After the slant stopped at night on a freeway 800 miles from home due to a rotor dragging on a distributor cap terminal and stripping the new distributor gear I decided to do quality checks on any new distributor cap in the future using the below jig.

The first cap I checked out had a .040" clearance at one terminal and ,015" clearance on the diametrically opposite terminal. Obviously .000" clearance would automatically have me return the cap back to the dealer for a different one. Too big a gap would also be grounds for rejection for a different reason. I have 6 used caps & a couple of new ones to do a survey to see what the industry is throwing out there.

Has anyone got a result of a survey they may have done?
Have you compared secondary coil wire voltage variations against clearances?

The jig requires three holes for checking out a terminal:
1) one for inserting feeler
2) one for adding lighting highlighting the terminal of interest
3) one for viewing

http://s296.photobucket.com/user/184pal ... ort=9&o=20

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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/

Good stuff. Sucks about the shredded distributor drive pinion.

Please let us know what specific brand(s) and model(s) of cap gave you grief. This is an issue I've been bellyaching about for a long time with regard to Echlin caps; the first instance I can find here on this board is over 12 years old, and it refers to a more-than-once experience I had with Echlin caps in the early 1990 - here's an eleven-year-old account of that incident. Echlin got bought by Standard Motor Products, and there's been a whole lot of other such merging in the industry, and older, lower-demand parts like Slant-6 distributor caps (or distributor caps in general, for that matter) are increasingly made as cheaply as possible on old tooling (never make back the $$ required for new tooling) and/or outsourced to, ahem, "low-cost countries".

It's probably still possible to get acceptable Slant-6 distributor caps on the open market. But even if not, there are enough stockpiles of good ones out there to last us all as long as we need. Heck, I've got much more of a stockpile myself than I'll ever use, so whoever wants a good quality, properly-made distributor cap "this time for sure", in your choice of colors, send me a PM!

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

I'll add a standard ch-410 to the survey.....lots of them but I see no Ch-410X readily avalable.
Is CH-410 without the X 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/

CH-410X went away in the last big shift of Standard's product range. Previously no suffx was regular, "T" was cheap (oops, scuze me, "value priced" garbage, and "X" was premium. Now "T" is still cheap crap, and no suffix incorporates ???some or all??? of the features previously reserved for "X" parts. So a blue CH-410 would be supposedly equivalent to the previous CH-410X, except made in Mexico instead of the YSM.

Other caps I'd like to see put through your test:

Airtex/Wells 5D1022A

United CC611X (looks a lot like the old Standard CH-403X, predecessor to the CH-410X)

Kemparts 1933X

I don't imagine you wanting to get into anything like statistical sample sizes, so it'd probably be a spot check to see if the particular caps you get are made properly. Would also be interesting, in a cap-compatibility kind of way, to see test results with the long-tip Echlin MO-3000 or Accel 130319 rotor (see here).

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

Echlin Combo #4 is the best of the bunch for the Echlin group.
Two interference between rotor and cap found using the Mopar rotor.
More to come as I get other caps.

Note the Echlin caps were picked up from Napa dealers across the US. starting in New England and going to Calif. in October. First across the upper part of the US, then down Rt 66, then back along lower part of US up thru NC and back to N.E. The boxes had the same part number however the printing was different fonts. All said made in Mexico. I may have been getting different lots based on the fact that several eccentricities were all in the same direction (ie #5 to #2 )on several caps but different on others.

The jig spotted minor interference impacting dist. gear and excess gaps impacting secondary voltages. I'll be measuring secondary voltage changes next for those caps.

Slant Six Distributor Cap Terminal To Rotor Tip Gaps
Table shows results with Exchlin MO3000 Rotor
CAP CAP# MAX GAP MIN GAP ECCENTRIC
Echlin MO 40 1 0.030 0.013 0.008
Echlin MO 40 2 0.038 0.010 0.014
Echlin MO 40 3 0.041 0.012 0.014
Echlin MO 40 4 0.022 0.017 0.002
Echlin MO 40 5 0.034 0.014 0.010
Echlin MO 40 6 0.038 0.008 0.015
Echlin MO 40 7 0.040 0.015 0.012
Echlin MO 40 8 0.032 0.015 0.008
Echlin MO 40 9 0.041 0.009 0.016
Echlin MO 40 10 0.030 0.025 0.003
STND CH-410 1 0.030 0.008 0.011
STND CH-403X 1 0.040 0.015 0.012
AIRTX 5D1022A 1 0.030 0.005 0.012
REMANUF Echlin 9 0.018 0.012 0.001


For Different Rotors measured:
Echlin MO 13 add .057 to all gaps
CARQUEST D147P add .056 to all gaps
MOPAR 1838516 subtract .008 to all gaps (interference fit on Echlin #6 & Standard #1)

All dimensions in inches

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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/

"Would also be interesting, in a cap-compatibility kind of way, to see test results with the long-tip Echlin MO-3000 or Accel 130319 rotor"

Have more caps and rotors in to test however here is the eye opening result of comparing secondary voltage for the largest gap to smallest gap rotor and cap combo.

Biggest Gap Combo: New Echlin MO 40 cap with new MO 13 Rotor with gaps of .089 to .114" (varying with plug terminal)......19,000 to 22,000 volts on coil wire.

