Just curious

[Member 10617]

If you are like me, when someone suggests something for your car and it not only works but makes a dramatic improvement in its performance, you are curious to know why or how the suggestion worked.

That is the case with my rebuilt Lucas 40480 distributor.

The rebuild came with instructions to set the timing at 15 degrees BTDC at idle, without vacuum. I know the main reason for this has to do with a change in the advance curve that was made to the distributor in order to better deal with today's fuels.

In addition, it was recommended that the vacuum advance be set almost to the extreme advance position on the vernier scale before setting the timing (that position, in other words, would be the starting position for the timing procedure). The explanation that came with this recommendation was that with any other position on the scale, the distributor would run into phasing problems (the rotor would not be in the right position when it tries to fire to the cap terminal).

I followed these instructions, and the car runs very well, indeed.

But I don't know how or why the phasing would be affected by screwing the vacuum advance to the advance position on the vernier scale. I'm not questioning this recommendation (because it works extremely well), but I am curious and would really like to understand what's going on and why.

I'm not sure why any point on the vernier scale couldn't be used as the "initial" setting (except that in my case it has something to do with phasing). Most manuals recommend that you set the vacuum advance on the midpoint of the scale and then set the timing. That would allow for adustments up and down the scale on road tests.

Again, I am not questioning this recommendation because it works so very well for my car -- and I'm not proposing to change the adjustment -- but I'm really interested in learning why it is correct and why it works so well.

Can one of you tech-savy guys shed some light on this for me? I would really appreciate the information, and perhaps it will help others as well.

 

[TR3driver]

I don't know that it is correct, but I'll try to explain why it might be correct.

'Phasing' refers to the relationship between the rotor tip and the post in the distributor cap, when the spark happens. The spark happens when the points open, so anything that affects the relationship between the points and the distributor cap will have some effect on phasing. When you change the vernier adjustment, it moves the point plate (and hence the points) but does not move the cap. Thus it changes the phasing slightly.

I've never heard that the factory phasing was particularly poor, so I wonder if one of Jeff's modifications has changed it in some way. He is obviously replacing the point cam, so maybe his replacement cam doesn't have quite the same relationship built into it or something.

Might be entertaining to cut a hole in an old distributor cap (ala Geo's "visible distributor") and observe the phasing. I almost did that myself, back when I was having so much trouble with a Crane XR3000 but I managed to find my problem without actually cutting a cap.

 

[poolboy]

I had a problem with phasing in my TR6 distributor with a Pertronix Ignitor installed.
It wasn't evident until the centrifugal advance was close to'maxing'out. Seems like it was around 4500 rpms before the spark started breaking up. I spoke with Jeff about it and without going into a bunch of detail, with the vernier fully retarded I rotated the distributor counterclockwise (retarded) a few degrees then returned to my my sweet spot by advancing the timing with the vernier knob
Sounds like the opposite of what you were told, Ed.

 

[TR3driver]

with the vernier fully retarded I rotated the distributor counterclockwise (retarded) a few degrees then returned to my my sweet spot by advancing the timing with the vernier knob
Sounds like the opposite of what you were told, Ed.

Actually, that sounds just the same to me. Having the vernier advanced farther than before solved the problem.

 

[Member 10617]

Randall and Poolboy,

You've made it much clear for me. Once again, many thanks.

I think I am beginning to undertstand now. But understand or not, I can say -- happily -- that the car has regained its old pep and now zips along the highways and byways (and hills and mountains) like a new car. Smooth idle, no hesitations on acceleration, no run-on when shut off....

My friends say I am over-thinking my tractor engine.... Ha, ha. Guilty as charged!

 

[poolboy]

with the vernier fully retarded I rotated the distributor counterclockwise (retarded) a few degrees then returned to my my sweet spot by advancing the timing with the vernier knob
Sounds like the opposite of what you were told, Ed.

Actually, that sounds just the same to me. Having the vernier advanced farther than before solved the problem.

In the first case (Ed's) the timing can only be retarded with the the vernier pre set at full advance. That is after the timing has already been retarded by rotating the distributor ccw in order to more closely align the rotor with the contact in the cap...during the moment the spark occurs
With the procedure that I was told to try, you retard by ccw dizzy rotation to align the rotor with the contact during ignition, but you stil have the vernier with it's full advance capability to move the point plate to the timing's sweet spot without affecting the alignment of the rotor.

 

[TR3driver]

Uh, Yeah, Ed was told to move it all the way, while you were told to only move it partway. So he wound up with the vernier fully advanced, while you wound up with it mostly advanced. A distinction, yes, but not "the opposite".

