I have done both lash methods. I can't tell the difference in running afterwards, so I do the static method since it is much less mess.

My favorite static lash variant, for about the last 10-15 yrs, is to look at the I and E valves that are OPEN, and then adjust the ones that are opposite those on the cam/firing order. So if 2 I is open, adjust 5 I. If 4 E is open, adjust 3 E. Then bump the starter (remote switch best) and look for the next 2 to come open, and adjust the opposite ones. Then you don't have to pay attention to marks on the damper and it will work with even the longest duration cams. I also do not trust specs in general (from factory or aftermarket) for tuning parameters like timing, cam advance, valve lash... ALL of my engines are modified, and that's the way I like it. For a stocker, stock spec lash works very well. Ign timing can be adjusted a bit either way to achieve desired driving parameters. For any aftermarket cam, you can bet a lot of money that the lash specs and degrees advance are NOT right and they never tested/optimized those. In general, advancing a performance cam by 4-6 deg relative to the cam company spec will work better across the RPM range, and usually lash 0.005" to 0.018" looser (yes, you read that right) will be better than the provided spec. I have run something like 10-15 performance cams and this is pretty universal in my experience.

A few cents from the SW VA Slant garage...
Lou

_________________
Home of Slant6-powered fun machines since 1988

Okay. I can create a new thread, but I'll post this here now, as this discussion is ongoing.

Just checked my advance specs.

TSM states:
Centrifugal Advance (converted to CRANK DEGREES, as I'm using a timing light, not a distributor machine):
1000 RPM ± 120 —————— 0°
1120 RPM ————————— 0-4°
2160 RPM ————————— 12-16°
5000 RPM ————————— 23° ± 2°

Starts @ 1100 RPM, Max of 23° @ 5000 RPM (about half that at about half the RPM).


Vacuum Advance (again in CRANK DEGREES):
6" ± 2" —————————— 0°
10.5" ——————————— 8° ± 2°
13" ———————————— 10.5° - 15° (13°± 2°)

Starts @ ~ 7", Max of ~13° @ 13".


My Actual Readings:
Centrifugal: "All-In" by 2000 RPM (I think around 1700), max advance about 8°
Vacuum (new SMP pot): Starts @ 4", Max of 12° @ 10.5",

Also, my advance at idle (vacuum disconnected, of course), even at "below idle" (~450 RPM), "jumps around" by ±3°.

SO, it looks to me like my centrifugal advance springs are shot (advance is uneven, or "loose" at low RPMs, reaches full advance too early, so is in full advance at lower RPMs than it should be), and my aftermarket replacement advance pot starts at about half the vacuum that it should (provides advance at greater acceleration / power levels), but provides about the same amount of advance that it should.

All told, both of these can put the engine in a "too-advanced" state under normal-use conditions, and may be contributing to my slight pinging, especially the mechanical advance.
I know that if I were building a hot rod, I'd want my mechanical to come all-in sooner, but this isn't a hot rod, and doesn't have high compression or a hot cam, so that's not a desirable condition.

I'm sure they make adjustable hot rod vacuum advance pots, and I could go that route, but both Dawson's and Arizona Parts list the correct MoPar units (2098209) for not-unreasonable prices. Of course, there are those who would recommend against half-century old rubber parts, even if they are "new."
Opinions?

As far as the springs, which seem to be the important part, nobody has them, and nothing lists them (MoPar # 2448260).
Is anyone familiar with whether there are aftermarket "Tune Your Distributor" springs available that are closer than what I've got?
Do V-8 springs interchange with the \6 springs?

I did completely disassemble, clean, and lubricate the distributor a few months ago, and it was clean and looked like new inside, so this isn't a "rust" or "dried-up grease" problem.

I suspect this engine will always be just a little bit "off" until I get the advance a bit closer to stock.

Thanks,

– Eric

edit: I forgot to convert the vacuum advance degrees to crank degrees.

edit edit: I forgot to convert the centrifugal advance degrees to crank degrees.
Good thing I'm not an accountant.

Okay, so ASSuming that I haven't gone completely off the reservation with my idea that my advance springs have lost their mojo, I've been looking for solutions.

Original springs are unavailable.

Springs DO interchange between \6s and V8s.

There are spring kits one can buy, although, obviously, they all cater to the hot rodder, who will want a faster advance curve, rather than a slower one.

Here are the available kits, near as I can tell:

FireCore Performance Standard Advance Curve Kit with Springs – Chrysler/Mopar CHR-SPRKT, $13

Mancini Racing Mopar Distributor Spring Kit FBOSK $23

Summit Racing Distributor Advance Kit SUM-850121 $14

Renegade Racing Components Distributor Advance Curve Kit P5153446 $16


Anyone use any of these? Anyone more familiar with one brand or another?

