Just installed Crank Trigger, no fire.

Discussion in 'PSI Superchargers Tech Questions' started by isracing, May 8, 2011.

Page 1 of 2
  1. isracing

    isracing New Member

    Joined:
    Oct 8, 2008
    Messages:
    130
    Likes Received:
    0
    I never ran a crank trigger before and just put a Lehey trigger on but the motor won't fire. I'm running a 16v battery setup, logger shows 17v on the battery. It runs fine with the trigger out of the picture, but if I connect it up the motor wont' fire. I closed the gap to .060 still nothing, have it indexed perfectly over the magnet for my timing (32*BTDC on the pointer, trigger centered over magnet) Set Ign timing on mag just fine.. just need to get it to run on the CT and set that timing. I was told by a fellow racer that I don't have enough RPM on startup, they used to have the same issue before swapping to 24v, they had to use a crossover switch to start on mag and switch to the trigger after it fired.

    Anybody have this same issue?
     
    #1
    isracing, May 8, 2011
  2. doug_ta

    doug_ta Member

    Joined:
    Nov 19, 2004
    Messages:
    78
    Likes Received:
    0
    The cranking speed needs to be at least 250 rpm. It'll be hard to achieve this even with 24V. I presume its an on-board starter, if it is, you'll need to change the reduction on the starter to increase the rpm. If it is a remote starter, just use 36V minimum and be done with it.

    Good luck,
    Doug
     
    #2
    doug_ta, May 9, 2011
  3. Mike Canter

    Mike Canter Top Dragster
    Staff Member

    Joined:
    Mar 10, 2004
    Messages:
    4,630
    Likes Received:
    189
    Check (carefully) to see if you have spark out of the coil wire. If it comes out of the coil but not out of the plug wires then it is a rotor phasing problem. If not then maybe a rpm issue but a lot of PMs use 16 volt batteries with great success.
     
    #3
    Mike Canter, May 9, 2011
  4. isracing

    isracing New Member

    Joined:
    Oct 8, 2008
    Messages:
    130
    Likes Received:
    0
    It is an onboard starter, SBC

    Mike, can you please explain rotor phasing?

    it's a ProMag 12lt
     
    #4
    isracing, May 9, 2011
  5. Mike Canter

    Mike Canter Top Dragster
    Staff Member

    Joined:
    Mar 10, 2004
    Messages:
    4,630
    Likes Received:
    189
    It is adjusting the rotation of the mag generator so that the rotor is pointed directly at the cap post when the crank trigger fires the generator. There are several ways to adjust this.

    1. Put the hub degree at the timing mark, say at 32*, adjust the crank trigger pickup so it is directly across from a magnet and turn the mag generator so the rotor is exactly opposite the cap #1 post. You have to be careful here because there is slack in the mag shaft so you want to turn the rotor by hand in the opposite direction of rotation so it lines up. This should get you very close.

    2. The other method is to run it off the mag with no crank trigger. Set the timing with a timing light so it is at (the example) 32*. Now stop the motor and put the pointer on 32* and adjust the crank trigger so the pickup is directly across from a magnet DO NOT TURN THE MAG. Now start it up and adjust the crank trigger so you are at 32* with a timing light. Now all should be phased.

    3. What I do from my nitrous daze is to get and old mag cap and drill a 3/8 hole through the cap directly inside of number one post. I put a dab of yellow or white paint on the lip of the hole exactly inline with number one post and a dab on the middile of the rotor so it can be seen through the hole. Start it up and adjust the crank trigger for 32* then shine the timing light through that hole and the two white marks should be lined up. If not I turn the mag until it is.

    I would start off with number one or two.
     
    #5
    Mike Canter, May 9, 2011
  6. isracing

    isracing New Member

    Joined:
    Oct 8, 2008
    Messages:
    130
    Likes Received:
    0
    Mike, I have done #2,

    When I drop my distributors I always set the crank at the desired timing (32* in this case) then drop the distributor with the rotor pointing directly at the #1 post. Have been doing this for years and never had an engine that didn't fire and be really close the first time it cranked over.

