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Using a Dual point distributor... What is the benefit?

Discussion in 'The Hokey Ass Message Board' started by chopperimpala, Jan 7, 2011.

  1. squirrel
    Joined: Sep 23, 2004
    Posts: 45,692

    squirrel
    Member

    ....it looks right.

    And it's possible that it might run a bit better at higher rpm, since you can get a bit more dwell out of it than you can with single points.

    [​IMG]
     
    Moriarity and Paul like this.
  2. town sedan
    Joined: Aug 18, 2011
    Posts: 1,290

    town sedan
    ALLIANCE MEMBER

    My 2 cents. A dual point distributor can make a nice noise, almost musical in nature and fits in well with the sewing machine sound solid lifters make. So, it's more than performance it's rock and or roll!
    -Dave
     
    Last edited: Jul 7, 2015
  3. Remcolent
    Joined: Jun 29, 2015
    Posts: 16

    Remcolent
    Member

    The 392 came standard with dual point , just to get more dwell, and so a better spark.
    It was nice in the 50,s but I think that a simple MSD 6a box will give way better spark with a lot less hassle
     
    tb33anda3rd likes this.
  4. MUNCIE
    Joined: Jan 24, 2006
    Posts: 2,224

    MUNCIE
    Member

    Yeah I thought about getting a unilite for my little 260, with additional ballastor and power filter but add the additional cost for those parts and add a coil into the mix and the price rises up to almost $400 :eek:. So I figured if the dual points distributor performed just as well I don't mind setting my points and saving a little cash while I'm at it.
     
  5. GMC BUBBA
    Joined: Jun 15, 2006
    Posts: 3,384

    GMC BUBBA
    Member

    The dual point adds some rpm band to the engine from the stock distributor. Stock may be 5500 to 6000 and the dual point may offer 6000 to 8000. Advance may be closer tailered to performance that the stock as well. Got one ? Why not run it , make you feel better as well..
     
  6. Rusty O'Toole
    Joined: Sep 17, 2006
    Posts: 9,106

    Rusty O'Toole
    Member

    They also extend point life by spreading the wear between 2 sets of points. Chryslers came stock with dual point distributors in the fifties, possibly other makes used them as well. They had vacuum and centrifugal advance.
     
  7. Most of the posters point out the increase in dwell improved spark and increase in rev range are all soundly based comments. I have been running a Mallory twin pointer on my midget which is an off road competition car which I use for hillclimbing. Over the time I have been running it , the last two years, I have had to come to grips with the quirks and limits of the twin point distributor. I overhauled it to remove slop and wear at various locations internally, cleaned up the points and fitted new condenser. I decided to upgrade the coil to a modern high performance coil. Seemed to me to be a sensible idea. I fitted a MSD2 Blaster coil which looks like a standard canister coil that have been with us for decades.This is a low resistance coil (.6 ohms). The manufacturer of the coil advises that you need to run a ballast resistor with it on a points type distributor. Plugs were set at 0.040" gap. Despite this I found that after each meeting the performance started to drop off. Each meeting involved 7-8 runs up a fixed course of about 800 yards and a return road of similar length. To my surprise the points were deteriorating (burning) and needed cleaning and resetting. No problem except that this all gets very time consuming. After tiring of all of that I fitted a Pertronix II conversion to dispense with the points. This permitted the use of the coil without the ballast and allows the maximum potential of the coil to be realised. I opened the plug gap up to .050" and as soon as I started it, (it fired on first hit of the starter button) it ran so much sharper and smoother than before. Whilst this is a track car all of this translates to the street. My essential point is that whilst those old twin pointers functioned well in their day, with all of the modern electronics there are greater efficiencies and performance to be gained. Despite being a fan of the traditional points and condenser for years you can do better these days and the beauty of these conversions you can't really see anything different.
     
    Last edited: Jul 7, 2015
  8. aaggie
    Joined: Nov 21, 2009
    Posts: 2,529

    aaggie
    ALLIANCE MEMBER

    In the '60s I ran a Rochester injected 301 SBC and out of necessity I had to use the dual point distributor to run the injection pump. Setting the points drill went like this: adjust the rough point gap to .016" and place a small piece of plastic shim stock between the other set of points. Fire it up warm and set the timing and dwell to 30#. Now shift the shim stock to the other set of points and repeat. Now remove the shim stock and check timing and check dwell.
    I heard of a guy that just put the second shim in place then followed his wife's order to get it here now and eat Supper and when he came back to finish up it took over an hour to figure out why there was no spark.
     
  9. Jimmy2car
    Joined: Nov 26, 2003
    Posts: 1,707

    Jimmy2car
    Member
    from No. Cal

    I don't think there is any advantage to a dual point distributor. Those days are long passed.
    The dual point was a big deal when 6 volts was the norm, allowing higher rpm when used as a dual coil, dual point device.
    Electronics are the norm now with great reliability and rpm potential
     
  10. MUNCIE
    Joined: Jan 24, 2006
    Posts: 2,224

    MUNCIE
    Member

    Appreciate everyone's advice and input. I guess I'm just looking to make small upgrades that won't cost me too much and improve performance with the 260. I'm don't think Mallory offers a single point distributor for the sbf.
    Also looking to eventually run a smaller carb, seems that the 600 CFM is just a tad too large but that's another story.
     
  11. pitman
    Joined: May 14, 2006
    Posts: 4,899

    pitman
    Member
    from Hampsha

    The 355 SBC in my avatar ran fine w/a Mallory up to ~6500 at 1/4 mile runs.
     