I've re-curved HEI and regular GM distributors, so this is not mysterious to me, I just want to have the greatest chance of buying the right product the first time.

Thanks,

– Eric

I think they probably are not. Not with that low mileage on your car; not unless someone's brutalized the distributor or something's come apart.
All the more reason to back off your initial timing.
Your present new pot might be adjustable, at that. Not too big a range of hex keys that will fit thru the vacuum nipple; try them out—inch and metric—and see if any of them will grab hold. If so, tighten.
A lot depends on how and where they were stored. A high-ozone location will wreck rubber, but without that something like the diaphragm in a vacuum pot can be just fine even after sitting on a shelf for decades.
I'll be surprised if your springs are broken. Also, there will be two part numbers for the two different springs.
Shape-size? Yes. Spring rate/exact configuration/calibration? Random.
If you didn't have any broken springs then, you probably don't now. That doesn't mean everything's ducky with the springs; you may have swapped the light/heavy springs such that they're no longer adjusted the way they started out. Andor, they might have never been correctly adjusted in the first place.

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

Fair assessment. I was surprised by how good the distributor looked inside. Thats reassuring.

It still does not explain the "faster" advance curve, though.
Which I did, and I didn't have any pinging on a few-mile, multi-hill drive tonight.

BUT, now that I retarded it a bit (and readjusted the idle speed and mixture), it's sometimes a bit balky on accelerating from low RPMs, like it bogs and stalls, or nearly so, even after increasing the idle speed to about 625.

I feel it needs a more leisurely centrifugal advance.

Worth a try, though, after several hours of cogitation, I think the vacuum advance is close enough to specs for practical purposes (I initially got riled up over it because of a failure to perform some basic arithmetic).

Thank you. That was exactly the sort of advice I was looking for.
As above, I'm relegating changes to the vacuum advance to the back burner, but I'll keep that in mind, and will probably buy a factory original unit, if only for purposes of originality (which is spelled "O-C-D").

I'm sure they're not broken. I'm just concerned they may have gotten weak. The timing curve I measured would certainly imply it.
But Chrysler does only list one single part number for them, as a set. They are not listed individually.

I never removed the springs from their posts, so if they've been swapped, it wusn't me that dun it.
I'm just concerned that they're weak. I've seen it with other vehicles (motorcycles), so I know it can happen.

Thanks as always, Dan. I'll keep you apprised as I work this out. And I will work it out.

– Eric

Misplaced or misadjusted springs would.
The carburetor's idle mixture and speed settings will need careful readjustment; they are interlinked with basic ignition timing. Also, carefully check the accelerator pump stroke.
I agree with you. The reason the FSM gives ranges rather than precise values is because we're talking about imprecise physical systems here with a great deal of imprecision and hysteresis and other forces that give old cars those "personalities" we're always jabbering about.
This is almost never seen even on very high-miles distributors. And really not likely with just 38 kilomiles. If you're looking for possible causes of jumpy timing at idle, check for timing chain slack. Again, not terribly likely with your low miles, but it's more likely than weak distributor springs. Also, keep in mind points-condenser ignition systems will tend to show a bit more timing jump-around at low RPM than electronic systems.
As a set makes sense, as an individual spring wouldn't have.

Alright, then…adjust them! This is done by bending the anchor tab toward (for looser/weaker/faster/at lower RPM) or away (for tighter/stronger/slower/at higher RPM) from the spring coil. It sounds like your lightweight primary spring wants a tighter adjustment.

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

I always adjust the speed and mixture screws together. Been doin' it since I wus knee-high to a Dachshund.

I set the accelerator pump stroke when I rebuilt the carburetor a few months ago, but I can double check it.

Good to know. Because they definitely can become weak on old BMW motorcycles.

And, yes, I am familiar with the fact that at low RPMs, small variations in timing can appear magnified (600 RPM = 300 sparks per minute on #1 Cylinder = 5 pulses per second = you can perceive each individual flash).
That being said, I haven't seen it to this extent in an ignition system where everything is otherwise well (I have seen it where something was loose, or where the vacuum advance was still connected and having influence).

Very helpful. I am not accustomed to all of Wally P's ways. You can't do that with the "other guys'" distributors.

I'll probably get a chance to mess with it again tomorrow.

Thanks,

– Eric

That centrifugal adv curve looks way off for a stock 63 dist. Normally for that era they have about 20-25 deg (crank) of advance swing for mech and 13-18 for vac. I wonder if you are actually posting numbers in cam/dist degrees, which would be about right. I have never seen a broken or weak spring. User bigslant6fan has dist recurve kits that are super nice, but he does not come on this site much anymore. I could ping him if you want one.

Lou

_________________
Home of Slant6-powered fun machines since 1988

Interesting.
Nope. I doubled all Distributor Degree values from the 1964 TSM to obtain Crank Degrees (after initially forgetting to double a couple of them... ).
Good to know.
I already PMed him.

