Another Grid timing question

Discussion in 'Manton Push Rods Top Alcohol Tech Questions' started by Big Steve, Mar 11, 2019.

  1. Big Steve

    Big Steve Member

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    Blown BBC TD application. Using a small crab distributor cap how much timing do you think can be pulled before I start having cross fire or other issues due to rotor phase. Went 3.87 this weekend, base timing at 28*, pulling 6* with 4* back in by 1 sec. that 87 equates to about a 5.94 or so. Need to find a curve that works to slow to the 6.10 index for Houston in 2 weeks
     
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  2. Critical Mass

    Critical Mass Member

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    Big Steve,
    You could try taking out a 0.1 at a time from 4.0 deg. until you get to your 6.10 index.
     
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  3. Mike Canter

    Mike Canter Top Dragster
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    Well, 360* divided by 8 is 45*. So you have 45* between posts so if you divide that by 2 then the middle crossover Point is 22.5* max theoretical degrees before you have cross fire but you never want to push it that much. If you have a fouled plug or a bad plug wire that the spark has a hard time going down then it will find another path. If all is in great shape then I would say you are safe pulling out up to 8-9* with no problem. Your plugs need to be gapped at .015-.016” to make it easy for the spark to jump when the cylinder has high pressure and lots of alcohol in it. You didn’t say if you were using a crank trigger or not.
     
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  4. Bjs344

    Bjs344 Member

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    Typically I’m phased around 24, base timing at 28-31. I’ve gone down as low as 13 or maybe 12 degrees for a couple ticks (11-12 degrees out of phase). Had a friend that went 14 out of phase and claimed that’s when it started cross firing. These were crab cap crank trigger distributors.
     
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  5. Mike Canter

    Mike Canter Top Dragster
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    Yes with a crank trigger and moving the rotor phasing like you have done you have added safet and can safely add another 4*. Wouldn’t go any further than that.
     
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  6. Big Steve

    Big Steve Member

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    My big concern was with the crab cap because it is so small. Yea I have a crank trigger. I know someone who knock 15* out this past weekend but only for .400 and brought it all back in by 2 secs but he has a large cap. It was a procharger car and I would of thought it would cross fire but didnt and made a good pass
     
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  7. caseyspradlin

    caseyspradlin Member

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    i have successfully pulled 12 with this distributor set up
     
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  8. Krister johansson

    Krister johansson New Member

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    45? It is 90 "crank" degrees between cap terminal.
    My tow cent from Sweden...
     
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