TR2/3/3A Setting the timing on TR3

I am picking this up from an earlier thread I started on setting the air/fuel mixture.

My question is: what is the best way to set the timing on a TR3?

I have read the very helpful and detailed instructions from Mark Macy that recommend using the micrometer adjustment nut on the vacuum unit, and that using a timing light won't work.

But a mechanic friend of mine who has been working on these cars for years convinced me that using a timing light will do just fine, if done properly.

So, with points set properly, I marked with white paint the timing mark on the crankshaft pully, reduced the throttle screws for about 500-600 rpms, loosened the distributor clamp, attached the timing light (set to proper advance of 4 degrees), and checked where the TDC mark on the pulley was in relation to the indicator. It was off some. I turned the distributor slightly until the mark was under the indicator and then rechecked the timing. Then I tightened the distributor cap and rechecked the timing. Then I brought the rpms back up to about 1000 and once again checked the timing. The car idled better than ever.

What seems to be the objection to using a timing light?

BTW -- When I tried to use the micrometer adjustment nut method, it had absolutely no effect. Probably has to be replaced (?)

Whatever works for you but I prefer to initially set the timing static using a light bulb or buzzer to determine the moment the points open.

Isn't the 4* spec for a static timing? -- seems like a running engine (even at very low RPM) would see some advance, making the timing light less certain.

In any case, I make my final adjustment based on what I hear on the driving test. That vernier adjuster should work... is the end inside the dizzy properly hooked over the little knob? Does the movable plate move freely? That adjustment is great for fine tuning and even adjustment for a tank of poor gas obtained on the road.

My objection to using a timing light is mostly that the factory timing is no longer appropriate for modern fuels. Where are you going to buy 95 octane gasoline (rather than the gasohol that is mandated in most of the USA)?

The road test is far preferable, IMO. And just like the mixture varies somewhat with altitude, air temp, and fuel; so does the optimum advance. I backed mine off a couple degrees last night, because the engine was pinging when it got really hot.

George,

I don't know enough about the makeup of the vernier adjuster to know if it is hooked up properly. Can you direct me to photos or drawings?

As for the 4 degrees, my understanding has been that dynamic timing is possible with a timing light that can be adjusted to compensate. Wouldn't you achieve the same thing with such a timing light as turning back the vernier adjuster after setting the static timing?

When you turn the thumbwheel/nut, you should see the vacuum advance module move towards or away from the distributor body. In fact, the marks on the vacuum module where it enters the body is how you check to see how far you've moved it. In spite of the "vernier" appellation, there is some friction/backlass in the mechanism, so you may not immediately notice a change in engine timing. But after driving, it will settle to the new value.

Inside the distributor, there is a long spring that comes out of the vacuum module and hooks over a post on the point plate. This is the same link that changes the timing when the vacuum advance operates. If you take the cap off and look inside, you should be able to see that the point plate moves along with the advance module (after you move it far enough to overcome the friction & backlash).

Randall,

Thank you very much for the explanation and the description. It paints a very clear picture for me and will help if I try the static approach.

But I still have a question...

Why wouldn't the static procedure and the dynamic procedure (using an advance timing light) work equally well? Seems to me that they are two approaches that lead to the same outcome: a properly timed engine. The TR3 has a distributer that can be loosened, a timing mark on the pulley, and an indicator ... Other cars I have had (1970 Pinto, for example) had the same elements and the dynamic procedure was what I always used to set the timing. Is it just a matter of preference, or is there a substantial issue here? The dynamic procedure seems simple and efficient.

LexTR3 said:

Why wouldn't the static procedure and the dynamic procedure (using an advance timing light) work equally well?

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1) With the engine running, the centrifugal advance has moved the timing by an uncertain amount. You aren't necessarily setting initial advance.

2) Neither one produces "correct" timing, only an initial estimate. Just like the mixture, you use an initial timing to get the engine running, and then test to see what it "wants". But since you can't set the dynamic timing until the engine is running, it is a worthless procedure. (In this case)

That's an eye-opener for me since setting timing with a timing light has always been "the normal procedure" for me. I see what you mean in "2" above, and am now inclined to try the static timing procedure.

But one last question: Is the difference between the two procedures so critical as to make the dynamic procedure "worthless"? I ask this because after setting my timing with the dynamic procedure, it has run extremely well (and it has idled better than ever).

There is absolutely nothing wrong with using a timing light. Engine running both at idle and at speed is "live", or dynamic. The timing light "sees" the wear in the distributor, the tension of the advance springs, the pull of the vacuum diaphragm. Centrifugal advance at idle is non existent. In essence, it shows what's really going on. Static timing is just that. Static / dead. It's a great way to set things up but that's all. You won't know what is really going on without a timing light. You may still have to adjust for octane issues, altitude, etc.

bnw,

I'm no mechanic, but what you say about the timing light's ability to reflect what is actually "going on" with the engine seems intuitive to me.

