Problem: With rotor pointing directly at #1 post the engine is firing about 25 deg. retarded

Said another way when the distributor is adjusted to fire at 8 deg. BTC the rotor is located halfway between #1 and #5.

Possible cause may be clocking of newly installed distributor gear?

My 65 FSM indicated alignment of the sloped distributor gear for a points distributor relative to the rotor tip is required such that the center of a gear sloped tooth must align with the rotor tip.* In my 75 distributor case it appears the gear is aligned halfway between two gear centers ....putting it an angle about 15 distributor deg. or about 30 engine deg. off of specs.

Does this logic sound reasonable?

Anyone can share a jig concept that gets the gear drilled to precisely match the FSM specs?

* FSM draws a straight line from rotor tip thru pin hole in gear and extends to the sloped gear center

ps: piston position at tdc verified damper marking still OK.

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1965 Dart 110k, 225, Carter BBD Super Six, 2 1/4 single exh., sbp manual scarebird front disc, 7 1/4 rear 2.94 sure grip, 14 x 4.5 OEM wheels, 833 OD with hyd. throwout bearing, HEI, electric fan, ram air/heated air, Accusump. http://plymouthcarclub.com/

What ign system do you have? Stock points, stock Mopar electronic, HEI conversion, or something else?

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Are you sure the timing mark on the vibration damper hasn't slipped?

So long as the distributor drive gear has a good contact pattern with the cam gear, the relation between the slope of the gear and the tip of the rotor is arbitrary. The reason why people redrill the down hole on replacement gears is to set the mesh depth of the distributor drive gear, The pre-drilled hole often isn't set to the right depth. Once you have the gear installed, just set your timing like normal.

Did you drill your new distributor drive pinion (the right way), or just use the hole it had (wrong way)? See this thread.

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

Rebuilt engine is in garage running on engine stand and I started with HEI and found the rotor between 1 & 5 post problem. Substituted a points distributor & std. coil and problem was gone with rotor directly pointing at #1 set at 8 BDC . This pointed to electronic distributor as the issue.
Besides the verification that the damper was right against piston position the std. points/coil results showed the damper and rotor position to agree at tdc when running. Unlikely the damper slips with Electronic distributor and doesn't slip with points distributor.
Gear was re-drilled clocked 90 deg from the incorrectly drilled hole and set to give .007 end play.,,,there lies the possible problem...giving relative position from a possible incorrect hole? Suppliers are constantly changing for many of the NAPA parts and anything can happen? (Using Napa Gear DG404 and just ordered 2 more to compare them straight out of the box)

I don't have a 75 FSM but here is the Figure showing proper clocking from my 65 FSM for a points distributor which I verified existed for the points distributor I used in the above test:

http://s296.photobucket.com/user/184pal ... 6.jpg.html

I was hoping someone had a 75 FSM or so and showed how a gear is suppose to be clocked for an electronic model.

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1965 Dart 110k, 225, Carter BBD Super Six, 2 1/4 single exh., sbp manual scarebird front disc, 7 1/4 rear 2.94 sure grip, 14 x 4.5 OEM wheels, 833 OD with hyd. throwout bearing, HEI, electric fan, ram air/heated air, Accusump. http://plymouthcarclub.com/

It is circular. Relation between the center of the rotor tip and the gears is irrelevant. Pertintent concerns are depth of the drive gear mesh to the cam gear and relation ship between the timing mark on the damper and true tdc. Use a piston stop tool to verify the timing mark and then install the gear to get proper mesh. Then just set your timing.

Suggest you test your theory by using this modified distributor cap:

http://s296.photobucket.com/user/184pal ... g.html?o=0

After bringing the timing in to where you want then set the crank position to 8 BTDC and put the modified cap in place of the existing cap. How close your rotor is to the plug wire connection measures how good your distributor is assembled.

I use the same cap when setting the distributor into the block....you will be shocked if you try several different distributors where the gear has been changed from good old factory original.

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1965 Dart 110k, 225, Carter BBD Super Six, 2 1/4 single exh., sbp manual scarebird front disc, 7 1/4 rear 2.94 sure grip, 14 x 4.5 OEM wheels, 833 OD with hyd. throwout bearing, HEI, electric fan, ram air/heated air, Accusump. http://plymouthcarclub.com/

Doesn't matter if the pinion is half a tooth, one tooth, two, three or four teeth different than what the old one or another one was. The distributor can be turned to set timing. If you have the older style clamp with the slot, and you run out of slot, you can pull the distributor and reinstall with the pinion one tooth, two teeth, three teeth whatever you need different than what it was. If you have the newer style clamp, no slot, you can turn the distributor as much as you want to get it where it needs to go. The important part is how the pinion meshes with the other gears, make sure it has the correct vertical tolerance, not too much vertical play.

