akehurst89
Well-Known Member
I have never dart a points gap before. This is a Mallory dual point distributor, what should I set the gap at?
Dual point distributor question
- Thread starter akehurst89
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67Dart273
Well-Known Member
We need to know exactly what model Mallory. Some were a 4 lobe cam, some were an 8 lobe, and are different. I hated screwin' with Mallory 4- lobe, and if you get them wrong, every other cylinder is slightly out of time
akehurst89
Well-Known Member
i should get the distributor this coming friday i will let you know which it is. so the 8 lobe distributor is easier to set up than the 4 lobe?
akehurst89
Well-Known Member
I called mallory and its a 4 lobe distributor, what should that be set at and how do i set it up so it doesnt screw up the timing on the clyinders like you talked about? never set one up before so im kinda points illiterate.
67Dart273
Well-Known Member
OK, first, I can't find my old literature ( EDIT here
[ame]http://www.carid.com/images/mallory/info/catalogue.pdf[/ame]
Go to page 20, photo posted at bottom
There were two main diversions of 4 lobe distributors.
1---Pull off the cap and make SURE whether it is a 4 lobe or 8 lobe
2--If it is a 4 lobe, seriously consider going a different route. I believe Pertronix may make a module for these. However, the Mallory catalog no longer lists a dist. cap for them. (EDIT see second post below)
A--One type of 4 lobe / 8 cylinder was the "double life" which uses one set of points to fire 1/2 the engine cylinders, and the other set to fire the other half. In other words, the points alternate firing
B--Second type is "rev pole" which used a special coil, was supposed to be similar to the "du-coil" (dual coil) setup
Again, if you have either of these, consider getting something else
Here's the thing about a 4 lobe:
Ever tuned up a twin cylinder anything with two points? One set of points fires one cylinder, the other set fires the remaining cylinder. Changing dwell (point gap) also changes TIMING. This means that if you get the gap/ timing set on one cylinder, now you must set the other points so that the TIMING for the second cylinder is the same for the second cylinder as the first
The ONLY ways I know to get a 4 lobe dual-life set up properly is to either use a distributor machine, or "on the engine" do the following:
1---Determine which points fires no1 cylinder. Set the dwell/ gap on that cylinder, and "rough" in the second set. To set dwell on each set, you'll need to block the opposite set open with cardboard, and adjust them, then check "on the starter" for proper dwell
2--With everything "normalled up," set the timing on no1 cylinder at smooth idle for some specific number which you can duplicate and see well on the marks
3--Use a piston stop to "make" a temporary timing mark for a cylinder on the second set of points like say cylinder no 3. Make this mark just as you would for no1, except use no3 cylinder, and make a mark you can see with the timing light. Now check timing on that no3 cylinder with your made mark, and diddle with the gap on the second set of points until the timing on no3 is the same as what you set no1 to. DO NOT move the distributor during this process. Change ONLY the gap on the secondary set of points
4--Last, reset the timing to wherever you really want it to be on the no3 cylinder by rotating the distributor as per normal, and for good measure, re re re check no6 to be sure it matches no1
Sound like fun? Maybe when I was 26. Not when I'm 65
At the very bottom is a screen shot out of page 20 of the catalog
[ame]http://www.carid.com/images/mallory/info/catalogue.pdf[/ame]
Go to page 20, photo posted at bottom
There were two main diversions of 4 lobe distributors.
1---Pull off the cap and make SURE whether it is a 4 lobe or 8 lobe
2--If it is a 4 lobe, seriously consider going a different route. I believe Pertronix may make a module for these. However, the Mallory catalog no longer lists a dist. cap for them. (EDIT see second post below)
A--One type of 4 lobe / 8 cylinder was the "double life" which uses one set of points to fire 1/2 the engine cylinders, and the other set to fire the other half. In other words, the points alternate firing
B--Second type is "rev pole" which used a special coil, was supposed to be similar to the "du-coil" (dual coil) setup
Again, if you have either of these, consider getting something else
Here's the thing about a 4 lobe:
Ever tuned up a twin cylinder anything with two points? One set of points fires one cylinder, the other set fires the remaining cylinder. Changing dwell (point gap) also changes TIMING. This means that if you get the gap/ timing set on one cylinder, now you must set the other points so that the TIMING for the second cylinder is the same for the second cylinder as the first
The ONLY ways I know to get a 4 lobe dual-life set up properly is to either use a distributor machine, or "on the engine" do the following:
1---Determine which points fires no1 cylinder. Set the dwell/ gap on that cylinder, and "rough" in the second set. To set dwell on each set, you'll need to block the opposite set open with cardboard, and adjust them, then check "on the starter" for proper dwell
2--With everything "normalled up," set the timing on no1 cylinder at smooth idle for some specific number which you can duplicate and see well on the marks
3--Use a piston stop to "make" a temporary timing mark for a cylinder on the second set of points like say cylinder no 3. Make this mark just as you would for no1, except use no3 cylinder, and make a mark you can see with the timing light. Now check timing on that no3 cylinder with your made mark, and diddle with the gap on the second set of points until the timing on no3 is the same as what you set no1 to. DO NOT move the distributor during this process. Change ONLY the gap on the secondary set of points
4--Last, reset the timing to wherever you really want it to be on the no3 cylinder by rotating the distributor as per normal, and for good measure, re re re check no6 to be sure it matches no1
Sound like fun? Maybe when I was 26. Not when I'm 65
At the very bottom is a screen shot out of page 20 of the catalog
67Dart273
Well-Known Member
Found this at Moparts, might be a cap number
http://board.moparts.org/ubbthreads/showflat.php?Number=6378979
Echlin#MA5
Gawd help you if you think you want to use a Rev-Pol coil setup. The Rev-Pol and "Double Life" were essentially the same, the points were independent for the Rev-Pol and paralleled together for the Double life. Twin condensers for the Rev-Pol, only one needed for Double Life
I found these over at HAMB, a mix of the two
http://www.jalopyjournal.com/forum/showthread.php?t=111336
http://board.moparts.org/ubbthreads/showflat.php?Number=6378979
Echlin#MA5
Gawd help you if you think you want to use a Rev-Pol coil setup. The Rev-Pol and "Double Life" were essentially the same, the points were independent for the Rev-Pol and paralleled together for the Double life. Twin condensers for the Rev-Pol, only one needed for Double Life
I found these over at HAMB, a mix of the two
http://www.jalopyjournal.com/forum/showthread.php?t=111336
I have an NOS Dual Life for a slant and all this is the reason it's gettin a pertronix. lol
67Dart273
Well-Known Member
Oh, hell. I assumed the OP was talkin' about a V8, maybe his IS for a slant?