Smallest Gap Combo: New Different Echlin MO 40 cap with new Mo 3000 Rotor with gaps of .018 to .022" .........6,000 to 9,000 volts on coil wire

Cap comparison (without involving rotor) change was .022 to .041 gap
Said another way the cap change was responsible for 25% of the variation.

All other parameters and equipment was kept a constant including operating RPM. Noticeable improvement in smoothness of exhaust with the better cap and rotor combo.

I'll add to above gap info as more caps and rotor are measured.

ps: already found a Bluestreak cao that the terminals did not reach down to the rotor tip consequently the spark is jumping up instead of out to the terminal. More need to be checked to see if this is typical.

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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/

Dan, check your PM's.

Thanks,
Rick

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

Yumpin' yiminy...that's a HUGE difference!

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

Added 3 more new caps to the above table:
1) Another almost decent Echlin (as far as eccentricity goes) (cap #10)
2) An Airtex Premium Cap (interference with OEM Chrysler rotor!!)
3) Standard Bluestreak from the old days

Although the sample size is small it's easy to see that quality control looks lacking for those brands?.....How good is good? Look perhaps to the Secondary Voltage for that answer?

My guess?.......you can get down to the kind of numbers seen in the HEI and Chrysler Electronic ignition comparison shown in the Sun Tester Report in the HEI How To Series:
!) Chrysler Electronic Ignition = 5000 Volts
2) HEI with .045 plug gaps = 10,000 volts

Points Ignition should be hovering slightly below the Chrysler Electronic Ignition numbers.

So let's take the lousy cap/rotor combo that gave us 22,000 volts and machine them using common bench tools to get it in line with the goal......

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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/

Added cap data to above table.

Cap added is previously tested cap and rotor that previously scored the absolute worst in the Secondary Voltage Test but this time it was re-manufactured to reflect a possible do-able goal......uniform .015 gap.

It's best to go crude on the machining so that anyone can do it using their own hand tools so the gaps actually ended up varying between .012 and .018.

The short Echlin M0-13 rotor was lengthened 3/32 so that it barely cleared the #9 Echlin cap terminal that had the largest gap. Then each terminal is machined to just clear the super extended rotor. Finally polished each to final size. Custom building each terminal essentially rules out the impacts of eccentricity.

THE RESULTS: Secondary Voltage dropped from the high of 22,000 volts before re-machining to a low 3500 to 5000 volts after re-machining.

The 2nd significant data is not in the table .........take the cap off the jig and turn it around 180 degrees to test for the leaning tower of pizza effect. Sure enough all the finely machined terminals now either had large gaps or the rotor interfered.

Said a different way it's possible the caps are not sitting straight upright on the distributor due to the excessive plastic tolerances? Under those circumstances a single step machine plunge cut could not be made accurately.....each terminal would have to be machined separately in order to hold a decent tolerance!!!

More caps of different varieties are to be tested however if there is excess gap on the first test of that cap variety I'll do no more tests for those since it's possible to consider the manufacturer is not doing quality control to catch the bad ones.

If anyone has an original worn out Chrysler cap from the 60's or early 70's it would be good to test that to see what original slants had for gaps. The center electrode can be missing, the cap could have carbon trails, etc..... anything that has terminals still in place should be good for what measurement data is needed......Secondary Voltage however is not a valid comparison on a used cap.

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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/

I think the "gold standard" cap/rotor to look at would be the ones Chrysler paid extra-careful attention to. The original '60-type Slant-6 cap 1889424, used with the standard Chrysler rotor 1838516, made ground-out problems especially in cold/wet conditions. They fixed this in '62 by releasing a service package 2448273 which contained a cap 2098765, a rotor 2098770, and a coil-to-cap cable with better-sealing boots on it. The cap's contacts were 2x (or more) wider than the ones in the original (and all current) caps, and the rotor tip was narrower and longer. A few years thereafter ('66 or so) the cap was superseded in phases by 2444690 -- same design but in an upgraded tan material with higher dielectric performance than the previous black phenolic. A fair number of these caps, both black and tan, have passed through my hands over the years; I've never set up a measuring jig like yours, but I've also never seen one of these caps ground visibly off-centre.

This cap and rotor were available in the aftermarket from NAPA as Echlin MO-6 and MO-7; they might also have been available from other aftermarket brands (Standard/BlueStreak is a guess, but I've never seen one). Here again, I've not seen one of these Echlin MO-6 caps ground visibly off-centre.

For '68, Chrysler reverted to the narrow cap contacts (though now in the tan material, p/n 2642986) and standard "fits everything we make the distributor for" rotor. My best guess is this was a cost-saving move more than anything.

I definitely have one of the 2444690 caps, new, on shelf.

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

Can you confirm if the Echlin MO6 cap have the double wide aluminum terminals?

Do the Chrysler 2444690 and 2098765 caps have aluminum terminals?

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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/

Yes, click the link I provided and see for yourself! It has not been available from NAPA for a very long time.
Yes. I have never seen a wide-terminal cap with other than aluminum terminals.

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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 the wider contacts would be a performance upgrade? Or is it only a help in the adverse conditions you mentioned?

Thanks

_________________
2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6