    Once I firied the car on the mag, I set the timing (was only off by 3* or so) I took off my lower pulley (to see the magnets) and sat under the car with a straight line of sight to the wheel and set the trigger dead nuts center of the magnet.

    Now I just talked to ProMag and was told that these lehey triggers have not been working on the MSD stuff, that Dave changed something inside with the wiring or circuitry or something that is causing problems. Their ProMag tech had one of these on the scope and the signal was funky compared to the MSD trigger...

    Left a message with Lehey waiting for a call back.

    I really hope this isn't the case, I would think that the lehey trigger is a very popular trigger among the pro ranks, and I would assume that 100% of the cars out there run MSD ignition... so why would the 2 not work together.
     
    #6
    isracing, May 9, 2011
  7. isracing

    isracing New Member

    Joined:
    Oct 8, 2008
    Messages:
    130
    Likes Received:
    0
    Now one thing I didn't do... (just spoke to MSD again) is when I set the crank back at 32* I didn't pull the cap or spark plug to make sure it was on the compression stroke and pointing at #1 cylinder. I just rotated the crank randomly back to 32* and set the trigger over a magnet.

    But....... shouldn't 32* be 32* regardless of if it's 180 off on the rotor or not? or should I pull the cap and make sure it's at #1 before checking the trigger.
     
    #7
    isracing, May 9, 2011
  8. clint thompson

    clint thompson Member

    Joined:
    Jan 15, 2004
    Messages:
    633
    Likes Received:
    4
    yes

    It will make a difference. You need to set the crank trigger on number one the same as you set the mag. That is likely what is causing you to be out of phase. As for the Leahy triggers, I have never heard that. I've never ran anything but a Leahy one. Probably used three in the past nine years.
     
    #8
    clint thompson, May 9, 2011
  9. Mike Canter

    Mike Canter Top Dragster
    Staff Member

    Joined:
    Mar 10, 2004
    Messages:
    4,630
    Likes Received:
    189
    Like I said before if you pull the coil wire out of the cap and hold it next to the block or chassis (I usually stick and old sparkplug in the end and lay it down on the black or chassis) and spin the motor over. If you see spark then the crank trigger is good and it is out of rotor phase or 180* out. If no spark then probably the crank trigger. Then hook up the mag without the crank trigger and test it again. If you have spark now then for sure the crank trigger is the cause. No guess work here.

    Isracing, if it is 180* then the rotor will be 180* out and it will not work. The timing mark and the cranktrigger magnets will be on but the rotor will be lined up exactly 180* out.
     
    #9
    Mike Canter, May 9, 2011
  10. Danny Humphreys

    Danny Humphreys Member

    Joined:
    Aug 4, 2003
    Messages:
    489
    Likes Received:
    0
    Leahy trigger

    Leahy triggers provde an EXTREMELY weak signal at low RPM's dont know why, but they do i've fought them before you definitely need good cranking speed with them try using gas to prime the motor and see if that helps, if so, you probably need more cranking speed
     
    #10
    Danny Humphreys, May 9, 2011
  11. isracing

    isracing New Member

    Joined:
    Oct 8, 2008
    Messages:
    130
    Likes Received:
    0
    I'm stil having trouble understanding this 180 off deal.

    If there are 4 magnets on the wheel, every 90*

    If I set the crank wheel to 32* BTDC, and have the trigger over a magnet... and the distributor pointing at #1, all is good right

    Now if the rotor is pointing at #6 which is 180 off... the wheel still has magnets every 90* wouldn't the crank trigger be just be pointing to the same magnet?

    if the crank pointer is at 32* (regardless of rotor at 1 or 6) and the trigger is on a magnet.... why should it matter if it's at 6 or 1 on the rotor. It sounds simple, but I'm having trouble grasping the concept.
     
