PDA

View Full Version : TR2/3/3A Setting the timing on TR3



LexTR3
05-03-2011, 04:50 PM
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 (?)

Geo Hahn
05-03-2011, 05:56 PM
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.

TR3driver
05-03-2011, 06:20 PM
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.

LexTR3
05-03-2011, 06:24 PM
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?

TR3driver
05-03-2011, 06:59 PM
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).

LexTR3
05-03-2011, 07:17 PM
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.

TR3driver
05-03-2011, 07:30 PM
Why wouldn't the static procedure and the dynamic procedure (using an advance timing light) work equally well?

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)

LexTR3
05-03-2011, 07:48 PM
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).

bnw
05-03-2011, 08:06 PM
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.

LexTR3
05-03-2011, 08:50 PM
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.

poolboy
05-03-2011, 09:18 PM
And yet another method of finding the ignition's sweet spot.
https://automotivemileposts.com/garage/v2n8.html

LexTR3
05-04-2011, 07:41 AM
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.

karls59tr
05-04-2011, 07:42 AM
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

vivdownunder
05-04-2011, 09:29 AM
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.

Geo Hahn
05-04-2011, 12:17 PM
...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?

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.

LexTR3
05-04-2011, 12:56 PM
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.

TR3driver
05-04-2011, 02:40 PM
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.

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.

LexTR3
05-04-2011, 03:23 PM
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?

Geo Hahn
05-04-2011, 03:47 PM
...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 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.

bnw
05-04-2011, 03:49 PM
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.

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.

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.

LexTR3
05-04-2011, 04:02 PM
Hi, George,

I had the points replaced and set a few weeks ago by the mechanics in the shop where I have most of my work done. They did not check the timing.

When I decided to check the timing, another mechanic friend of mine showed me how to use the advance timing light. What we found was that the timing was "off" just a little bit, and when we rotated the distributor a very little bit and took the rpms back up to 1000 (from 500 where we set it for adjusting the timing) it idled better than it ever had.

As for running, acceleration, etc., the car runs extremely well -- very smooth, very peppy, no pinging.

With high rpms, the timing light remains "right on the mark." I don't see any wandering at all.

TR3driver
05-04-2011, 04:05 PM
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.
Ok, how are you going to watch the timing mark, while accelerating to pass?

And, what timing specification are you going to use?

I agree a light is useful; but AFAIK we were talking about setting initial timing, not total.

JohnnyMead
05-04-2011, 04:07 PM
A timing light let's you see the total advanced timing (within the confines of running the engine up with no load).
I use a timing light to get the initial setting because I've got pertronix and have not gotten the hang of static timing with the electronic gizmo.
John

Twosheds
05-04-2011, 04:15 PM
I had the points replaced and set a few weeks ago by the mechanics in the shop where I have most of my work done. They did not check the timing.

Changing the points usually changes the timing.

karls59tr
05-04-2011, 04:17 PM
JohnnyMead What is the process for setting the initial timing with a timing light if you have pertronix?

LexTR3
05-04-2011, 04:27 PM
Dr. John,

Then the mechanics who changed the points and set them, should have checked the timing. I'll ask them to do that next year when I go in for my "spring tuneup."

On this subject, will installing a new vacuum advance unit (Moss has reduced the price of their new ones) change the timing if I am careful to mark the position of the distributor and make sure it is returned to that position after I install the new unit?

TR3driver
05-04-2011, 05:21 PM
On this subject, will installing a new vacuum advance unit (Moss has reduced the price of their new ones) change the timing if I am careful to mark the position of the distributor and make sure it is returned to that position after I install the new unit?
Very likely, yes. If you are doing the "mark the position" thing, then you'll also need to mark or note the posiiton of the timing vernier, since it has to be undone completely in order to change the vacuum module.

TR3driver
05-05-2011, 12:29 AM
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?
Depends on where the advance starts. ISTR the book gives 0 to 2 degrees at 350 rpm for the early distributor, checked with the rpm falling.

The hand crank may not be the reason it has such a screwy advance curve. Maybe it's just a 50s British thing like Lucas fuse ratings, I dunno. But it does have it, while those other cars didn't (at least not mine).

And that still doesn't solve the problem of where you buy 95 octane gasoline today.

HerronScott
05-05-2011, 06:25 AM
[And that still doesn't solve the problem of where you buy 95 octane gasoline today.

Randall,

Wasn't that 95 octane rating specified then the RON measurement versus today's AKI or PON rating? From what I've read that 95 RON would be 90-91 AKI today.

Scott

bnw
05-05-2011, 06:41 AM
Correct. Two different ways to compute.

LexTR3
05-05-2011, 07:29 AM
Randall,

If I install a completely new advance vacuum module, and I have to remove the timing vernier to get the old one off, it seems to me that either (a) I would have to reset the timing with the dynamic/timing light method, or (b) I would have to reset the timing using the static/vernier knob method. I don't think I can mark the old vernier knob and get the new one to conform exactly.

