Topic: MAXI-DWELL?

[DH]

Anyone elaborate on these? The seller says they're better than electronic ignition, and will even replace electronic systems in some instances.......Ebay item #250944039877...I'd post a link, but don't know how sorry bou that. Very curious..

[754]

 nice pic of PAM in your avatar  !!

 I liked the maxi, even had a timing light on it.. ran good revved to 11K no problems with Andrews or stock coils.. points are at any Napa dealer... will take a long while till they need changing..

[MRieck]

http://www.ebay.com/itm/250944039877?ru=http%3A%2F%2Fwww.ebay.com%3A80%2Fsch%2Fi.html%3F_from%3DR40%26_trksid%3Dp5197.m570.l1313%26_nkw%3D250944039877%26_sacat%3DSee-All-Categories%26_fvi%3D1&_rdc=1

[754]

  I have a theory, it may or may not be correct..

 Honda points are very short, I believe this was to fit in the small confines on the smaller motors.
 At any rate, I think the Honda style points travel through a greater arc, in use, than the Delco style used in v-8s and the MAXI.

 This in itself greatly reduces the lifespan of the points being near the specs they were set at, and increases overall wear..

[chewbacca5000]

If you can get it cheap enough it might be worth a shot.  It might be better than than the electronic ignitions at the time.  I really like what 754 has to say, "ran good revved to 11K no problems with Andrews or stock coils."  Revved to 11k is very impressive!  If you do get it be sure to do a follow up post and let us know how it goes for you.  I am working on adapting the HEI / GM coil mod for a CB750 so I am interested to know what kind of performance GM points can give you.

[DH]

I guess my question mainly is, does the design of this set up actually increase coil saturation time enough to result in a hotter spark? They don't advertise a dwell spec, only that "when timing is correct, so is the dwell" or something to that effect. There's a "Buy it now" option for it at 115.00 in case anyone else is interested. I'm not in the market for a new ignition right now, but was just throwin this out there for compairison sake, and to learn from users in the past.
And yeah 754, that is a good pic of "Jungle Pam". Aint they all?

[TwoTired]

I guess my question mainly is, does the design of this set up actually increase coil saturation time enough to result in a hotter spark?

Not if they use the same points cam and point gap.
Do you/they have specs for those?

What coils will you use?

[TwoTired]

And, why is it you feel the need for a "hotter spark"?

[754]

 I prefer the "front shots", over the "back shots" of Pam..

 This is what I remember about Maxi-Dwell, I am glad they offer them again.
 GM points, but the better version used in Corvettes.
 Solid state condensers , smaller than a chicklet the pair of them.
 Built in timing light, not always easy to see but handy.

 A possible drawback, one set of points is set by moving the plate, the second by changing gap slightly.. but it worked fine.' And the points were riveted on, to change you remove rivets and bolt on.. and one set of points needs base ground off on one corner to fit. IK nevber ran an electronic ignition so cannot compare the two systems.
 At one pont  I sold my chopper but kept the motor and put it back in my 73 frame, my Andrews coils went with the chopper. I put stockers on, and thought I would feel a bit of difference.. but really couldnt tell..
 Although my motor sat for about ten years on and off sometimes for a few years at a time, the condensers were never changed

[72500john]

sounds interesting but i am leaning toward the hondaman ignition sytem..check it out on this web page. always went by the the if it aint broke dont fix it saying..but if you can relibly improve it it by all means go for it!

[DH]

And, why is it you feel the need for a "hotter spark"?

I don't. I only ask out of curiousity as to weather that set up offered that advantage, for say, maybe some high performance engine mods or just a little over kill to ensure easier starting, etc.
Sounds like low maintenance is the main advantage.

[DH]

I prefer the "front shots", over the "back shots" of Pam..

 This is what I remember about Maxi-Dwell, I am glad they offer them again.
 GM points, but the better version used in Corvettes.
 Solid state condensers , smaller than a chicklet the pair of them.
 Built in timing light, not always easy to see but handy.

 A possible drawback, one set of points is set by moving the plate, the second by changing gap slightly.. but it worked fine.' And the points were riveted on, to change you remove rivets and bolt on.. and one set of points needs base ground off on one corner to fit. IK nevber ran an electronic ignition so cannot compare the two systems.
 At one pont  I sold my chopper but kept the motor and put it back in my 73 frame, my Andrews coils went with the chopper. I put stockers on, and thought I would feel a bit of difference.. but really couldnt tell..
 Although my motor sat for about ten years on and off sometimes for a few years at a time, the condensers were never changed

Thanks for that 754. I remember the high perf points sets for G.M.s
A few others like the GTOs took them as well. I guess timing for the second set of points is by slightly "manipulating" dwell a bit
for the 2/3 cyls? Seems like the older mopar distributors worked kind of like that? Wouldn't that make coil saturation time slightly different between the coils ( not that it would make a huge difference)...Just curious is all.

[cben750f0]

watching

=)

peace

[dave500]

we had chevys here,and holdens with factory fitted chev engines,,those points would be pretty hard to find here unless you knew where and expensive,,that max dwell is really only a decent point set and capacitor upgrade?im sure it works well,the vented points were bull #$%* anyway(they attract negative ions?),back in the day i have replaced so many almost fused together,even replacing the capacitor as a matter of course,MAXI DWELL,,whats in a name?less dwell is sometimes desirable.

