ignition timing retards at revs

Discussion in 'PSI Superchargers Tech Questions' started by clarky, Mar 13, 2009.

  1. clarky

    clarky New Member

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    Thanks in advance

    Does anyone have a solution or reason why ignition timing retards from the original seting when the motor is reved up to stage rpm not under load. Our system retards up to 1.5 deg however we dont have data logging on our timing system.

    Hemi with rcd single mag drive
    44amp mag and points box/coil
    leahy cranktrigger pick up
    system wired as per msd instructions

    other than this the igntion system doesnt miss a beat

    Thanks

    Clarky
     
    #1
  2. crashly

    crashly Member

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    how much end float has the cam got ?

    ash
     
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  3. clarky

    clarky New Member

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    set cam up at16th end float, however timing is taken from the crank trigger not via the mag.

    thanks
     
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  4. eli

    eli Banned

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    Only thing that comes to mind is rod bearing, check it on # 6 cyl or any other cyl for that matter and see if it moves.
     
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  5. Ken Sitko

    Ken Sitko Super Comp

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    Cam flloat should be .000, maybe .002 at most. Aluminum block grows when hot anyways, so it will never be any tighter. If this is not the problem, it might be in the mag drive. Our mag drive (made by George Sitko) is rock solid at all rpms.
     
    #5
  6. Randy G.

    Randy G. Top Alcohol

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    If you have a crank trigger it shouldn't matter if the cam is falling out of the front of the motor. It also shouldn't matter if George, Larry, Fred or Joey made the mag drive. It shouldn't move. The crank hub is triggering the ignition not the Mag through the camshaft. The crank hub is providing the signal to the pick-up and the crank hub is where you see the signal with a timing light.

    Back to basics. You have unplugged the connector on the side of the mag and you did plug the crank trigger in to the connector like you are supposed to?

    With the engine running with crank trigger the timing light on your mark should be so steady it should look like the engine is shut off and you are holding a Mag Lite on your timing mark.

    Little things to consider. Pick-up gap to crank hub is correct. The pick up bracket bolts/nuts are tight so the pick-up isn't sliding around. Pick-up is properly grounded. Stick another points box on it if you have access to one. I can't assume you have an RCD crank hub/degree wheel set up, so I have to ask if you are sure the degree wheel isn't moving on the hub?

    RG
     
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    Last edited: Mar 13, 2009
  7. blown375

    blown375 New Member

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    This may sound stupid but.... the degree wheel isnt moving is it? loose hub ? loose degree ring? partially sheared crank key? or a loose crank trigger bracket? If the trigger has a switch and check that you are actually running off the crank trigger?
     
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  8. clarky

    clarky New Member

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    Thanks Randy, my next thing to try was a different points box.

    Crank hub is rcd and like brand new and torqued to 400ft/lb, we strip and rebuild motor after every alcohol round in Western Australia, however will definately treat the motor to new key ways.

    Thanks
     
    #8
  9. Mike Canter

    Mike Canter Top Dragster
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    My question is Clarky.....How do you know it is retarding if you don't have a sensor for recording the timing on the data logger?
     
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  10. clarky

    clarky New Member

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    Hello Mike

    We check the phasing of the mag at the start of each meet, then change over to the crank trigger. The timing/crank trigger is checked before every run at idle and at launch rpm with a snap on timing light. We dont have any timers on the motor, nor do we vary timing timing during a run.

    Thanks
     
    #10
  11. LeWhite

    LeWhite BB/Alt

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    Snap On ! Oh shoot! Try a light with no bells and whistles. NO KNOBS!
     
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  12. clarky

    clarky New Member

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    NO KNOBs or buttons on this one, have tried another local quality light and made no difference

    Clarky
     
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  13. Mike Canter

    Mike Canter Top Dragster
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    Is this a new motor and it has been doing it from the start or is it an motor that you have had for a while and it was good then started doing this? If it sudenly started doing this had you just changed something.(sorry if it sounds like we are at the doctor's office)
     
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  14. clarky

    clarky New Member

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    Mike

    The motor has done this for a while, nothing has been changed component or set up wise. I honestly havent worried about it untill now as we have been developing the fuel and clutch systems, now that these are close I want that 1 deg back to stay in the mag. We have played around with the timing adding increments each meet. At the moment I believe we are running at our maximum safe timing point, tried and extra .6 deg and it wants to knock the little end of the rods around.

    I have spoken with some other expereinced racers over here who see the same problem at stage with there timing, also one commented that the mag advances at certain points of the run(racepack logger). We are kinda under agreance that maybe what we are seeing isnt really happening.

    I have organised a new points box and coil for the next round over here and will systamatically change parts out to see if a difference is made.
     
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  15. Mike Canter

    Mike Canter Top Dragster
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    As said earlier the timing is set totally by the crank trigger. The points box is supposed to take care of the magneto retard characteristics. I have found the ignition recording on the Racepak sometimes to be in error especially on the V300. It would seem to me if you are seeing it with a timing light then it is really there. Changing the Points Box is a good idea and I would be interested in hearing the results. The only other thing that could cause it would be the relationship between the crank trigger pickup and the wheel. When you just rev that motor up to the stage RPM it is totally unloaded and I would imagine the crankshaft is flopping around a little. If the crank is flopping around then so is the wheel and therefore the timing would also move. Using a clock dial where is the sensor located? If it is at the 9 or 3 o'clock position then mabe a change (if possible) to a 11 or 5 o'clock position and see if it still happens. We use a front crank support and our timing is dead on. It maybe that when your motor is loaded during a run there may not be any timing movement.
     
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  16. clarky

    clarky New Member

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    Mike

    We run a whipple ontop of the motor that takes no load or power to turn. when I service the motor we do see some minimal damage to number 2 main that would sudjest the crank is wandering a little, nothing i am concerned about, i also see some scuffing from the rcd timing tab on the back of the degree wheel. We run the pick up for the rpm pickup for the motec data logger at 5 oclock and the crank trigger pick up at 8 oclock.

    We run the fresh motor up today on the old points box/coil. Will pm you after the weekend with results

    Thanks

    Clarky
     
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  17. Flyboy68

    Flyboy68 Member

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    Maybe he's running a 8973 and not telling us!!! ha ha ...sorry...had to say it.
     
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  18. Mike Canter

    Mike Canter Top Dragster
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    You just pulled the pin on that #$%%$# hand grenade again:eek:
     
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  19. billy438stroker

    billy438stroker New Member

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    I have a INNAVATORS WEST balancer and a MSD crank trigger... My timing retards as I take up the RPM'S ...The higher I take it, the more it retards...I start out slow and take it up higher... I have tried everything' and still haven't found the problem
     
    #19
  20. jay70cuda

    jay70cuda Well-Known Member

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    Have you checked the cam backlash?
     
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