Silly points question

Discussion in '40- & 55-Series Tech' started by ken_79-fj40, Jul 12, 2005.

  1. ken_79-fj40

    ken_79-fj40

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    Last night I changed my points,condensor, and plugs in my 40. Someone along the way put a mallory centrifugal advance distributor in and took out the electronic setup. I would like to slap that person. Anyway, I gapped the points at .019. Last night it started hard, actually flooded. But once running it ran great. Then this morning ,same thing. Go to leave for lunch and it won't start. So I go to mallory's website and find my point gap should be .022. So I widen the gap a bit (a bit too much) and it fires up, but won't rev over 2 grand. I drive about a mile to napa, buy a feeler gauge (left mine on the workbench at home) and regap the points. Fires up, drives fine. I put the timing light on it, reset the timing, and now it's sputtering slightly under load in first.

    Question is: How do I hook up a dwell meter to check the dwell? I have searched and found lots of references to this, but nobody explains how to hook it up to the truck. I have my grandfather's old dwell meter, but no idea how to use it.
     
  2. theo

    theo

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    My dwell meter uses a black lead to vehicle ground and a red lead to the "-" terminal on the coil. Switchable between rpm and dwell. It's 25 years old.
     
  3. ken_79-fj40

    ken_79-fj40

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    I think it's a single point. It only has one set of points in it, not two like some V-8 mallory distributors i've seen. I can't seem to figure out what model number distributor it is. It has no vacuum advance, just mechanical. I think it was purchased from man-a-fre a few owners ago. It makes more sense to hook it to power and the negative side, but i've never used a dwell meter, hence the question.
     
  4. Cruiser_Nerd

    Cruiser_Nerd That 25 Guy. Moderator

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  5. theo

    theo

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    A normal place to get a tach signal is from the negative side of the coil, which is hot every time the points close. Tachometers (and dwell meters) are calibrated or switchable to divide by the number of cylinders. Current flows through the meter to ground.
     
  6. Cruiser_Nerd

    Cruiser_Nerd That 25 Guy. Moderator

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    Ken, hook it up the way Theo says, when I run into you sometime I'll explain how mine worked. :doh:
     
  7. dfmorse

    dfmorse

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    Delco maybe?

    Ken; I did the same to my '79 FJ40. It was a Man-A-Fre delco and I use it to drive a Jacob capacitive discharge unit. Been working great since about 1986.

    A timing light can not time these distributors because u can't see the ball in the window and the timing needs to be around 12-14 degrees BTDC. You set these distributors by ear. An almost quote from my instruction sheet says this:


    Let the engine idle at low speed and rotate distributor slowly clockwise (advance) until the engine begins to rough idle and then back off a little. Clamp distributor tight ... Drive around and see if there is any problems; u may have to retard a small amount if slow starts are evident..

    Point setting is 0.019 inches
    Dwell is 28-35

    I've never messured my dwell; just set it by ear. The distributor did [And does] help at high altitude, i.e. Denver, CO

    dfm
     
  8. Dianna

    Dianna

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    Delco... Uh Oh

    If you have a Delco dizzy (like I did) get it out! I was told my board members here that it's a ticking time bomb... the shaft wears and stops turning the oil pump destroying your engine! Find your original set up (Ebay, cruiserparts.net, etc) and put it back in the engine it was designed for!
     
  9. dfmorse

    dfmorse

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    If you have a Delco dizzy (like I did) get it out! I was told my board members here that it's a ticking time bomb... the shaft wears and stops turning the oil pump destroying your engine! Find your original set up (Ebay, cruiserparts.net, etc) and put it back in the engine it was designed for!



    Thanks Dianna;
    As a mater of fact, I'm working on that very project right now. A new dizzy is $675 from the dealer (whew); however, I'm doing a rebuild on my original and plan on reinstalling same.
     
  10. ken_79-fj40

    ken_79-fj40

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    This actually is a mallory distributor. It has a mallory tag right on the side. It's been in there quite a while from the looks of things. It's actually running OK now. But a few times yesterday I had a slight stumble below 2000 rpm in first gear only?? Last night I checked the point gap again, it's fine. Also checked my plug gap, perfect. I was pleased to see the plugs look perfect, I always remember this thing running way rich with the weber and having to change plugs all the time. Before I realized how my timing light worked I used to always run this thing at 14 degrees base timing at idle instead of 7. Perhaps that is why the plugs are no longer fouling? Does look like I could use a new cap and rotor though. Been about 18k since I've changed them. I tried cleaning the contacts with some 2000 grit sandpaper and I think I hurt things more than helped.

    But back to the dwell meter. I tried hooking it up a few different ways, and all I managed to do was stall the motor. The needle would swing before it would cut out though, so somethings happening. I tried first neg side of coil with red lead, then black lead to ground, stalled out. So I switched it red to ground, black to neg side of coil, still stalled. Then I tried it on the positive battery terminal both ways. Stalled then too. Maybe the meter's junk.