Thanks!

– Eric

OK, I was reading the vac advance wrong. Yes, 13 crank deg is right.

I am baffled by the TSM spec for mechanical advance. It could be there is a bunch of advance from idle to 1000 RPM? I recall all the early dists had at least 20 deg swing (from experiments, not TSM). I always weld the slots up quite a bit to limit swing to 10-13 crank deg (mech advance, for perf cam use).

All Slants I have seen have 3 deg of advance wiggling at/near idle (and at many other RPMs). The timing chain and dist gear to cam gear usually have that much slop in them, even w/o much wear, and idle is where things are likely to be least stable.

Lou

_________________
Home of Slant6-powered fun machines since 1988

Me too.
I forget the exact number, and don't have the book with me now, but the TSM listed max advance at something like 2400 Distributor RPM, which is essentially 5000 RPM, which is faster than a stock \6 will ever spin.
Again, I don't have the book with me, but the advance spec really looked surprisingly linear to me.
Yeah, if I were hot rodding it, it would be different, but I'm trying to keep this one super original because it's so original now.
Good to know.
The last one I had was 20 years ago, and it was just a driver, so I have no recollection of how the advance marks looked.

Thanks, Lou!

- Eric

There is one lighter spring and one really heavy spring. The light one comes in by about 2000 (crank RPM), IIRC, and then the heavy one has a long slow advance to quite high RPM.

Lou

_________________
Home of Slant6-powered fun machines since 1988

For another point of reference, here are the '66 specs (225/automatic, without Clean Air Package). Offered here just to check for extreme divergence from the '64 specs—a misprint or whatever:

Centrifugal advance (crank degrees @ crank RPM):

0° @ 650 - 950
0 to 5° @ 950
15 to 19° @ 1920
21 to 25° @ 4400

Vaccum advance (crank degrees at inches of Mercury):

0° @ 4.9 to 7.1"
6 to 10° @ 10.5"
10.5 to 15° @ 13"

Also, read Doc's article on Slant-6 ignition tuning.

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

Thanks, Dan.

Your having posted that confirmed the "something's not right" feeling I had.
I went and confirmed your numbers in my own '66 TSM, then made a graph, which didn't look right.

Turns out that while I doubled the RPM and the Vacuum Advance degrees, I neglected to double the Centrifugal Advance Degrees.

Now when I graph the centrifugal advance between 1964 and 1966, the are almost identical ('66 actually advances a little bit more at higher RPMs).

Vacuum Advance specs are essentially identical, because they ARE identical – the same vacuum advance unit is spec'ed for both years.

I have corrected these numbers in my earlier post.

HOWEVER, all this really does for me is to make my measured centrifugal advance problem even worse.
I'm supposed to have a maximum of about 23 crank degrees advance, all-in by 5000 RPM, and about half-in by 2000 RPM (which is where the second spring would begin to act).
What I actually got was a maximum of about 8° before 2000 RPM, which is clearly way off.

I'll go down and re-measure, but it seems there's a spring issue.

Thanks,

– Eric

Alright, here's the latest on this:

I rechecked my numbers on the car (no change), then I removed and disassembled the distributor.
This time I removed the gear so I could see under the advance unit.
I did not pull the shaft completely out, as it was tight in the brass bushings and I didn't want to score them up, but I was able to reach and see under the weights.

The distributor is the correct 2444254 unit, with an R11.5 (11.5° distributor / 23° crank) advance unit.
Everything was clean and moved easily.
The weights just began to tug on the end of the large spring when they were nearly at the end of their slots.

So, I bent the tab for the large weight slightly, so that it began to make contact about halfway along the slot.

I re-lubed everything, reassembled, replaced, and retimed.

Now, the timing mark no longer judders or wanders around at idle, but everything else is the same.

Current centrifugal timing, assuming that an idle of 600 RPM is Zero, is:
1000 —— 5°
1500 —— 7.5°
2000—— ~15°

Above 2000 RPM, the line doesn't seem to advance at all. I went all the way to 4000 before I chickened out.
Above 2000 RPM the line does waver around a bit, though.

I did this with two different timing lights, and both read exactly the same, so it's not my timing light conking out as the revs rise.
(I use my Snap-On dial-back timing light to time my motorcycle, which is a wasted spark system, and she fires fine up to 4-5000 RPM, which is the equivalent of 8-10,000 RPM in a normal system).

So, what would make my clean, low-mileage, untampered 23° advance unit advance to only 15° total?

I have read that these motors "like" about 30° total advance (excluding vacuum), which would mean that for this unit I should set my timing to 15° BTDC.
I'm not going to do that, but I'm interested in opinions on this situation.

– Eric