Power Grid Main Timing

Discussion in 'Manton Push Rods Top Alcohol Tech Questions' started by Adam2833, Mar 3, 2019.

  1. Adam2833

    Adam2833 New Member

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    Hi,
    Quick question about the main timing on the power grid.
    With no retards being used does the main timing value entered into the grid actually matter?
    It will still fire where the crank trigger is set at?

    We have a blown alcohol kb hemi Top Sportsman style car. Pro mag 44 and grid with leahy crank trigger.
    We are wanting to run base timing only while we learn this combination.

    We ran for the first time mid last year and ran out of time to get the smarter guys helping me to double check how the grid was setup. The launch wire wasn't even hooked up.
    The car fired and ran properly through the mag only and then fired and ran through the grid.
    First attempt at a full pass the belt shredded a piece off which took out the connector between the mag and points box. This was repaired but wouldn't re-fire on the grid. Switched back to mag only and fired and made another pass.
    I later found the earth for the crank trigger had also been broken which we figured caused the issue through the grid.
    Everything was re-wired and moved to better protect the wiring and tried to re-fire this weekend.
    Fired correctly on mag only with the grid hooked up. Changed the plug over to the grid and wouldn't fire.
    We have gone through the wiring and continuity and power checked everything we can think of.
    I can download the grid from running on the mag only and the timing in / out has a signal and looks correct and cranking rpm is 460, nothing was changed in the grid program from when it previously ran through it, but the main timing is actually set at 40 degrees.
    Thanks
     
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  2. Mike Canter

    Mike Canter Top Dragster
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    If on the Grid you have no retards then what you see with the timing light is what you get. So to make sure I have this straight. The car fires correctly when on the mag only. What happens when you use just the Grid and mag does it fire then if so the problem is the crank trigger is either bad or you are not spinning the motor fast enough on the starter for the crank trigger to work. Use a multi-meter and read the resistance across the two pins on the crank trigger plug. Should read 24 to 40 ohms. What kind of starting system, is it an onboard starter and if so how many volts are you using on the starter 12, 16, or 24?
     
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  3. Adam2833

    Adam2833 New Member

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    Thanks Mike,
    It's remote start with 48v and spins about 460rpm at the crank.
    The resistance across the crank trigger pins is 49-50 ohms so perhaps this is a problem?
    Everything is setup to run with the grid. We only unplug the single white from the violet and green on the mag and plug that back into the mag.
    This will fire and run, the grid still records everything including ignition in/out and the rev limit.
    Plug the violet and green back into the white and it wont fire.

    I can post a screenshot tonight of the grid showing the ignition in/out graph. If the crank trigger was faulty this would not graph correctly?
    Thanks
     
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  4. Mike Canter

    Mike Canter Top Dragster
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    So using the Grid built in data acquisition system set it to record start recording at 200 rpm the hook the Grid into the system and try and start it. Then after it will not start look at the Ignition In and Ignition Out and tell me what you see. Are you positive that you have power to the Grid’s orange and red wires?
     
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  5. Adam2833

    Adam2833 New Member

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    Hi Mike,
    There is definitely power to the orange and red wire checked at the main plug going into the grid.
    I set the start rpm at 200 and plugged the mag into the white wire for the grid.
    The ignition in / out appear to be ok.
    It was 9.30 at night here so I had the leads off so it wouldn't fire anyway.
    I need to double check the crank trigger against the magnet but the pulley is large and needs to come off the check that properly.
    How much timing is too much to fire?
    Thanks
     

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  6. Mike Canter

    Mike Canter Top Dragster
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    According to the Ignition In/Out attachment the crank trigger And Grid are working just fine. Make sure a pin in the plug on the white wire hasn’t pushed back inside.
     
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  7. Adam2833

    Adam2833 New Member

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    Thanks for the assistance Mike,
    I'll double check the pin on the white wire.
    It looks as if the grid and pickup are working correctly.
    I'll double check the pickup position and try and start it again on the weekend
    Thanks
     
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  8. Mike Canter

    Mike Canter Top Dragster
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    The other critical item when using a crank trigger is rotor phasing. If it is out by too many degrees the motor will not start.
     
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  9. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
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    I agree with Mike, I have seen this happen many times, if the mag phasing (mag timing) is too far off of the trigger/grid timing, it will not fire on the grid. I always recommend to have a cross over switch that will definitely help troubleshoot these type issues and makes it easier when checking timing in a warm up to be able to switch back and forth without having to kill the car.

    So lets say your target timing is 25. Since it will run on the mag, make sure the mag is at 25.

    Now here's a part you may be missing. I don't have a degree wheel in front of me, but magnets on the degree wheel will be 20 degrees off of the big 90 degree marks on the wheel. I want to say it's 20 degrees back, but I'm not certain. You may have to remove the pulley to see the side where the magnets are epoxied in. I usually put a mark on the degree wheel to show the magnets.

    Ok, once you have the magnets located, you need to have about 3 degrees lead built in to compensate for the grid processor delay. I usually remove the 'eyeball' so I can see the pointer on the slider good. So if 25 is the target, put the degree wheel at 28 on the timing marker, then line the trigger slider up with the magnet. That should get you real close.

    If you do all that and it still doesn't fire, one more thing to try is to use the mag trigger as the trigger for the grid and hook the wire that normally goes to the trigger to the mag trigger. If it fires that way but not on the trigger, you either have a dead trigger or not enough cranking speed.

    I also run about .075 trigger gap. You can take one of the small zip ties and double it over and it will be roughly .075.

    To answer your original question on programming, the Grid is working off the number you tell it. Every number in the Grid is based off the Maximum timing reference in the grid. So when you put a zero file in the grid with no retards, if the timing light shows 25, that's what you need to put as Maximum timing reference. Now if you are going to try to use the "main timing" option and you tell it 24, that means it's going to retard one degree.

    If you are not real proficient on the Grid yet, I would just stick to the Launch curve only and maybe use a shift retard if you think your car needs one. With the blue wire not hooked up, it's going to cycle through as soon as power is turned on, then not cycle through again.

    The new MSD Grid tester is pretty slick and easy to use and a great diagnostic tool.
     
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  10. Adam2833

    Adam2833 New Member

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    Thanks for the replies Mike and Will.
    We attempted to fire the car this past weekend but had an issue with the Anderson connector on the starter and was unable to start for this reason. We'll get it fixed this week and try again.

    When we initially fired the car mid last year it ran through the grid, it's only been since the belt shredded that it hasn't.
    The crank trigger looks like it had been hit and was advanced and one of the nuts was damaged and showing it was tight before it actually was. This advance probably meant the rotor phasing was then out by enough.

    Thanks
     
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