Pre-HE Pertronix Installation with trigger board

Hi All,

I’m Zack and I’ve been lurking around here for a bit now mostly finding myself at the site over and over again via google searches as I work through some issues on a newly had 1977 XJ-S (pre H.E.) in decent condition that’d been sitting in a garage since 1995. I wanted to share the following as I suspect it may be very helpful to someone down the road as I couldn’t find any information on the topic.

This is specifically relating to the use of a aftermarket ignition system on a Pre-HE engine that uses a fuel injection pickup in the distributor.

Here we go:
After spending some serious time fiddling with the OPUS system in the car and subsequently rebuilding the resistor pack, I found the amplifier just wasn’t doing it anymore. The transistor was toasted.

Not looking to repair the OPUS, not loving the cost of the new system from SNG and afraid of future availability of the crane system, I found the Pertronix ignitor II system which was particularly appealing as it’s just so simple. The problem here is that Pertronix says on their website that it’s not for cars with the fuel injection trigger board in the distributor such as mine.

Well, I couldn’t get a straight answer from anywhere on WHY this was the case, I called Pertronix and they didn’t seem to know and searched the web to no avail.

So, I ordered the Ignitor II, (9LU-1122A) and a .6 Ohm coil to match.

Well, it finally came in yesterday and I’m happy to report that with some timing adjustments, the car is now running again.

Why and how:
It turns out that Pertronix demands the position sensor be mounted OVER the vacuum module arm; This just doesn’t do as it will interfere with the fuel injection trigger board. So, I positioned the sensor a little bit different than instructed and much closer to the factory position (but not quite the same).

Then, I made a little eyeball timing adjustment to accommodate.

Next, we’ve the reluctor wheel which is calibrated to THEIR position for the pickup. NOT where I’ve mounted the pickup. Consequently, the points on this wheel are not in the same position as the factory Lucas reluctor relative to the keyway on the shaft.

Another eyeball timing adjustment made to compensate.

Finally, It all came back together and after a little throttle coaxing, the XJ-S came back to life.

The Ugly:
The Pertronix system uses a pickup mounted on a metal plate that’s mounted on a plastic bracket that’s spring loaded onto the distributor. This plastic bracket is NOT snug like the factory pickup bracket. there’s about 3/32" of play to either side. Fortunately, even if it moves around, it still clears the reluctor. The pertronix coil is larger than the factory coil, a new mounting bracket must be had.

Conclusion:
I’ve still some work to do in the way of timing adjustments before I feel comfortable giving a definitive “this can work” answer but I’m happy to say, there may be a solution for a toasted OPUS that’s less than $700.00 and doesn’t involve searching high and low for dead stock crane systems.
I haven’t even started tinkering with the tachometer yet but I can’t see why this won’t work with a resistor in the path.

Here’s a picture of the new system. The white wire grounds to the engine, the black and red to the coil. That’s it. No amplifier.

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Why did you choose this model over the 9LU-1121A?

Hi,

I ended up with the 9LU-1122A as it’s what’s listed from Pertronix as correct for the distributor I have (36DE12)https://pertronix.com/electronic-ignition-conversions?year=1977&make=Jaguar&model=XJ12,%20XJS,%20E-Type#auto

It seems as though the 9LU-1121A is made for a later model, H.E. distributor- It says 82’-84’ in the applications at your link. I’m not sure what the H.E. distributors look like in that date range, but the picture of the unit shows a different aluminum mounting plate.

On a slightly different note:
I had some concerns about interference, magnetically speaking between the units as the trigger wheel changed size but I’m not seeing anything to tell me that’s the case yet. Shielding will be in order if it comes up.

That makes sense. Looking at the photos of the parts, though, it appears that the 9LU-1121A is designed to mount onto the vacuum advance plate, while the 9LU-1122A is designed to replace the vacuum advance plate. In hindsight, do you think maybe the 9LU-1121A might have worked better for what you were doing? Presumably the disk and the pickup are the same, it’s only the mounting hardware that’s different.

BTW, I think I understand why you couldn’t install as instructed. However, the mounting plate attaches to the plastic support with 3 screws, so the first thing I’d try would be to rotate the assembly 120 degrees and screw it down at a different orientation. Being a V12, that should have made no difference to the timing.

I see what you’re getting at with the “1121A” model.

The Disk and pickup are certainly the same for all V 12. The pickup is probably the same for all the Ignitor II systems.

Problem is, I can’t see how it would mount on the factory vacuum module (A.K.A. pickup arm) It’s not so much a plate on here as it is a molded piece of plastic. - Here’s a picture of the original scheme sans reluctor:

You wouldn’t happen to have a picture of the vacuum advance plate from a 1982-84, would you? that may help us understand the difference.

Regarding the mounting position-
You’re completely correct. I never ran the math but now that you mention it, the numbers work; Rotating 120 degrees would work on a 12 Cylinder as the “points” are all 30 degrees separated- The reluctor doesn’t care what cylinder it’s firing.

360 Degrees / 12 Cylinders= 30 Degrees apart.
120 degrees of rotation / 30 degrees = 4 positions of movement.
End result- No change, assuming the timing is evenly spaced, and I can’t see why it wouldn’t be.

I should probably start there when adjusting timing back home.

For posterity- A picture of the factory wheel and the Pertronix wheel, both on the shaft showing orienting position- not terribly useful as the pick-up arm is different, but interesting.
The purple marks are from me making notes.

The 1122A wouldn’t, but the 1121A might. Take a look at the parts in that kit.

Looked at the 1121 again and I don’t think it’s the way to go with the OPUS pickup and Reluctor that was used in my vehicle (see above for pictures).

Perhaps some later distributors are different and it would work in that application.

I do now have the vehicle reliably starting and running. To get it there I needed to static time the vehicle with the old pickup and reluctor using instructions on Mr. Sowell’s site here-

http://www.efsowell.us/ed/jag/engine/distributor/overhaul/DistributorOverhaul.htm
Once I had it set, I took off the old parts and replaced with new again.

In the end-
I’m comfortable confirming that the 9LU-1122A kit and matches coil works on my 1977 XJ-S pre HE with a fuel injection trigger board in the distributor by mounting the pickup 120 degrees from the specified mounting position (closest to the original pickup position)

I hope someone is saved their OPUS frustration.

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