[w1sa]

There is no meaningful extra dwell to be had, just by changing a points plate set-up to a different points plate set-up.

[dave500]

you can trigger a few automotive ignition modules from the points for not much money,capable of firing much less resistance coils,with a tidy small installation,im now switching(via a transistor) to oil thread mode.

[chewbacca5000]

Dave,

I'd really like to know which automotive ignition modules can be triggered by points. How low of a resistance can you go?

Thanks!

[754]

 I think that the longer the distance between pivot and rubbing block, the longer the points will last.. also less chance of bounce.
 Email them, and ask about the extra dwell , let them explain it..

 I would run them again.. still got minde..

[TwoTired]

I think that the longer the distance between pivot and rubbing block, the longer the points will last..

I don't believe the trigonometry supports that.  I assume we are discussing the same cam lobe profile for both point sets?

A longer arm set at the same gap would open and close slower at the end allowing more time to "dally" during opening and closure where "partial contact" increases heating of the point material.

also less chance of bounce.

I can't believe that.  The slower contact speed would reduce collision impact force and the rebound effect from colliding metal components.  Less bounce would mean less time where the points are in the region of partial contact.

The stock point sets were good to well beyond valve float RPM.  Perhaps with engine mods, you may need 11K RPM ability (which you can get with simply double springing the stock points).  More likely, is that if you've spent time and money on the engine to "need" 11K capability, you will also go for a points substitution device.  Especially at $100 replacement cost.
http://www.recycler.com/details/4182798/maxi-dwell-ignition-honda

Unless, you are changing the point gap or point cam timing and lift profile.  It would seem the Chevy points are more hype and marketing than real science. imo

Haven't there been prior threads about the Maxi-dwell?  ...yes...
http://forums.sohc4.net/index.php?topic=31466.msg324369#msg324369

[754]

 I am not good with ignition theory,
 but if the arm was longer , and the points open/close slower, you get more dwell.. is this correct ?

 How many times doe the GM Delco points set open and close in a minute on a V-8 ??.. am thinking far more than on a Honda 4 .

 let may say this, started running the Maxi on a stock motor, added bore kit, and cam, it revved to themoon, cleanly... did not make me feel I was lacking anything in the ignition area..

[TwoTired]

I am not good with ignition theory,
 but if the arm was longer , and the points open/close slower, you get more dwell.. is this correct ?

Not really.  Dwell is defined as the duration of crank angle while the points remain closed.  It is the coil saturation time where the coil is charged up and energy stored for the next spark event.
The point cam determines this.  If you set the gap at max crown of the point cam, then rotate the plate so the points open at the timing mark, then the timing and dwell would be the same for any set of points, as they will close when the point cam profile determines, as well as open.

Does the Maxi dwell specify a different opening gap while at the max point of cam?

[DH]

I am not good with ignition theory,
 but if the arm was longer , and the points open/close slower, you get more dwell.. is this correct ?

Not really.  Dwell is defined as the duration of crank angle while the points remain closed.  It is the coil saturation time where the coil is charged up and energy stored for the next spark event.
The point cam determines this.  If you set the gap at max crown of the point cam, then rotate the plate so the points open at the timing mark, then the timing and dwell would be the same for any set of points, as they will close when the point cam profile determines, as well as open.

Does the Maxi dwell specify a different opening gap while at the max point of cam?

That's the thing T.T., the seller of the maxi dwell says that "dwell (gap, right?) "is pre set". when timing is correct, so is dwell. looks like to know what dwell really is with this set up would require actually measuring after installing the thing. That's why I asked if more dwell was "built in" to the design somehow. Sorry if I'm talking in a circle..

[dave500]

chewbacca5000,you can find all that info on the net.

[754]

 I think it is .020 gap...

[TwoTired]

I think it is .020 gap...

The Honda points cam supplies 195 degrees of dwell for the stock points gapped at .014" while at the cam lobe peak.  The lobe ramp position is then adjusted so that the points open at the specified time and then close 195 degrees later by cam lobe design profile.  If the gap is smaller, then the dwell or point closure time increases.  If the gap is larger, then the dwell time diminishes.

A larger gap changes the angle or distance between the cam ramp up and ramp down on the cam profile.  A larger gap closes later as it uses more of the cam ramp down, and then opens sooner as it encounters the ramp going up.  This diminishes dwell time.

Please note that the points and cam are part of a greater ignition system.
So, you can't simply look at dwell in isolation from the coils, which can be made or wound differently.  For example, low ohm coils charge much faster (drawing more current/power to do so), and may not even need to fully saturate before storing enough energy for the spark event  The spark gap and atmosphere between the electrodes determines the actual voltage needed to create the arc.  The coil secondary resistance determines how fast the coil can be discharged.  The dwell time is nearly unimportant at low RPM, as there is plenty of time between spark events to recharge the coil.  It is at High RPMs where the event durations become "interesting", because there is less time available to charge the coil back up before the next discharge event.

Each coil design will have an optimum saturation point and will not fully discharge as the spark event and current flow only last as long as the spark gap(s) has enough voltage to sustain the arc.

Other factors also come into play then, such as spark gap distance (larger gaps need more voltage to create the conductive arc), and added resistance in the coil output which can serve to limit the coil discharge depth.  The depth of coil discharge is then interactive with the charge time requirement or dwell of the next charge event. 

Hope this helps,