    Another related thing. Back when I first got this truck it had an accel super coil with no ballast resistor. That combined with the advanced timing really made the thing rip, but I would burn up condensors every few hundred miles. After putting in a resistor, then switching to a proper no-resistor coil I don't have the power it used to. Runs fine though. Would a pertronix provide that much more spark energy? It would obviously help starting, but I'm wondering about power. Looking at the plugs and thinking about cams has me second guessing my tbi 350 thoughts again.
     
  11. cardinal fang

    cardinal fang

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    Everytime these distributor questions come up, I have to shake my head at all the issues people have with these aftermarket 'fancy' setups. Spend hundreds of $$$ and people still have issues with one thing or another. 5 years ago I spent about $150 for a pertronix setup with a pertronix's coil. Installed it into my 1975 2F in my 1973 FJ40. I have not had one single prolbem with that setup. Not one. It uses the stock distributor, and eliminates the ballast resistor. Never any issues with points, because there are no points. If you have an engine newer than 1975, then you do have to use a pre 1975 distributor becuase of the design of the newer distributors shaft not having a machined ledge on the shaft to hold the sending unit for the pertronix's. Other than that it, is a no brainer.
     
  12. ken_79-fj40

    ken_79-fj40

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    Bill,

    Believe me, I wish this truck still had the original electronic setup in it. The mallory works fine....most of the time. If I can figure out what model number distributor this thing is I probably will just put a pertronix in it and forget about it. I would go back to stock, but i'm pretty sure my ignitor is toast. And my truck is desmogged and lots of the underhood wiring has been "modified" by the last few owners.
     
  13. Cruiser_Nerd

    Cruiser_Nerd That 25 Guy. Moderator

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    :D Maybe buy a new dwell meter, it'll have instructions. :D Even if you don't use it later for points, it's nice to have the tach.

    I ran a Mallory mechanical advance dual point for many years......it had power off idle (because the base timing had to be pretty advanced) and midrange but seemed to poop out on the highway. I'm not sure what Mallory has the centrifugal advance set for, but my guess is we probably don't see 1/2 the rpm's necessary to take advantage of it.

    Picking up a stock electronic setup is probably the way to go. ;) Before you buy a Pertronix for the Mallory I'd pull it. Have someone put it in a machine to tell you what, and when, the advance is happening so you can compare it to the original specs.
     
  14. coiled40gary

    coiled40gary

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    Sounds like your dwell meter is shorting out your ignition, don't use it.
    Setting the point gap with a feeler gage accomplishes the same thing.

    If you have the remnents of some other ignition connected or partially connected, remove it. You should have ignition supply to the ballest resistor, then to the + on the coil, - of the coil goes to the distributer where it is connected to the points and the condensor. Make sure that when the points are open, there is no short to ground, intermittent or otherwise.

    Use a timing light, set your initial advance at idle, rev it up and down a few times, watching your timing to see that it always returns to the same setting. If your advance or something is sticking, you need to fix that first.
    Use a dial-back timing light and record your advance at 500 rpm increments from idle to 3000 rpms. You should see a change in your advance some where in this ball park:
    1000 2
    1500 14
    2000 24
    2500 27
    3000 31
    To these numbers add your intial advance setting to compare to your readings. This will tell you if the advance mechanism is still working.

    If you ran the ignition without a ballast resistor, you may have damaged the coil as well as all those condensors. A damaged coil may show symptoms only after it heats up, and intermittently. Your ignition should work fine with 9 or 10 volts on the + terminal of the coil. Higher than that may cause the coil to heat up too much, and may cause the points to pit faster.

    There is no reason why a points ignition could not be made to work just fine.

    I will have to look through the file of receipts to be sure, but I think I paid $250 for a new '76 distributer from the Toyota dealer here a few years ago. They did give me a TLCA discount. The '76 is a points distributer. You can add an ignitor or aftermarket add on ignition if you don't want to adjust the point but once every two years or so, and have a good reliable, easily trouble shot and serviced distributer. With $25 worth of parts that fit in the corner of the glove box, you will never be stuck from an ignition failure again.

    gary
     
  15. ken_79-fj40

    ken_79-fj40

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    Actually I haven't really had any major issues with this ignition. I gapped the points wrong , and it made for a miserable day on tuesday. It's now working fine, except for the slight occasional stumble in first gear under load. I've still got a question regarding correct wiring of this setup. Currently I am running a coil that doesn't require a ballast resistor. So 12 volts to the positive side, neg side connected to the points. But when I was running the correct mallory resistor, one of the guys at man-a-fre told me to wire the resistor inline between the negative side of the coil and the points. Should it indeed be inline with the positive side of the coil?
     
  16. coiled40gary

    coiled40gary

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    The + side is the only place I've seen them connected.

    gary
     
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