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timing again

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69tr

Jedi Trainee
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I think I have the carburetors pretty much straightened out and now I am working on the timing.

I can set the timing at 12* BFTDC and the car idled pretty good.
When I took it out it ran terrible. I tightened the connections on the coil and checked out the distributor and the car ran pretty good except for a random miss. I checked the timing again and found that the timing mark would move. The mark would go completely out of sight and then come back to 12*.

I called the tech at Moss and he told me what I already suspected. I think I have a distributor problem or a timing chain tensioner bad.

My question is, If the tensioner was bad and the chain was slipping would the timing not remain out instead of coming back to the correct setting?

Thanks in advance, Pete
 
69tr said:
My question is, If the tensioner was bad and the chain was slipping would the timing not remain out instead of coming back to the correct setting?
Click to expand...
If the chain was slipping, the engine would not run at all! And it should take much more than a failed tensioner to make it slip.

Skipping one tooth is a possibility, but it only retards the timing once; and never advances it again.

This may be too obvious, but you didn't mention what makes it move : Note that it's normal for the mark to move when the engine rpm rises.
 
The real problem is probably that the marks on the damper are not reflecting the true ignition timing.
Once the chain stretches and the sprockets wears, along with the teeth on the cam and disrtibutor drive set wear, the timing marks loose their accuracy.
Finding your actual "sweet spot" is still possible if you don't rely on the timing marks to tell you the truth.
A far better way to determine what your particular engine prefers is to use an up to the minute, engine specific, method by observing the intake manifold vacuum. Works every time for every individual engine and you don't have to compare damper marks on a brand spanking completely new engine to one that has some break in and beyond miles on it.
Some back-up here:
https://automotivemileposts.com/garage/v2n8.html
 
poolboy said:
Once the chain stretches and the sprockets wears, along with the teeth on the cam and disrtibutor drive set wear, the timing marks loose their accuracy.
Click to expand...
Just for clarity, none of those things affect how accurate the timing marks are (in terms of indicating the actual position of the crank/pistons).

However, the TR6 has a rubber dampening element in the front pulley, which sometimes loses it's grip and allows the outer ring to shift, which does make the marks inaccurate. It's also possible for the key or keyway to be worn, damaged or missing, which can also affect the timing marks.

To check this with the engine assembled, you'll need to buy or fabricate a piston stop. Should be available at any speed shop, or you can make one by breaking the ceramic out of an old spark plug, threading the shell, inserting a bolt and cutting the head off the bolt.

Mark the damper with the crank turned each way until the piston (gently!) hits the stop. True TDC is halfway between the two marks.
 
TR3driver said:
To check this with the engine assembled, you'll need to buy or fabricate a piston stop.
Click to expand...

I've always seen it done with a spring loaded pin and dial gauge, like this:

699TDC_location.jpg
 
I was refering to the timing marks and the ignition timing, Randall. If there is more space between the teeth of a gear set and a chain sprocket looses diameter from wear on and in between the teeth and the chain takes longer to make a revolution because it has stretched, how could it not affect the relative position marks on the perimeter of the damper with respect to a stationary indicator pointer on the timing cover if someone is using the marks to indicate ignition timing ?
And oh yes how well I know how a defective damper can affect the accuracy of the timing makes thereupon. :cryin:

"It's also possible for the key or keyway to be worn, damaged or missing, which can also affect the timing marks."
You mean something like this, Randall ?
keyslot.jpg
 
Sorry I was not specific before.

I highlighted the 12* mark and zero with chalk. The mark remains stationary except at times when it seems to move. Sometimes it will just move and come back to the correct position. I do have a random miss while driving.

Could a loose connection some place cause the problem? The distributor shaft does not seem to have any slack or play.

From what I am reading it seems that I might as well just order the parts and pull the timing chain cover to find the problem.

Oh well the weather is going to be bad here for the next week anyway.


Thanks, Pete
 
Could just be worn springs in the dizzy and the advance is kicking in and out.
Just a thought.
 
poolboy said:
I was refering to the timing marks and the ignition timing, Randall. If there is more space between the teeth of a gear set and a chain sprocket looses diameter from wear on and in between the teeth and the chain takes longer to make a revolution because it has stretched, how could it not affect the relative position marks on the perimeter of the damper with respect to a stationary indicator pointer on the timing cover if someone is using the marks to indicate ignition timing ?
Click to expand...
That would affect the actual timing of course; but not the accuracy of the marks. IOW, if any of those problems have changed the ignition timing, then you would see the effect of that at the marks (under a timing light, of course).