Come to think of it, how is it that your TR6 has a vernier? I thought was deleted when the vacuum retard was introduced. Are you running a PI dizzy?

 

[poolboy]

I had Jeff Schlemmer install this while he had the dizzy in his shop.

I wouldn't say I ended up 'mostly advanced' I just used the vernier to bring the timing back to where it was before I retarded it in order to bring things back in phase. As you can see after all is said and done I'm about midway within the adjustment range of the vernier.

The difference as I see it is Ed starts out with the vernier fully advanced and I start out with it fully retarded.
That's what I mean by opposite. I don't know what other word describes it better.
Whether Ed actually manipulates his vernier to zero in, I don't know but I did..and do..
BTW, from what I gather, the out of phase condition is something that TR6 folks with a Pertronix installed might encounter..hardly a problem to be concerned about otherwise.

 

[Member 10617]

To be exact, Jeff didn't set my vernier to full advanced. He set it 3 1/2 divisions advanced, leaving at least 1/2 of a division until reaching full advance. And since 1/4 turn can make a difference, I still have a few adjustments left until I reach what appears to be full advance. I know this is not much, but I just wanted to set the record straight.

Once I set the timing by rotating the distributor and tightening it in place, I do not change the setting on the vernier scale that Jeff recommended. I leave it at 3 1/2 divisions toward Advance, and I leave the thumbscrew alone.

The proof of the pudding is in the eating, as they say, and I can say that the car runs exceptionially well now.

 

[poolboy]

Quote,
"In addition, it was recommended that the vacuum advance be set almost to the extreme advance position on the vernier scale before setting the timing (that position, in other words, would be the starting position for the timing procedure). The explanation that came with this recommendation was that with any other position on the scale, the distributor would run into phasing problems (the rotor would not be in the right position when it tries to fire to the cap terminal).

I followed these instructions, and the car runs very well, indeed"
End Quote
'

So that's what "almost" meant. Thanks for clearing it up. :crazy:
I guess what I did was almost the opposite of what you did.

 

[Member 10617]

Yep... "almost," in this case -- looking at a close-up photo of the distributor as it appeared when I received it and a backup distributor that I subsequently purchased -- means 3 1/2 divisions toward advance, or so it appears to these old eyes.

And just to make things clear, it was recommended that I not move it from that preset position.

Though this puts me almost to the full advance position, I can still perform Don Elliott's road test procedure if I need to.

It works for me...

 

[Member 10617]

Poolboy,

Just to make things more interesting....

When I had my car tuned up a few months ago by a shop that works on Triumphs, when setting the timing they set the vernier scale almost to the full Retard position. I didn't take notice... but the car ran fine.

When I had to reset the timing the other day because of having taken the distributor apart to find a missing screw, I first reread the instructions that I had received from Jeff. There I found that he recommended that the vernier scale be set most of the way to the Advance position.

Which one to choose?

I went with Jeff's recommendtion for two reasons: (a) he was the person who rebuilt my distributor, and (b) he warned of the phasing problem.

Seems like there are two ways to do this... depending on how the distributor has been modified or adjusted or whatever one does when one rebuilds it.

 

[poolboy]

He actually warned you about phasing ? I didn't think it was much of a problem with you TR3 guys.

 

[Member 10617]

Hi, Poolboy,

Here's what he said: "The vacuum advance should be left very close to where I set it or you'll run into phasing problems (the rotor won't be in the right position when it tries to fire to the cap errminal.) I screw them most of the way out toward the Advanced Direction."

As I said earlier, the guys at the shop who work on my car recently adjusted timing with the vacuum advance set almost at the FULL RETARD POSITION (their method). When I looked at a photo of the distributor as it looked when I received it from Jeff, I saw that he had set the the vacuum advance at 3 1/2 divisions toward the ADVANCED DIRECTION (in line with his instructions to me). Thus, the other day when I reset the timing after having pulled the distributor to find the lost screw, I set it based on his recommendation -- advance set at 3 1/2 divisions toward the Advanced Direction on the vernier scale -- and it worked very well for me.

My knowledge of "phasing" is pretty limited; thus my posting asking for an explanation. Just curious to know...

 

[poolboy]

As long as you're happy and the engine is happy, Ed, that's what counts
Me, if there is an adjustment of any kind, I'm likely to try my hand at it, figuring it must be adjustable for a reason.

 

[Member 10617]

Hi, Poolboy,

Thanks.... yes, the engine seems to be happy, and that makes me a happy driver. I'd much rather be in the car than under it, any day. (10,000 miles logged on since the end of 2009!).

