Breaking Belts

Discussion in 'PSI Superchargers Tech Questions' started by Mac, Sep 21, 2014.

  1. Mac

    Mac Member

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    I've broke 3 belts in 7 passes. 2 on the burnout and one after peddling due to tire shake(was a tree malfunction so I was on converter way too long on that pass). 4 of those 7 passes were perfect though so I wasn't breaking them all in a row.
    Checked tooth engagement and it looks great. Also checked ignition connectors and plug wires. Looking for ideas in what else to look at?

    Blown Alcohol 470" BBC
    Littlefield 14-71,HH,K-8 rotors,Davenport mods
    35% overdrive
    8000rpm max
    65 tooth bottom,48 tooth top
    1600/8mm RCD belt
    Stout belt idler with outside support
    MSD Pro Mag 20, Serviced by Bob Wyman
    MSD Power grid
    Leaving on Grids two step @ 4500 rpm
    No fuel bypass on two step
    125" altered
    2 speed converter drive
     
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  2. Critical Mass

    Critical Mass Member

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    Hi Mac,
    Good info, but you didn't tell us anything about your ignition timing and what your plugs look like? I'll bet your problem is a combination of your timing and a lean condition using the two step.
    Joe
     
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  3. Mac

    Mac Member

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    33 degrees
    Plugs barely showing heat
    I take 5 degrees out of the timing at the starting line all in by .8 of a second
     
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  4. blown1969camaro

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    belts

    just something to think about not saying its your problem..... we broke a belt every 2-4 runs (6-7 times and new belts not old dry ones) ....during normal matenice forund a bad broken crank , new crank put 10-12 on and have not broke belt since
     
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  5. Critical Mass

    Critical Mass Member

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    Mac,
    Do you have a data logger? If so, you should look at your spark curve; that Mag 20 might not be able to do the job. You stated that you have good belt alignment and support; misfires are next common cause for breaking belts. Also you should look at your fuel flow data, if you are fortunate to have a flow meter.
    Sorry I can't be more helpful, Joe
     
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  6. Mike Canter

    Mike Canter Top Dragster
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    The most common reason for breaking belts like that is backfires in the intake manifold banging the rotors. This can be caused by a too lean mixture of fuel, a leaking intake valve or a bad or weak intake valve spring, crossfire in the mag caused by a cracked cap, or crossfire caused by outer insulation breakdown of the plug wires. Or a accidental switch of the firing order.
     
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  7. SoDak

    SoDak Active Member

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    I've heard of guys breaking them because pieces of blower stripping material were breaking off and getting "caught" in the intake valve as they were trying to close, thus hanging them open and igniting the intake manifold air/fuel.

    I think we broke some in the past because we used a relay to kill our mag and I think the relay was momentarily killing the engine.
     
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  8. Mac

    Mac Member

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    No data logger. I would think the 20amp mag would have enough juice? A buddy of mine ran a similar combo with a old Super mag 4. Les Davenport does my fuel system so I'm going to pull the pump and have him confirm flow. I'm also going to put new plug wires on then send the mag and Powergrid in for service.
     
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  9. Mac

    Mac Member

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    That's what I was thinking but shouldn't I blow a burst panel? The engine is coming out for winter service so I will go over everything.
     
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  10. JimW

    JimW Member

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    Mac,

    I had a 2 year old grid and had ign problems.
    Sent the grid back to MSD and it came back with a note saying " no problem found, updated to latest specs" still had the ignition problem.
    Bought a new grid and problem solved.

    Just a FYI.

    Jim
     
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  11. Mac

    Mac Member

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    That's what I'm wondering. I'm going to send my mag and grid to Electromotion for a check up
     
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  12. Joad Donnelly

    Joad Donnelly Member

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    You can bench test parts all day long and it still may not reveal a problematic part, it can be hard to duplicate real world conditions on a bench. I'm not saying your plan is a bad idea but just saying that there have been a lot of parts that "tested good" but still were the problem. So if they do come back as good don't automatically take them off the suspect list.

    Joad Donnelly
     
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  13. Mike Canter

    Mike Canter Top Dragster
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    If it was me I would send the Grid to MSD and the mag to Electrimotion. MSD cxn do a lot better job of testing the Grid. What Software version do you have in the Grid? It should be version 1.7.3 dated June 2014. There have been a lot of changes to the software. If you hook up your laptop to the Grid and connect you can select "About" at the top and check the SW Version
     
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  14. Blownalky

    Blownalky Top Sportsman

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    I have 1.3.2 from 2012 and each time I try to upgrade it shows me nothing and says I have the current version. What am I missing and what do I need to do to upgrade? Where can I find the current file?

    Tom
     
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  15. Mike Canter

    Mike Canter Top Dragster
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    Well that might be the problem. There have been major software updates over the last two years. The problem is nobody wants to update because then their old setup files may not work on the updated software. I have had pretty good success with it converting the old files to the new format using the Grid auto-Convert feature. If not then when you do the update it gives you a new sample file which you can change to be what you want and save it. You need to have the laptop connected to the internet and connected to the Grid then go to "Help" at the top of the page and tell it to "Check for Upgrade". From there it will do it automatically. If the car is in a place that you don't have Internet then take the Grid off the car and take it and the laptop to where you have an Internet connection. When you plug the Grid into the laptop with the USB cable it will power up from the laptop. Also make sure you have the latest version of MSD View because they all work hand in hand.
     
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    Last edited: Sep 26, 2014
  16. Blownalky

    Blownalky Top Sportsman

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    Yeah, done all you have said, several times and it's not working. I'm a computer guy by profession so I should be able to figure this out you would think, LOL. Appreciate the help Mike. I'll call MSD as there may be a bit stuck in my unit.

    As an update, just got off the phone with MSD. Turns out if the serial number of you unit is between 1722 and 2460 it needs to be sent back to them as it won't auto update. They have to "unlock" it to make that feature work.
     
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    Last edited: Sep 26, 2014
  17. Mike Canter

    Mike Canter Top Dragster
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    Thanks, that is good to know. I have not run in to that problem. Guess I started with the Grid after serial number 2460. Hopefully that racers with the Grid are reading this.
     
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  18. Blownalky

    Blownalky Top Sportsman

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    As another update to the Power Grid upgrade issue. It turns out my Grid's S/N was in the 2700's so it fell out of the range for sending it back. After several exchanges with a very helpful tech person at MSD and their engineers, they gave me a View and Review software update package that allowed me to update the Grid. I also run the ARC module and there are no new updates to that from 2012.

    The real bonus with this software package is it has a conversion utility in it. When you open up old files, it makes them compatible with the newer firmware update! You don't need to recreate the file again. You just need to remember to save the new converted file and you are good to go.

    Here is the upgraded software.

    Tom
     
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