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]
"It's also possible for the key or keyway to be worn, damaged or missing, which can also affect the timing marks."
You mean something like this, Randall ?
keyslot.jpg
[/QUOTE]
Yup, exactly. Mine hadn't quite sheared the key off yet, but looked very similar. Wore the crank nose undersize as well, I had to use Loctite to keep the pulley on the shaft after that. In my case, I found it because I could actually hear the pulley banging back and forth at idle. The TR3A doesn't have that rubber damping element, and the pulley would actually ring enough that it sounded like someone tapping on a bell. The sound was audible from the driver's seat, only when driving past a wall under otherwise quiet conditions.
 
69tr said:
Could a loose connection some place cause the problem?
Click to expand...
Sure. Anything that would cause the coil to not fire at the right time will make the mark seem to move.
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]From what I am reading it seems that I might as well just order the parts and pull the timing chain cover to find the problem. [/QUOTE]Personally, I wouldn't suspect the timing chain first from your description; at least not without some more tests.

What does the mark do if you slowly rev the engine up and back down? If it is the tensioner, then you should find a dramatic change in behavior at certain rpm (other than the normal motion of the timing as the advance mechanisms come into action).
 
I don't recall the number offhand, but it was a "retaining compound" for cylindrical assemblies. RC609 looks like it might be the stuff
https://www.amazon.com/Loctite-Retaining-Compound-Press-Bottle/dp/B0000YHS8I

They offer a lot more products today, though, so it might not be the best choice. Kind of looks like they don't even offer the RC609 any more; I couldn't find it on the Loctite site, even though it's mentioned many times on their parent company's website:
https://www.henkelna.com/6671.htm?entqr=0...91&start=20

Worked well on my TR3A, but make sure you've got some way to pull the hub off without stressing the rubber sleeve or the pulley flanges. In my case, I was able to run bolts through the holes where the fan extension was originally attached. I'm not sure offhand if that would work for a TR6 or not.
 
Randal, When I rev the engine with vacuum hose attached the timing seems to advance smoothly. I have not held the throttle open for an extended time to see if the mark still moves. When I rev with vacuum hose off then the mark remains on 12*. This is all true except for that occasional movement.

BTW I am running the Pertronix ignition.
 
69tr said:
When I rev with vacuum hose off then the mark remains on 12*.
Click to expand...
That would indicate a serious problem with the centrifugal advance, inside the distributor (under the point plate). I would address that problem before moving on, as it may also explain why the mark moves around sometimes without revving.

I don't have the specs for your engine handy, but with the vacuum line disconnected, you should still see the spark advance, starting at something like 1000 rpm and moving smoothly to something like +25 degrees (from 12 initially) at around 4000 rpm. The advance stops beyond that point (but I doubt you'll want to rev that high without a load anyway).

I'm sure someone will chime in with the 'correct' advance curve for a 69 Federal (I assume) TR6; but those numbers are reasonably close. No movement at all is clearly wrong.

I think you'll be a lot happier with how it runs with the proper advance curve, too!
 
DNK said:
HMMM, I might have validity
Click to expand...
But if you comb your hair right, no one will notice!
 
Randal, I checked the weights and one of them was stuck. I freed it up but I don't see anything else that moves to advance the timing. I am richly ignorant about distributors thus the stupid questions.

It seems that the weights should move something else to advance the timing.

I did put everything back together and had the same problem except that the timing would advance to about 20* when I revved the engine.

Thanks, Pete
 
Thanks poolboy. There is probably more information there than I need to know but it does give me a little more understanding.

OK, I have the distributor out and I am looking at the centrifugal advance mechanism. The fly wieghts are free but the cam is sticking.I can physically move the cam through its range but it does not move easily. What could be causing it to stick? Is the cam supposed to rotate on the shaft?

I think you guys got me on the right track. If you can bare with me a little longer we might get this thing fixed. I won't get to work on it tomorrow. We have friends coming over after church. I think the wife would notice if I went missing.

Pete
 
Maybe just grime or a bit of rust. You might try a little lubricant. Once it gets working Ok a few drops of light oil on the head of the big screw is recommended every now and then. The oil finds it's way down the cam.
 
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