At present, it appears that my old vernier knob has absolutely no effect, so it doesn't seem to matter what its position is. I ignored it when setting the timing with a timing light (and rotating the distributor).

One thing to remember about all these "proper settings," I am told, is that the Triumph people estimated as optimum when they designed the system. But their guess was limited by all the variables of temperature, altitude, humidity, quality of the gas, and half a dozen other things. In otherwords, it was a wild guess. Their testing was in cold, drizzly England. I am learning that these old cars never do better than an approximation.

JohnnyMead
05-05-2011, 10:38 AM
JohnnyMead What is the process for setting the initial timing with a timing light if you have pertronix?

As I recall it was attached in place of the points without touching the dizzy's position, then started and adjusted. Maybe that was the "dumb luck" approach.
John

LexTR3
05-08-2011, 09:33 AM
Well.... after all this time and effort... and many tries to set the timing properly on my Triumph (using static and dynamic methods), it has all been a futile waste of time....


.... because I discovered that the spring in the distributor is either broken or shot.

With the distributor not working properly, it is nearly impossible to balance the carbs, set the mixture, etc., etc., and certainly to set the timing.

Also determined that the idle has been set too high (1100 rpms) with needles that make the mixture too rich with the consequence that too much fuel has been pumped into the system... contributing to the dieseling problem I have had.

So.... First to replace the spring in the distributor....

Then to check and replace the needles in the carbs....

Then to set the timing properly (most advice is to use a timing light) and then to adjust the carbs, mixture, and idle...

The spring probably costs about 8 cents, but has cost hours of fiddling with the other components! An expensive lesson.

I hope this helps others...

TR3driver
05-08-2011, 10:08 AM
Just curious, Ed, are you talking about the spring that links the vacuum module to the point plate, or one of the centrifugal advance springs?

Also, regardless of what needle is installed, the idle mixture is still controlled by the mixture adjustments. A "rich" needle only admits more fuel off-idle.

TR3driver
05-08-2011, 10:12 AM
Wasn't that 95 octane rating specified then the RON measurement versus today's AKI or PON rating? From what I've read that 95 RON would be 90-91 AKI today.
Yes, that is true. However, the relationship between AKI (which is the average of RON and MON) and RON is not fixed, and is only recommended to be 5 or less.
https://www.faqs.org/faqs/autos/gasoline-faq/part3/

Plus, at least around here, 89 is the highest available and many places only carry 88.

Unless you buy racing fuel or avgas, of course.

HerronScott
05-08-2011, 10:35 AM
Randall,

Interesting. Here in VA, you still have Regular (87), Midgrade (89) and Premium (91) available almost everywhere. Any idea why CA would have more limited choices? And what do owner's of cars that specify or require higher octane do (My wife's 2005 Thunderbird and my brother's Infiniti G35 both specify 91 octane minimum for example)?

Scott

TR3driver
05-08-2011, 10:55 AM
Sorry, my bad. We do have 91, just not 93 and up.

But practically any car made in the past 20 years will have a knock sensor, allowing it to run on lower octane fuel without damage. They just burn less if you use premium.

poolboy
05-08-2011, 03:00 PM
Stop fiddling. Send the distributor to Jeff Schlemmer at Advanced Distributors and get it back the way it's supposed to be, advanced weights, springs, advance module and free of slop.

LexTR3
05-09-2011, 07:57 AM
Its one of the centrifugal advance springs. Actually, a mechanic friend of mine found the problem, and he is going to install the new proper spring (from the five available).

Further inspection may show that one or both of the bushings are worn and need replacing. there is a lot of play in the unit.

Poolboy -- you are right. This winter, when the driving season is over, I plan to have the distributor entirely rebuilt, along with some other work on the car. I depend on a shop north of me that specializes in British sports cars, and they will send the distributor off for me and reinstall it, tune the car, etc., etc.



In the meanwhile, it's driving time around here.

Many thanks.

DNK
05-09-2011, 10:26 AM
Ed, suggestion. Buy a used one, if so available, and send that out now and then install when it arrives.
No loss of driving and you get to enjoy earlier

LexTR3
05-09-2011, 11:36 AM
Don,

Good idea, but two problems:

(1) I wouldn't have the slightest idea how to remove the old distributor. A mechanic friend of mine said there are several types, and each is removed in a different way. Knowing my usual luck, I'd get it half way out and wouldn't be able to remove it..... Or, just as bad, I probably wouldn't be able to get it back in. Mechanic friend (not the shop guys who would do the work for me) said that depending on the model, I might have to adjust it in come complicated way. I think I would get into real trouble if I tried it myself. (I'm definitely a "beginner" at mechanical work).

(2) I wouldn't know where to buy a used one, and I would be a poor judge of the quality of the used one. Might just be substituting one bad one for another.

With a new spring, my mechanic friend said that my current distributor should be good for another 5000-6000 miles before absolutely having to be rebuilt. He is going to install the spring (or show me how) and will check the condition of the bushings while he is at it.

