Static ignition tuning

I have a 1972 E Type V12 2+2. I am trying to get it back on the road after resting for 35 years. I have the E Type Operation and Maintenance Handbook. On page 80; gives somewhat instructions as to static tune up. If I am reading correctly, the instructions seem incorrect.
Step 1 Handbook states to line up No 1 mark to central pick up housing. OK.
Step 2 set Vernier control to centre. OK, (my Vernier is gone.)
Step 3 Rotate engine so timing mark lines up with pointer.
1 If done this way why do step one and two? Aligning timing mark will move the No 1 mark?
2 What is the Vernier used for? Mine is apparently broken off, gone. I do see the adj screw is special as it has a hole on the bottom for something and must have been used for ???
3 Do I need the Vernier option?
4 Can I purchase just the bottom of the distributor housing? PN, vendor? Used?

Thanks much for the help. The auto is close being road ready! I am also trying to clean the chrome wires which is another subject.


Initial step is to ensure correct cylinder is on firing stroke; all bets are off if distributor has been removed.

Thank you. I guess that makes sense. (The distributor was not removed) Align the marks puts the engine on the firing stroke, then move the crank to align with the 10 BTDC mark, static. Got it! Now I have to figure out a way to get a timing light in that area to take a reading. Love a challenge.

You might want to know that Roger Bywater devised a revised method of setting the ignition timing on the pre-H.E., setting it at operating speed rather than at idle - much as the H.E. is done, and for the same reason: That’s where it’s important that the timing is correct. I included his method in my book on the XJ-S. I’ll try to copy and paste it here:

"TIMING THE PRE-H.E.: The procedure is described in the ROM, section 86.35.29/7. Basically, you disconnect the vacuum advance, lower the idle to make sure you’re off the bottom of the centrifugal advance curve, and set the timing at 10º BTDC. Much easier than the H.E. procedure!

On the other hand, there’s a very good reason the H.E. went to setting the timing at 3000 RPM instead of at idle. You’re not likely to burn pistons at idle; it is far more important that the timing is correct at highway speeds. The H.E. procedure minimizes the impact of variances in the advance mechanism: If the distributor isn’t quite within tolerances, the timing will still be correct at 3000 and will merely be off at idle instead. Much safer.

So, why don’t we adapt the H.E. timing procedure to the pre-H.E.? Roger Bywater: “What you are saying is absolutely correct and setting the timing at low speed before any advance takes effect is just about the worst way of doing it. In all normal operating conditions the advance could in theory be 4 degrees out yet still be within spec. Allowing for wear and tear, not to mention questionable original build quality, the error could easily be more than that.”

Bywater went on to provide at-speed timing specs for all pre-H.E. V12’s:
Carburetted V12’s 35° BTDC @ 4000 RPM
D Jetronic: 33° BTDC @ 4000 RPM
10:1 CR pre-H.E. Digital P 24° BTDC @ 3000 RPM

You just can’t get a better authority than Roger Bywater; he was the guy leaning over a screaming V12 in an engine testing room at Jaguar dialing the advance up and down by hand to develop these advance specs.

Yes, the numbers for the pre-H.E.’s sound like a lot more advance than the H.E.; that’s the nature of the beasts – the H.E. gets less advance from the centrifugal mechanism and more from the vacuum capsule than the pre-H.E.

So here’s the new and improved procedure for timing the pre-H.E. V12: Warm up the engine, disconnect and plug the vacuum advance, rev the engine up a little past the specified RPM and then come back down to it and hold it there, and set the timing to the specified advance.

Of course, one problem is that the scale on the timing plate doesn’t go far enough. So, set the crank at 20° BTDC and paint a new mark on the damper at 0°. Then you can use this new mark to set the timing at the spec minus 20°."


Very good, useful info. Thanks much.

An additional question; I completely dismantled the distributor. Would someone know where to purchase the distributor seal? I see Welsh, Moss had them PN 08-1025 old and 28-1025 discontinued but not now. A size would be helpful to cross and or any info on what others have used. As I have read; it is very much unadvisable to run WITHOUT the seal in place.

Thank you

The original seal was an oddity. Most everyone who has the shaft out – which requires unpinning the gear – goes ahead and has the base machined to fit a standard seal. There was a thread on here a few years ago where it was discussed in detail, including the machining dimensions.

Thanks for the reply and info.

Yes the original seal is very odd. I ordered a sealed bearing which is 1/16" wider than stock. I will see if it fits, and if so, consider this little distributor cleaning/rebuild to be a done deal.

BTW the internal weights etc were rusty, frozen, locked together; no possible movement whatsoever. I am thinking I should have a better running engine after I reinstall the rebuilt distributor.

The solution I came up with is to purchase a sealed R8 bearing. The sealed bearing is 0.0625" wider than the factory brg but fit perfectly! I reassembled the complete distributor, installed it, and performed the static timing. The car, seemed to start much better, idled better. I will now attempt to dynamically time the engine. Appears to be a “job” getting a timing light in or around the engine timing indicator.

On a side note; The distributor/timing is adjustable thru the 3 socket head cap screws, mounting the distributor to the engine. The Vernier adjustment on the side of the distributor allows much more adjustment, maybe a finer adjustment, provided the Vernier and adj screw are not broken like on my distributor.