I hadn't thought of that. lol I was just throwin it out there since I have a dual life. and I mean NOS cap and ALL. Looks just like a magneto. Sittin right in the original box.
akehurst89
Well-Known Member
This is for a 340
67Dart273
Well-Known Member
So this is for sure a 4 lobe and not an 8 lobe cam? Photos?
akehurst89
Well-Known Member
I won't have the distributor for a couple days. Mallory just sent it to me. I will post photos as soon as I get the distributor. Didn't realize it was going to be this difficult to set haha.
67Dart273
Well-Known Member
Well wait is this a NEW distributor? That won't be a 4 lobe, then I bet.
I can't believe this "alternating fire" crap -- WTH is the advantage compared to a single-point?? My factory dual point distributor uses the pair of points to increase dwell (they are adjusted separately, but the dwell is overlapping on the same cylinder). If one pair burns out, it will run off the other, well enough to get you home. But on this "4 lobe" Mallory, you'd be running on 4 cylinders.... that just seems idiotic. I agree, I wouldn't even mess with it, if that's how it works.
But back to the original question -- if you don't understand how to set a point gap, you really have no business messing with a dual point system. Do yourself a favor and go electronic -- it works better anyway, and is way less hassle. The only reason to go dual points is old-school bragging rights, or concours scoring.
But back to the original question -- if you don't understand how to set a point gap, you really have no business messing with a dual point system. Do yourself a favor and go electronic -- it works better anyway, and is way less hassle. The only reason to go dual points is old-school bragging rights, or concours scoring.
67Dart273
Well-Known Member
Google up Mallory "double life" or "rev pol", and "du coil."
There were several issues that older systems tried to solve.
The idea of the 4 lobe (V-eight "double life" was just what the name implied--- Each set of points fires alternating cylinders, so each set only switches have as much as a single point V8. The same, however, is also true of 8 lobe dual point setups --one set closes the circuit, the other points opens the circuit, so each does "half" the work
This is only a guess, but I believe the origin of the "double life" was quite simply that many guys rejected the rev-pol and Mallory simply marketed the 4 lobe as the "double life." I REALLY have never sat down and studied the rev pol, and at my age, have no desire to.
The other problem was getting enough current and dwell time to get performance out of a coil. "Building" the magnetic field in a coil depends on LOTS of variables, but the biggest ones are----------
More current would help spark, but is hell on points, hence dual points of some sort
More current helps the coil build spark, so ANY system is better than single points
Dwell TIME is the amount of distributor rotation in degrees (or time) that the points are CLOSED. You cannot simply set V8 single points for more dwell, because this closes them up more, and they start arcing worse and worse as you close them up. There is a practical limit, which is why traditional V8 single points were 'averaged' at 28-32 degrees---a compromise between points life, wear, and dwell time, and probably other factors such as bounce.
The rev-pol and Du-coil systems took a different approach. In the case of the du-coil, a special distributor, cap and rotor, used 2 points, 2 condensers, and 2 coils. The cap and rotor was essentially firing 2-- 4 cylinder engines (V-eights hooked together. These were a real PITA and just as much trouble to set up. I've only messed with them about 4 times back in the 70's and have been perfectly happy to not ever see one again.
Because each coil only fired half as often, this gave you more time for "dwell" to build up the magnetic field in the coil.
You must remember that this is BEFORE any real decent electronic systems came out, and there were only a few truly HP coils -- the old old black rectangular Mallory, and the then -new great big finned Accel coil.
Du-coil from over at HAMB. Essentially 2 -- 4 cylinder ignitions in one distributor housing
http://www.jalopyjournal.com/forum/showthread.php?t=443192&highlight=titus
akehurst89
Well-Known Member
This is a brand new Mallory distributor. They shipped it to me yesterday.
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