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Distributor diagnostics?

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Tinster

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I'm still trying to get my car streetable.
Multi part question:

Do distributors fail suddenly and leave you stranded?
Or do distributors fail gradually and give you warning?

Is there a diagnostic procedure to test the viability
of a distributor? How can I determine if my distributor
needs to be rebuilt?

Do bad distributors burn up condensor cans?

thanks,

dale
 
Never seen an LBC <span style="font-weight: bold">distributor </span>fail suddenly ... but since I don't trust my electronic ignition, I keep a fully loaded distributor (complete with adjusted points, condensor, cap, rotor and wires) in the center of the spare tire. It's both a source of spare parts, and an easy swap if the electronics module dies (or even becomes suspect) far from home.

Main things to look for are excessive play in the shaft/bearings; and proper operation of the centrifugal advance.

Both can be investigated with a timing light. If the timing mark seems to jump around under the light, the dizzy is worn. As you slowly rev the engine from idle to about 3500 rpm, the timing should smoothly advance. (I forget offhand where it stops advancing for a TR6; likely the value depends on which year dizzy you have.) Then let the rpm drop slowly, and watch the timing go back to it's idle value. If it starts jumping around, or suddenly changes, or doesn't change, there is a problem with the advance mechanism.

As a final check, hook the light up to #6 instead of #1 and check the timing again. Should be exactly the same; if not you may have a bent shaft.
 
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Do distributors fail suddenly and leave you stranded?[/QUOTE] No.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Or do distributors fail gradually and give you warning?
[/QUOTE] No.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Is there a diagnostic procedure to test the viability
of a distributor?[/QUOTE] No.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]How can I determine if my distributor
needs to be rebuilt?[/QUOTE] Please review your credit card receipts. Jeff just rebuilt it. It's fine.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Do bad distributors burn up condensor cans?[/QUOTE]

No, but condensors can suddenly fail without warning because stuff just happens.

It is time to drive the car...............
 
I've never seen a distributor fail suddenly either. Points close yes, condensor fail yes, but nothing else on a distributor fail suddenly. The pin for the drive gear can shear, which would be sudden, but for that to happen there would be a whole lot more going wrong suddenly in the engine internals. Which I HIGHLY doubt is happening. It usually takes many, MANY more miles than you've put on Amos to wear a distributor out.
 
Brosky said:
It is time to drive the car...............
Click to expand...

:iagree:

If your still unsure of Amos' trustworthiness, drive progessively farther with each drive to build your confidence and shake out anymore bugs from what is left, or not left, of Cryptie.

First drive, MINIMUM of FIVE MILES! No more around the block, unless its five miles around the block.

On your next drive double that to ten miles minimum. Double the next one to 20 miles minimum. Keep going until you find the car trusty enough to no longer think about it. Go drive it and enjoy it.
 
"If the timing mark seems to jump around under the light, the dizzy is worn"

<span style="color: #990000">That is EXACTLY what I see.
I tried reversing the clip-on for wire No. 1
and still got the bouncing, jumping timing mark.

The shaft inside the dizzy does NOT wobble.

I'll try the experiment with wire No. 6

I did have the Petronix but it died in under
200 miles. I got just about 1,000 miles from
the condensor.

Maybe Jeff needs to rebuild it again?

thanks,

dale</span>
 
Before you jump to any hasty conclusions try a different wire on the number one spark plug and check the readings again.

Have Wendy hold the throttle steady at 1,000 - 1,500 - 2,000 and 3,000 PMS and observe the readings on each. Then post back.

This would be AFTER you put about 20 well run miles on the car to blow out all of the carbon from the garage cruising.
 
Dale, if you have the points back in you may find that you do get more timing lite fluctuation with the points than with the Pertronics installation. But, if you're not used to looking at this stuff, you may be exaggerating the problem. It's almost certainly not going to stop the car dead in its tracks.
There have been some rotor failures and condenser failures. If you don't feel confident, carry a couple of each with you when you take it for a ride. But, as others have said, make it a good ride so that everything gets up to temperature, the cobwebs get blown out, etc.
Good luck,

Tom
 
Tinster, if the shaft isn't wobbling, I'd check a few other things.

First, of course, make sure you have a good rotor and that your points are set correctly.

One thing that will go "suddenly" is a distributor cap. I had it happen twice (different cars), and the second time I was too stubborn to suspect it. I had my car towed when all it needed was a new cap. There's something about the conductors and the rotor interplay that can make them "go" when they reach a critical point of wear. I doubt your cap is the problem here.