Given the choice, I prefer to try the adjustment myself. I do try my hand at a lot of adjustments, but if I don't have any idea what I'm doing and can't find useful information, I have to turn to others who do know what they are doing. I've been lucky in fixing some things, like my carbs, timing, horns, and a multitude of other little things, but I have also screwed up some things when I didn't have adequate information, like adjusting my regulator.

I began this adventure with absolutely no confidence in my ability to work on this car. But gradually I have learned that as good as the experts are, they don't always get it right. I think the trick is to try to do things yourself, but to know one's limitations.

One thing for sure, without BCF, I'd have a much harder time.

 

[poolboy]

It had been a long time since I HAD to work on cars when I got my 74 TR6, but having done so in the past, I did not lack the confidence in my ability to do so.I would not have gotten involved with another old sports car without that confidence.
The actual desire work on cars again though.., well, that was another story. I just wanted to fiddle with the small stuff and enjoy driving around out here in the country when everybody else was off at work.
As with most things in life, at least my life, things didn't turn out the way I expected or hoped. 2 engine overhauls and 2 engine rebuilds in 2 TR6's got in the way of some of that driving time., but aside from paying for machine work, I haven't had to spend any of my limited retirement money on anything but parts thanks in part to the members of 6-Pack.
I'd like to tell you that I think I have a reliable car right now that I could drive anywhere anytime, but with my luck that would only jinx it..so....

 

[Member 10617]

Hi, Poolboy,

In 1962, I had a 1958 TR3, but all I ever tried to do to it was to balance the carbs (not very successfully). It was practically a new car, so it really didn't need much work. In the early 1970s, I had a Ford Pinto (one of the last easy cars to work on) and I learned to change the points and plugs and set the timing. That's it -- I never learned anything else about working on cars.Car engines -- they were a mystery to me.

So when I purchased my present '58 TR3, at age 67, three years ago, I did with a great deal of concern about how I would keep it running without having to haul it to a shop all the time. Confidence.... I had absolutely no confidence... but I wanted the car. A friend of mine, in his late 60s but someone who has worked on vintage cars for many years -- he owns 15 cars that he personally restored -- convinced me that almost anyone can learn to work on these cars if they try.

So, in my "golden years" (ha, ha) I began slowly to learn auto mechanics! (I now regret never having taken auto mechanics in high school!) The learning process has been very, very slow, but I keep at it. I haven't undertaken any engine overhauls (I had to let the shop do that), but I hope someday to try it. (In fact, my friend is going to put a new head on one of his cars this week and he has invited me to watch and help and learn.)

So far I have rebuilt my carburetors, fiddled around with my distributor, adjusted the valves, replaced a regulator, stopped leaks, done a lot of scraping and painting of the chassis, and a number of other small jobs. Recently, I had to retrieve a lost screw in my distributor...

But, like you, I think I now have a reliable car. This has been my goal: to be able to jump in the car at a moments notice and take a road trip around western Virginia. And, like you, I hesitate to say that it is absolutely reliable, because that is when something goes wrong. The best I dare say, when I get home from a road trip, is; "Well... nothing broke down and nothing fell off! Another good day on the road!"

This personal information is not very important, but I hope it will encourage others who might be hesitant to work on their cars (if this old geezer can learn, then they can also). And I hope folks who would like to own and drive these cars, but who are fearful or nervous about keeping them going, will get over it and take the leap. They won't be sorry.

And... I cannot emphasize it too much... the BCF is a great help.

 

[Mickey Richaud]

Great attitude and outlook, Ed! And you are absolutely right about the merits of this forum. At any age.

I started fiddling with cars in my teen years back in the mid sixties. Never trained, but fortunate to hang around a mechanic's shop and work in a foreign car parts store during college. (Yes, they had colleges back then!) Built my first engine (VW) under the watchful eye of said mechanic, and soon after, built another with some massaging to make it much more fun, relatively speaking of course.

Bottom line is that these cars are not nearly as mysterious as they sometimes seem. And if I've learned anything, it's that when in doubt, tackle the obvious and easy things first.

Now, whether I heed my own advice is another story!


Mickey

 

[Member 10617]

Mickey,

I wouldn't have believed it three years ago, but ... yes ... these cars are not that mysterious. But... they are full of surprises! Whenever something goes wrong now, I look on it as a challenge: man vs machine. Sometimes (perhaps eventually) man wins!

It sure beats some of the other ways people spend their time.

And, not to drag this on too long: There is a real satisfaction driving down the road and knowing (or at least thinking one knows) what is going on under the hood, and what might have to be done if something goes wrong. All most of my friends know about cars is that you put the key in the slot, turn it, and off you go.