    Last edited: Jul 8, 2015
  12. gas & guns
    Joined: Feb 6, 2014
    Posts: 370

    gas & guns
    Member

    Haven't used points since high school. Most the guys I remember that had dual points back then, probably didn't set em up right or didn't need them anyway ( shifting at 6000 or less). I ran a single point distributor. We throw in a set of new points, close the cap and start it up. Open the window (Chevy) install your Allen wrench, turn one way till misfire, back the other way till misfire, set it in the middle. Crack the throttle a couple times to see what it sounded like and then set timing. Again, these were motors that were pretty much out of their power band after 6000 rpm anyway.
     
  13. squirrel
    Joined: Sep 23, 2004
    Posts: 45,692

    squirrel
    Member

    Yeah...but still, you know those stinky newfangled transistors are in there...it would drive me nuts.

    :)
     
    stik70 and Moriarity like this.
  14. indyjps
    Joined: Feb 21, 2007
    Posts: 3,760

    indyjps
    Member

    I ran a Mallory dual point in a 355 bowtie heads, comp 292 magnum cam, tuned it weekly, ran well. Switched to a unilite and picked up 2 tenths the next weekend. Maybe I'm not the best dual point tuner in the world, but it made me a believer, and I wasn't screwing with it all the time.
    Traded the distributor for an intake and never looked back.
    Pertronics came out a few years later, swapped them into the 2 vehicles in the family that had points.
     
  15. MUNCIE
    Joined: Jan 24, 2006
    Posts: 2,224

    MUNCIE
    Member

    Well I called Summit yesterday to gather some details after learning on the web that the dual point/unilite was listed as unavailable. Doesn't sound good gentleman, currently they are not sure if MSD has any plans on re-stocking them with additional dual point unilites. For now looks like my only option would be to go the other route, wih the additional ballast and ignition filter.
     
  16. GMC BUBBA
    Joined: Jun 15, 2006
    Posts: 3,384

    GMC BUBBA
    Member

    You may be over thinking the issue.
    Ford used to publish a Ford Parts Muscle book and manual that list performance improvements in stages like stage 1, 2,3 etc.
    Stage one was a major ignition tune up and distributor curve , usually added like 10-12 hp. Good quality parts ( heavy duty) proper spark plugs , timing set and distributor curved for the application.
    Dual point was after a camshaft change etc.
    I would suggest finding a vintage Mallory dual point ( can be made electronic) rebuilding it and adding solid core wires etc. Performance is great and cant beat the look......
    My friend Jerry held the National Record in J stock with a ford fairlane and 260 ci engine for years with a factory ford distributor..........
     
  17. GMC BUBBA
    Joined: Jun 15, 2006
    Posts: 3,384

    GMC BUBBA
    Member

  18. Rusty O'Toole
    Joined: Sep 17, 2006
    Posts: 9,106

    Rusty O'Toole
    Member

    If your points are burning you need a different condenser. Either the old one is shot, or if it is a modified ignition, you need one sized for your coil.
     
  19. MUNCIE
    Joined: Jan 24, 2006
    Posts: 2,224

    MUNCIE
    Member

    Rusty,
    Points are fine, no excessive wear. Just wanting to add a little pep to the 260 and improve some throttle response.Plans for a bettter ignition system and smaller carb (500 cfm) for now.
    Regards,
    Mark
     
  20. MUNCIE
    Joined: Jan 24, 2006
    Posts: 2,224

    MUNCIE
    Member

    Bubba,
    Thanks for the advice and tip on ebay. Thats what I am basically trying to achieve a little better spark and timing.With eventually better throttle response with a smaller carb.
    -Mark
     
  21. Rusty O'Toole
    Joined: Sep 17, 2006
    Posts: 9,106

    Rusty O'Toole
    Member

    I was referring to fredeuce's post above.
     
  22. MUNCIE
    Joined: Jan 24, 2006
    Posts: 2,224

    MUNCIE
    Member

    Oh, I didn't realize.
    Thanks
     
  23. nwbhotrod
    Joined: Oct 13, 2009
    Posts: 1,246

    nwbhotrod
    Member
    from wash state

    What it boils down to they just look kool
     
  24. As stated in my post I fitted a new condenser. To up the capacitance to remedy the problem was certainly an option however that would have entailed some trial and error experimentation.
    Knowing that the coil was best suited to an electronic/pointless system to extract its full potential , I figured it was time to change up and I have to say I am glad I did.
     
    Last edited: Jul 11, 2015
  25. indyjps
    Joined: Feb 21, 2007
    Posts: 3,760

    indyjps
    Member

    If your single point distributor is in good shape, no slop etc, just swap a Pertronics into it

    Or send it to Bubba and he'll dial it in for you.

    Only reason I went to a unilite was clearance and it was before pertronix.
     
  26. Resurrection of a Zombie thread.
    It is my understanding dual points wired together increase the coil saturation time and split by half the burning from switching the high amp load. Would agree with most that modern electronic ignition usually spark better and provides less labor opportunities. However from my experience with Chrysler factory electronic ignitions, you should always carry a spare control box and ballast resistor. While the pickup in the distributor rarely goes bad, if it does, you are stuck on the side of the road with hands in your pockets awaiting the tow. That is one thing that puts me off aftermarket triggered replacements like listed. Picture yourself in Resume Speed, SD on a Sunday afternoon.
    Have a single point Delco ignition in 153cid Chevy II engine triggering a cheap antique Capacitive Discharge box. Most of the benefits of modern ignition with the fallback failsafe of swapping some wires and driving home on just the old fashioned point style. Delta Mark 10 was good enough for Baldwin-Motion, is good enough for me. On upcoming V8 project, plan to wire each set of dual points to separate CD boxes. As mentioned earlier, one set will open slightly before the other, so can switch between for advanced or retard with N2O. Either will be redundant and get you home, all for less money than a modern replacement.
     

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