I'd check the wires as others have said, and I'd also check your carburetor shafts. If they suck air, your idle speed will be uneven and that can cause that timing mark to act irradic as well. Proper carb shafts and bushings make a big difference.

If the carbs are set right and aren't sucking air, I'd reset the points, time it, and check it with a light. I can't recall if your car is static timed or not, but you can check it with a light in any event.

I'd not suspect the distributor unless there's something obviously wrong from a visual examination.

What did you do about the gas tank? And domestic pacification?

Good luck.
 
With the rotor firmly in place, move the thing back and forth by hand and observe whether or not it has movement past where the mechanical advance stops the shaft. IOW, as you turn it the "stop" on the plate will halt the shaft, but the rotor may travel further. If so, the rotor has wallowed out and needs replacing. Otherwise, drive the thing.

If Jeff's been thru that diz there's NO NEED to fret over it for YEARS. The points can wear, that's why they're adjustable/replaceable. Condensors the same. They're both small, inexpensive and fit in a glovebox...

Cap and rotor are asked to do a demanding job and can "fail" but usually there's a lot of warning. Post pix of the inside of the cap and the shaft socket of the rotor.

...don't MAKE me come over there. :devilgrin:
 
I'd like to direct you back to the comments of Kentvillehound and Randall about timing scatter/bounce and carbs.

Though intuition tells you that the carbs will have no effect on timing... look carefully again at your carb adjustments. You may find that after as much major work as you have undertaken you need to go through an iterative tuning process where you start with the "basic" carb settings and the default ignition timing, then adjust each a little while paying close attention to the carb balance and mixture. I have seen timing scatter on engines that persisted until both the timing AND the carbs were adjusted. Once the mixture was really right and balanced the timing became very, very, steady. Intuition and logic tells you this shouldn't happen but I've seen it before.

As for condensers burning out... it does happen but I can't think of a reason why it would be in any way associated with a worn dizzy. I haven't been following all the threads here so forgive the following question if it repeats what's been covered in previous threads. You do have the correct coil for your ignition type don't you?
 
tom628 said:
Dale, if you have the points back in you may find that you do get more timing lite fluctuation ...make it a good ride so that everything gets up to temperature, the cobwebs get blown out, etc.
Good luck,

Tom
Click to expand...

<span style="color: #CC0000">So OK!

I took the Crypt Car out and performed the EYE-tal-yun
tune up, as suggested. 1 hr and 50 minutes drive time should
have blown out some carbon.

Now, I'll next perform the timing light diagnostics and post
back with findings.

thanks one and all for your generous help and suggestions.

This car is getting closer and closer to being streetable.

yup! :yesnod:

Dale</span>
 
Ya drove it on the Street today dinja. Then it's street able.
 
Continuing with sorting out the carbs and ignition:

I pulled the No5 cyclinder plug this morning and
this photo is what I found. I know there are plug
images for comparison but what can the Triumph experts
tell me from looking?

Also a small question: Where is engine vacuum tested?
I attached my vacuum meter to the intake manifold nipple
that goes to my brake canister. Is this correct? I got 20.

thanks, dale

plugsNew2.jpg
 
That plug looks fine to me. Just perfect, considering that your driving is mostly low speed, short trips.

Vacuum gauge can be connected anywhere there is manifold vacuum; the nipple for the brake booster is fine. 20" and steady is also fine. There's a nice chart of vacuum readings and likely causes at
https://www.classictruckshop.com/clubs/earlyburbs/projects/vac/uum.htm
 
Wow, Randall-Thanks!!!!

I had no idea such a graphic chart existed.
What a great diagnostic tool.

Now off to the Doc's.

d :thumbsup:
 
ALL of our plugs should look so good!
 
Please remember that a camel was once a great race horse until engineers got their hands on it. Read as over analyzing.........

Stop looking for problems and drive the car. It's the best medicine for you and the car.
 
This is a general question related to Tinster's.

None of my LBCs have had the vacuum advance/retard distributors, they have all been advance only. Those connected to a venturi port on the carb for ported vacuum, not the intake for manifold vacuum. So... when did BL introduce the advance/retard distributors?
 
The vacuum retard was introduced around 1968, in response to new emission control requirements. The dual advance/retard was only used for a few years, then they went to retard-only.

Some cars didn't have vacuum retard but instead extra mechanical advance, so the idle timing could still be 4 ATDC but it would advance to the normal range once the engine was revved to operating rpm.

In theory, the retard at idle helps lower HC (unburned hydrocarbons); while the lack of vacuum advance helps lower NOx (nitrogen oxides). But better methods were found to control both of these pollutants later on, so it was only the 70s engines that were saddled with such poor compromises.
 
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