The lesson that I am drawing from this interesting discussion is that there are at least three ways to check and set timing, and that using a timing light is as valid as the other methods.. and that neither is "perfect" or "final."

You have alluded to it, and Randall has mentioned it: setting the timing is not the entire solution to getting your engine to run smoothly and efficiently. There is still the matter of balancing the carbs and setting the mixture properly, etc., etc.

After all is said and done, I have to say again that after I adjusted the timing with the dynamic procedure (advance timing light), the car ran better than it did before. In fact, the car runs like a "new car." Perhaps I'll stick with that for the time being.

But I am interested in all the different methods -- pros and cons -- and, as usual, have learned much from this discussion.

And yet another method of finding the ignition's sweet spot.
https://automotivemileposts.com/garage/v2n8.html

poolboy,

Thanks for this alternative method. I will add it to my collection of timing procedures, that now is up to four.

Even when my timing was a bit off, I never heard any pinging in my engine. It is a very smooth running engine. Starts well, even in cold weather, runs well in cold or high heat, and gives decent gas mileage. My only recent problem was that it was running a bit rich and dieseling when I cut off the engine. I believe I fixed this by leaning the carbs.

Hi all I've adjusted the valves and installed new plugs on my TR3. I've mounted two rebuilt SU's that I haven't dialed in yet. Do I adjust the carbs as best I can First and then set the timing or set the the timing and then the carbs? Can you do a static timing with a Pertronix? What mark on the damper is used for timing with a light? What rpm do you run it up to for the dynamic timing? Thx Karl

If anyone has tried to use a timing light on four potter TR, it's immediately apparent you can't get the strobe over the timing tang. The water pump pulley is in the way.

You can angle the strobe light down above the generator between the fanbelt and the block, but that's not really accurate. There's an element of good luck if the timing comes out right.

The engine was designed for static timing, then making a final road adjustment via the vernier on the dizzy. Basically that's to accelerate in top gear from a low speed and if it pinks, back off (retard) the vernier until it stops.

With every engine different after various rebuilds and fuel varying between countries, "static and vernier" remains a one size fits all approach to timing a TR.

Viv.

karls59tr said:

...mounted two rebuilt SU's that I haven't dialed in yet. Do I adjust the carbs as best I can First and then set the timing or set the the timing and then the carbs?

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I would set the timing first using a static setting, then sync and adjust the mixture on the carbs.

No idea how you set the pertronix, have heard of some who set the ting up using points then change to the Pertronix afterward all is well.

George,

You've said that you prefer using the static setting. Can you tell me why (just curious about it, not questioning your preference), and have you ever used the dynamic setting?

I'm still a bit puzzled over folk's reluctance to use the dynamic setting, as the TR set up seems just like the old 4-cylinder Fords and Chevys of the 1960s and 70s, and they were routinely adjusted with timing lights. Also, by putting white paint above the timing mark (the hole on the crankshaft pulley), I have a very good view of it and the indicator with very little angle -- no problem.

LexTR3 said:

I'm still a bit puzzled over folk's reluctance to use the dynamic setting, as the TR set up seems just like the old 4-cylinder Fords and Chevys of the 1960s and 70s, and they were routinely adjusted with timing lights.

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The difference is that those Fords and Chevys were not equipped with hand cranks. Because the TR2/3 was, it has a static timing that is slower than is usual in engines that don't get hand cranked; and a centrifugal (rpm based) advance curve that starts BELOW normal idle rpm.

Randall,

Very interesting. But wouldn't the procedure of lowering rpms to 500-600 and using a 4 degree advance timing light when adjusting the timing make up for the difference?

TR3driver said:

...Because the TR2/3 was, it has a static timing that is slower than is usual in engines that don't get hand cranked...

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And that, I suppose, makes it easy to start and lessens the chance that I will break something (like a hand or thumb) when I crank start the engine?

Ed - no reason why you can't use a timing light once you figure out where the mark should be at the idle you select -- I suppose the static method is just so darn easy I never tried anything else. You already have the dizzy cap off and are turning the engine by hand (since you must adjust the points gap before setting timing) so it is simply a matter of connecting 2 leads (battery and points) to find the timing.

I do use a timing light to see the advance at high rpms to satisfy myself that it is working freely. The light also gives some idea of how much the timing wanders (wobbly dizzy shaft?) at a steady speed.

TR3driver said:

LexTR3 said:

I'm still a bit puzzled over folk's reluctance to use the dynamic setting, as the TR set up seems just like the old 4-cylinder Fords and Chevys of the 1960s and 70s, and they were routinely adjusted with timing lights.

Click to expand...

The difference is that those Fords and Chevys were not equipped with hand cranks. Because the TR2/3 was, it has a static timing that is slower than is usual in engines that don't get hand cranked; and a centrifugal (rpm based) advance curve that starts BELOW normal idle rpm.

Click to expand...

With all due respect, I don't buy it. IMO, it's not the idle timing anyone should be concerned with. It's the driving down the road, accelerating to pass timing at road speed that really matters. You're only going to see if everything is working properly with a timing light.