So, despite your excellent idea, I think I'll keep the old one going until winter arives, and then I'll take the car to the shop and let them fuss with it.

70herald
05-09-2011, 02:57 PM
Don,


With a new spring, my mechanic friend said that my current distributor should be good for another 5000-6000 miles before absolutely having to be rebuilt. He is going to install the spring (or show me how) and will check the condition of the bushings while he is at it.


When you do have the dizzy rebuilt, just have your friend take it off and then SEND IT TO JEFF AT ADVANCED DISTRIBUTORS... He has the experience and equipment to set it up correctly.... Particularly since fuel has changed in the last 50+ years, the engine has probably been modified etc etc.... he will set the dizzy up to match the current conditions, not what may have been correct in 1950.

LexTR3
05-09-2011, 05:09 PM
Hi Don,

Thanks for the advice. The shop I deal with has done a lot of work for me, and a lot of good work. I have already talked to them about rebuilding the differential this winter and other projects. I feel obligated to take the distributor to them as well, and I feel certain that they have someone they contract with to do these rebuilds. The shop specializes in British sports cars, but has worked on many others as well for about 25 years, and has an excellent reputation. So I don't think I'll be sending the dizzy to Jeff, although I know that he comes highly recommended. Thanks, anyway, for the recommendation.

Fuel has changed, indeed, but we are lucky down here, at least for the time being, to have non-ethanol gas readily available.

HerronScott
05-10-2011, 01:13 AM
Sorry, my bad. We do have 91, just not 93 and up.

But practically any car made in the past 20 years will have a knock sensor, allowing it to run on lower octane fuel without damage. They just burn less if you use premium.



Randall,

My mistake here as well as the Premiums here are 93 and not 91 which you would think would be inline with the 95 RON of the 60's.

And you are correct on any modern car being able to retard the timing in response to detonation. I was thinking more about older muscle cars which wouldn't have that benefit.

Scott

TR3driver
05-10-2011, 12:08 PM
I was thinking more about older muscle cars which wouldn't have that benefit.

Which brings us back full circle; to having to set the timing based on what the engine responds to best with the available fuel.

Another alternative, which I've wanted to try for many years but haven't, is water injection. Supposedly water is very beneficial to the combustion process, especially when trying to run a high compression (or supercharged) motor on lower octane fuel. Maybe someday ...

LexTR3
05-10-2011, 07:48 PM
And talking about bringing us back full circle. I mentioned earlier that the trouble I was having setting the timing on my car might have been due to a poor advance return spring in my distributor. (I subsequently found out that there are two springs in the distributor, not one.)

Today I received a small package from Moss containing five advbance return springs, none of which matched. I called Moss technician for instructions and learned:

(a) these springs almost never, ever break

(b) there are two springs in the distributor, one weaker than the other

(c) five springs give me some choice of performance, but no one could explain how the performance would vary

(d) problem is probably goop build-up in the distributor inhibiting the return.


Has anyone had experience with these springs? Of the five, which two are best to use (Or probably just try to match the ones presently in the car).

This is all stop-gap, because I intend to have the distributor rebuilt this winter.

TR3driver
05-10-2011, 08:12 PM
If the problem is not the advance springs, then why not just keep the old ones?

Clean and lubricate the advance mechanism, then don't forget the drop or two of oil every 6000 miles (or year, whichever comes first).

The springs are not really "return" springs at all, but rather they determine the amount of centrifugal advance by resisting the force exerted by the weights. The heavier spring is supposed to be loose "as installed", since it only comes into play at higher rpm (giving slower advance above a certain rpm).

So it's not important that the springs pull the point cam all the way back against the stop (it will be pulled there by friction from the point rubbing block even without the springs).

Moss should be able to tell you which springs are suitable for which distributor.

Here's a little chart I made some time ago, showing some of the different factory advance curves

poolboy
05-10-2011, 08:29 PM
You would be risking the destruction of your pistons by trying to select the springs yourself. Selecting the wrong spring could result in over advancing the ignition timing. "Preignition" or "Detonation" .Look that up on the net.
You should not drive the car without proper advance.
Bring the dizzy to your mechanic or cut out the middle man and send it directly to Advanced Disrtibutors.
Unless you think you or your mechanic can figure all this out.
https://www.jcna.com/library/tech/tech0015.html

LexTR3
05-11-2011, 09:16 AM
Randall and Poolboy,

Thanks very much for the caution and information.

I am no mechanic, so I wouldn't try to do any of this myself. I am being helped by a friend here in town who had a shop for about 30 years where he worked on foreign cars. He has repaired and rebuilt these distributors many times, so I feel confident he will know what to do.

He checked out the timing and the distributor and determined that something was wrong -- possibly a problem with the springs. But he did nothing more at that time.

Tomorrow he will come by and remove the plate in the distributor and check the springs and other elements to see if he can see a problem. Then he will decide either to fix it, or if it is beyond easy repair, he will recommend sending the distributor off to be rebuilt.

I'll let you know what we find.