    #11
    isracing, May 9, 2011
  12. Mike Canter

    Mike Canter Top Dragster
    Staff Member

    Joined:
    Mar 10, 2004
    Messages:
    4,630
    Likes Received:
    189
    There would be no problem with the crank trigger at 180* out. Read the last sentence in my last post above.
     
    #12
    Mike Canter, May 9, 2011
  13. isracing

    isracing New Member

    Joined:
    Oct 8, 2008
    Messages:
    130
    Likes Received:
    0


    Gotcha Mike, thanks for all the input... I think we're all on the same page now. Engine runs Great on the mag alone, just won't run at all on the trigger :(

    Leahy must be closed today, can't reach anybody... might order a MSD pickup as a backup plan
     
    #13
    isracing, May 9, 2011
  14. john348

    john348 Top Alcohol

    Joined:
    May 29, 2003
    Messages:
    1,348
    Likes Received:
    5
    put a crossover switch on it
    start on mag then go to trigger
     
    #14
    john348, May 9, 2011
  15. Mike Canter

    Mike Canter Top Dragster
    Staff Member

    Joined:
    Mar 10, 2004
    Messages:
    4,630
    Likes Received:
    189
    It may not be the crank trigger. Hook up the crank trigger and test the output of the coil like I stated above. It will tell you everything.
     
    #15
    Mike Canter, May 9, 2011
  16. isracing

    isracing New Member

    Joined:
    Oct 8, 2008
    Messages:
    130
    Likes Received:
    0
    Mike, so if I hook up a spark plug to the coil... ground it, and turn over the motor with A) the Mag hooked up normally, the plug should spark. And also do the same thing with the trigger hooked up, it should spark.

    Now if it doesn't spark on the trigger what does that tell us?
     
    #16
    isracing, May 9, 2011
  17. Mike Canter

    Mike Canter Top Dragster
    Staff Member

    Joined:
    Mar 10, 2004
    Messages:
    4,630
    Likes Received:
    189
    If it sparks through the plug on the coil wire coming out of the coil with the crank trigger hooked up means that the Leahy pickup is working just fine and it is most likely a rotor phasing problem. That is the easy part.

    If you get spark on the mag through the plug on the coil wire and do NOT get it through the coil wire plug when on the crank trigger then you have a crank trigger problem so you then need to double check how you have the crank trigger hooked up to the mag. If that is all hooked up correctly then you need to call Dave because most likely the pickup is bad. Is there any question on hooking the plugs up for the crank trigger to the mag?
     
    #17
    Mike Canter, May 9, 2011
  18. pop

    pop New Member

    Joined:
    Sep 12, 2003
    Messages:
    34
    Likes Received:
    0
    crank trigger

    try closing your air gap to30-40 thou if it starts your cranking speed is too low.
     
    #18
    pop, May 9, 2011
  19. GTPerf

    GTPerf Member

    Joined:
    Oct 22, 2006
    Messages:
    204
    Likes Received:
    5
    crank trigger

    I HAVE BEEN THROUGH THE SAME THING IF YOU ARE USEING A TIMING BOX LIKE AN 8973 YOU NEED TO SET THEM ABOUT 5,DEG DIFFERENT OR IT WILL NOT START CALL EM THEY WILL TELL YOU HOW I FORGET EXACTLY WITCH ONE BUT i THINK YOU PUT THE CRANK TRIGER 4 TO 5 DEG AHEAD OF THE MAG
     
    #19
    GTPerf, May 9, 2011
  20. orsoweld

    orsoweld New Member

    Joined:
    Dec 19, 2010
    Messages:
    42
    Likes Received:
    0
    thats what I do!!!!!!!!!!!
     
    #20
    orsoweld, May 9, 2011
Page 1 of 2

Share This Page





XenPorta 2 PRO © Jason Axelrod from 8WAYRUN.COM