Get it close to tower 1 (modified cap is a nice way to see where the button is relative to #1 tower, I do that too), then put the real cap on, start it up and adjust to proper spec by turning the distributor, check with timing light.

brian

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https://tinyurl.com/yynpj4v2

Actually the gear has nothing to do with rotor phasing. The position of he reluctor tooth to the pickup pole, and the position of the rotor on the shaft determines the phasing. If using HEI if the pickup wires are reversed the timing will be retarded, and the rotor phasing will be different, then if the wires were connected correctly. This is because of the way the module "sees" the waveform. I don't know if the Mopar electronic ign behaves the same way.
This suggests to me the pickup wires are revers of what they should be.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Put HEI distributor back in to test the above idea.
First set timing to 10btdc and checked rotor position with ECU wires left as they were. The rotor was off about 35 deg from plug tower with the engine stopped at 10 BTDC:

http://s296.photobucket.com/user/184pal ... sort=1&o=1

Then reversed ECU wires and restarted engine, adjusted timing back to 10 BTDC and rechecked rotor position with the ECU wire polarity change:

http://s296.photobucket.com/user/184pal ... sort=1&o=0

Big improvement. Getting the rotor slightly to the advanced side of the plug tower is done how? Right now the gap for the reluctor is set at .007 so where to go? The reluctor is pegged to the govenor shaft and the rotor fits in a govenor shaft slot. Modify the slot? Modify the cap slots and peg location?

Thanks for the ECU wire polarity phasing tip.

Don

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1965 Dart 110k, 225, Carter BBD Super Six, 2 1/4 single exh., sbp manual scarebird front disc, 7 1/4 rear 2.94 sure grip, 14 x 4.5 OEM wheels, 833 OD with hyd. throwout bearing, HEI, electric fan, ram air/heated air, Accusump. http://plymouthcarclub.com/

By rotating the distributor body.

If you don't have enough play in the hold down assembly, advance or retard the distributor gear one tooth as needed and then turn the distributor body.

I think DonPal meant to ask how to adjust the rotor-to-cap phasing without changing the ignition timing. Rotating the distributor body will change the ignition timing.

Richard Ehrenberg, editor of Mopar Action magazine, used to offer V8 reluctors with multiple keyways comparable to the multi-keyway camshaft sprockets used to dial-in cam timing. I think he stopped when his supply of cheap, good quality reluctors dried up, and anyhow he didn't offer 6-cylinder reluctors in the first place. But reluctors can still be had, and there's nothing stopping anyone else having a reluctor machined to spec.

That said, rotor-to-cap phasing isn't as big a deal on a six as on a V8, because there's more distance between adjacent cap terminals, which means less likelihood the spark will jump to the wrong terminal.

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

So expanding that thought perhaps there is a variation between reluctors and govenors as manufactured to specs with tolerances?

Although from a relativity standpoint the 6 is better than an 8, we went to the trouble of extending the rotor tip to minimize the gap between rotor and cap electrodes......angling the rotor away from the electrode must detract from any gain had by extending the rotor tip?

I'll try changing reluctors to see effect on rotor/cap electrode phasing with possible goals of improving parts life and spark intensity. Besides rotor position relative to the cap electrode it's possible to measure the spark intensity with the Sun Computer after changing the reluctor...maybe there will be no noticeable improvement but it's worth looking at just to determine effect of factory tolerances on reluctors.

Sun Computer needs to get base line for existing spark intensity with existing reluctor & maintaining all other variables constant like plug gap, etc. Plus a better picture of existing rotor phasing.

Then it's off to the distributor parts bin...........

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1965 Dart 110k, 225, Carter BBD Super Six, 2 1/4 single exh., sbp manual scarebird front disc, 7 1/4 rear 2.94 sure grip, 14 x 4.5 OEM wheels, 833 OD with hyd. throwout bearing, HEI, electric fan, ram air/heated air, Accusump. http://plymouthcarclub.com/

On further thought if the average person has 20 crank deg (10 dist deg) of mech advance for the case where the govenor is re-positioning the rotor relative to the cap then spliting that up 50/50 when the crank/ignition is set at 10 btdc may be the Mopar thinking?

So for that thinking the rotor would be about ideally positioned 5 deg after the plug tower when checked with the crank positioned 10 BTDC. Then when the mech advance is all in the rotor would be 5 dist deg before the plug tower.

Based on a rotor length of 1.5 inch from it's center that 5 dist. deg occurs when the rotor is 1/8 off center.

I drilled out my #1 plug cap electrode and viewed the rotor thru the opening to check for it's position......and it was close to the 1/8 retard offset.

I wonder if the vacuum advance enters into this line of thinking?

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1965 Dart 110k, 225, Carter BBD Super Six, 2 1/4 single exh., sbp manual scarebird front disc, 7 1/4 rear 2.94 sure grip, 14 x 4.5 OEM wheels, 833 OD with hyd. throwout bearing, HEI, electric fan, ram air/heated air, Accusump. http://plymouthcarclub.com/

Many years ago (a little over 3 decades ago, actually), in the oldest iteration of the Slant-6 News, a guy by the name of Myron Kuczmanski in New York advertised what he called a "plural ignition system" for the slant-6. It was a replacement reluctor with 18 splines as six groups of three. The idea, which was thoroughly faulty, was that this would create three sparks instead of just one per cylinder-fire event. It's the other piece of the "system" that's of interest: a rotor with a winged contact tip. It was winged only one direction: if you were looking from above at the installed rotor, the right edge of the contact tip was same as normal, but the left side was extended "counterclockwise".

Such rotor tips, usually winged in both directions, are common in numerous applications. It would be relatively not difficult to have some wide-tip rotor contacts made (or make one y'self, if you have a steady hand and a jigsaw and some patience). A small screwdriver can be used to carefully prise the original contact off the rotor body, and a bit of Loctite can be used to hold the rivet in place once reinstalled.

(And yes, it is very likely you'll find some variance in reluctor index pin/spline relationship).

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