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Thread: Backfire/No Start/Analog 6AL

  1. #1
    Join Date
    Sep 2017

    Default Backfire/No Start/Analog 6AL

    Have a 557 Ford with a Analog 6AL box/Blaster 2 Coil/MSD8580.

    Ran truck all season (same setup for years in fact), no issues, no changes, didn't mess with anything. Went to last pull of season, started, pulled off trailer, idled through pits, lineup and to line, hooked up and off we went and about 20' it sputtered and died. Backfired bad when trying to restart. Got in pits, thought maybe dist slipped-it was tight, checked, cap, rotor, pickup, mech adv-all intact. Rotated motor with breaker bar, no knocking then or anything hitting (was kinda knocking when trying to start). Checked fuel, bowls full, carb squirting, butterflies intact. When trying to start, best way I can describe is it sounds like 5 cylinders are hitting right on, but 3 are WAY OFF. Tried retarding the dist, no change, retard more, no change.

    Got truck home, pulled dist, inspected, coil, wiring, reluctor, pickup, mech advance, gear, cam gear, oil pump drive-all good. Ohm tested pickup, got around 450 ohms, rotating slowing by hand it will dip down to 300, not sure what to think of that. Usually these pickups just "don't fire" when they go bad. Drove pin out of cam gear, it was intact, reinstalled. Re-installed dist where it was. Pulled sparkplugs-intact. Removed valve cover, rolled motor over, inspected all rockers (solid roller cam) by hand, all had decent clearance by feel (for what I am/was after here) and all moving (cam not broke). Rolled over to TDC ign, rotor right on #1 and rockers agree, so engine in mech and ign time. Boroscoped all cylinders while rolling over, no damage, no valve clipping, all pistons moving so no broken rods/crank.

    Put everything back together, found #7 plug wire got burned, replaced it with spare thinking it coulda been back feeding spark/grounding out to different cyls, tried to start, no change, fooled with ign timing by hand/guessing retarding/advancing, not much change. Checked power and grounds to box, cleaned them-no change/same exact issue.

    Did not bother spark testing box or coil as I have spark, just at what seems the wrong time on some cylinders. My thoughts are it's like the coil is being told by the box or the pickup telling the box to discharge at the wrong time on some cylinders and it's jumping the spark ahead or behind (whatever is closest) in the cap. I have had a bad ignition module do something similar to this in an HEI style dist, wouldn't run below 3000rpm, I am not trying that with this high dollar motor at 14.5:1 compression, as it's gonna wreck something, not to mention it was above 5500 rpms when it initially died.


  2. #2
    Join Date
    Jan 2010
    Brisbane, Australia


    Can you give some photos of the inside of the cap and BOTH SIDES of the rotor please?


  3. #3
    Join Date
    Sep 2017


    Attachment 4494Attachment 4495Attachment 4496

    Not sure what you meant by both sides of rotor, but here is top and bottom, in any matter I examined both closely already and again tonight, could find nothing wrong, no carbon tracking, no cracks... the contact look like they were used all summer (this dist was new this spring due to the old ones mech adv flying apart). I also keep a new/spare cap, installed it, no change. Also took a rotor out of another distributor (was working fine) and tried it, no change.


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