Misfire, can't find problem and have tried everything. Please Help

Discussion in 'Technical' started by bburns1000, Apr 11, 2014.

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  1. bburns1000

    bburns1000 Member

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    No, Installed cam per manufacturer instuctions. Piston#1 @ TDC and timing marks lined up perfectly.
     
    bburns1000, May 21, 2015
    #46
  2. baddad457

    baddad457 Member

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    "Lunati Street/Strip cam" tells us absolutely nothing. (specs would help) And your admission that you over rev'd it and don't baby it tells me you've damaged something internally. Did you pull the cam back out to inspect it ? Pull the lifters to inspect them ? Backfiring through the carb could be an indication that there's something amiss with one or more exhaust lobes/valves. If an exhaust valve doesn't open, the pressure gets trapped through a few cycles till it escapes through the open intake valve.
     
    baddad457, May 21, 2015
    #47
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  3. lm14

    lm14 Member

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    Check your MSD wiring. There are purple and green wires that don't always stay purple and green and people mix them up. Check those wired between the box and distributor. If they are reversed it will retard the timing.

    SPark
     
    lm14, May 22, 2015
    #48
  4. bburns1000

    bburns1000 Member

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    I finally figured it out. The diaphragm blew out of the pressure regulator. The electric fuel pump was putting close to 100psi of fuel in the carb. Rebuilt the regulator, bought new carb ( the pressure and backfires ruined the old one) degreed the cam and timed it straight up. Runs better than ever now.
    Thanks to everyone for all help
     
    bburns1000, Jun 10, 2015
    #49
  5. 71gold

    71gold Frank Cooper Supporting Member

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    why is there a pump on there that puts out that much pressure?
     
    71gold, Jun 11, 2015
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  6. bburns1000

    bburns1000 Member

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    Car was not street driven in the past, former drag car.
     
    bburns1000, Jun 11, 2015
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  7. Bryant

    Bryant forgot more than learned

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    I'm surprised it didn't shoot fuel out the bowl vents. I would expect it to be able to shoot fuel at least 20 feet up at that pressure!
     
    Bryant, Jun 11, 2015
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  8. baddad457

    baddad457 Member

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    Even on a drag car, a carb doesn't need that kind of pressure in the fuel pump.
     
    baddad457, Jun 15, 2015
    #53
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