blackwood]

As much as I appreciate the suggestions, you are avoiding the question.

Until this sensor/tone ring alignment question is answered it's nothing but recycling old web info that isn't on point. Simply assuming that the sensor lines up with the zero reference hole at TDC just isn't enough. Maybe it does, but maybe it doesn't. So far I have not heard from anyone who can actually confirm that it does. Based on my own testing results I'm inclined to think that maybe it does not, but again that is not definitive because failure to achieve an expected result does not disprove the existence of a relationship.

So, we are still at square one. Just so you know, I did align the sensor with the reference hole and there was no spark. This could be from other causes but the first step is to eliminate the obvious. Make sure the sensor is aligned properly so the ECM gets the right signal. At this point it is still not possible to do that.

Perchance in the next few weeks I can visit my machinist and he might have a LS block and crank and be willing to let me visually confirm the relationship. A few moments with a sharpie are all that are required. However, that again delays the operation. I was hoping someone here might be able to help.

Jim

[kur4o]

Make a drawing what exact measurements you need and I will try to get them in a day or two.

[kur4o]

I did align the sensor with the reference hole and there was no spark.

If the pcm gets the signal from the crank sensor, you will get spark but it will be at the wrong time. What is the distance from top of the sensor to the wheel. It must be really close. I have seen scored sensors by the wheel. Monitoring the pcm for rpm signal will show if it gets the signal. Troubleshooting the problem with timing light will not work. Get some logging device and monitor the PCM. If it sees rpm than you are good, if not the problem is within the sensor position.

[Jim Blackwood]

Good suggestions but one step at a time is best I think. I will measure the sensor gap tomorrow. It's pretty close but I can close it up further if needed.

I agree with your thought that out of phase timing should not result in no spark. But as you say, a lack of a proper sensor signal would. I should be able to put a scope on the sensor and at least get a pulse train while cranking. Provided that looks usable I can move on to the low level coil output trigger signals. Those should be there as well.

As for a drawing as you asked, Here is how I propose to check the tone wheel and sensor alignment. It requires a block and crank with the pan off:

1) remove the CKS from the side of the block
2) rotate the crank to the zero timing mark, TDC
3) using a sharpie, mark the edge of the tone wheel by going in through the sensor hole in the block. This may require a shot of carb cleaner and an air blast first.
4) rotate the crank so that the timing hole is visible (pan removed)
5) locate the sharpie mark and note it's location relative to the timing mark. The accuracy with which the mark is made will affect this result.

That's it. A simple matter if a block is available, and it puts this discussion to bed. Once we know that is right I can get serious about the rest of the troubleshooting process. But for the sake of anyone working up a crank trigger for the 0411 controller this needs to be a known quantity. I actually hope it turns out to be zero as that means I have it right. But I really do have to know for sure.

Jim

[lionelhutz]

I'll suggest it again. Try the forward/backwards alignment of the sensor. The 24X sensor and wheel is a dual track system. The sensor reads each half of the wheel as a separate track. Hence, it must be aligned forwards/backwards correctly. Sensor rotation and direction are very important too.

The documents and the posted scope waveform provide more than enough info to get the sensor aligned with the wheel at TDC correctly.

[lionelhutz]

Post a picture if you can too.

[lionelhutz]

No spark at all means you've got something else wrong.

Match the pulses on the diagram to the notches in the wheel and you will find that the alignment hole matches with the TDC #1 pulse which means that is the TDC #1 position on the wheel. So, that's where the sensor MUST be when the #1 piston is also at TDC.

The scope traces also confirm that's exactly how it works because the cam signal switches at the same time the crank sensor picks up the #1 TDC notch beside the alignment hole. The alignment hole and corresponding notch must be passing in front of the sensor at #1 TDC for the sensor to be capable of picking it up.

When you hold a LS1 crank so the alignment hole is to the right, the #1 crank throw is facing where it'd be at TDC.

The crank sensor goes into the block with the plug facing forwards.

Tons of people have done this before and got it to work without the need to pursue the question you are so concerned about.

Centering the sensor at the alignment hole is plenty close enough to get your engine running. If you need it to be exactly accurate then tune it with no spark advance and fine adjust the crank sensor to get the spark at exactly TDC. That's assuming your crank sensor bracket is very solid yet has some adjustment and you also have TDC marked on the balancer with a pointer that has been verified with a piston stop.

Assuming you have the sensor clearance minimized, I would try moving the sensor forwards or backwards a little with respect to the wheel.

[dave w]

Forget about timing light tune up. What you need to do is mount the sensor to your preferred location. Bring the engine at #1 TDC. Rotate the wheel till the #1 tdc mark on the wheel is aligned with the sensor. Than you have your starting position for the wheel and very small adjustments will be needed from there.
Did you thought about the cam sensor. It must be aligned with crank too.

Good point on the Cam / Crank Alignment. My own personal research showed the 24x Cam / Crank Alignment is less sensitive than the 4x '0411 low resolution system. Pic below is from my R&D development of a low resolution dual trigger '0411 distributor (based on the L31 engine). The reason for 8 teeth on the dual trigger distributor is because 2 crank rotations = 1 cam rotation. Theoretically, a dual trigger distributor with 48x crank trigger to 1x cam trigger would provide coil on plug capability. Theoretically, a Large Cap HEI distributor diameter is needed to provide enough resolution for the 48x trigger wheel, pic below. I use CREO Elements Direct https://www.ptc.com/en/products/cad/...irect/modeling for my CAD drawings.

I think it's possible to CAD a Coil-On-Plug dual trigger distributor for virtually any domestic V8 engine manufactured after 1955 that used a distributor. Once the CAD is complete the CNC machine will do the rest of the work. Would it be practical .... that depends on the Budget. Would it be cool .... likely the answer is Yes

My 48x dual trigger distributor design would be based on the very successful aftermarket trigger wheel.

dave w

CIMG2743.jpg

144mm_Crank_Trigger_Wheel_48X.JPG