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Ignition problems

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953 views 6 replies 4 participants last post by  nastynate  
N
#1 ·
My engines breaks up really bad when I go to the floor. It's a 496/afr 305's... 10-1 comp, single plain hurrican intake , 850 mighty demon with 80-84 for jets. Timing is 18 initial with 18 advance. From the start engine ran fine . Then i started having ignition problems on start up. I traced that to the harness that plugs into the distributor coming from msd 7al-2 box. Problem was solved when I bent prongs to make better connection.Engine started and would idle but under any kind of accelaration it breaks up really bad like all the wires are cross and when you go back to idle it acts normal. I have a feeling thats it's ignition but but I can't seem to find it.I've jetted the carb down to the afformention jet sizes thinking that was it. I've ran the engine at night and don't see any arking anywhere. It has a 140 amp alternator and a fresh battery. ground strap from engine block to frame and from engine to battery. Help me enjoy this engine someone pleaseeeeee......:(:(:(Reply here or at bignatechevy@yahoo.com
 
B
#2 ·
It might be the ignition box, but gotta begin with the simple and cheap stuff first....what about the cap and rotor? Maybe a crack in the cap, or very badly corroded contacts inside perhaps? If and when that's ruled out, then what about a clogged fuel filter? Are there a lot of miles on it? Do you have one of those inline stone filters? Those type are very fine and can be restrictive too. particularly if you're getting any setiment from the tank coming in at all. I'd have to wonder about the coil. You can disconnect the coil wire from the coil and hold it close enough to the coil while someone turns the engine over (if you don't have a remote trigger to do it by yourself from outside of the car) and see if the coil spark is steady or intermittent. Not sure if that would be the best way to diagnose a bad coil, but that is one way.
 
K
#4 ·
How old are plugs? What is their gap? Clean cap and rotor with trichlor, and only handle ignition parts with nitrile gloves to keep them free of finger prints. Check voltage going to CD box. Are all ground connections coming off the engine, as opposed to coming from the body to the engine? Do all ground connections have star washers? Is the CD box well grounded? If necessary, run two wires. Are you getting 13.5+ volts to the CD box at idle?

If you have ONE bad plug with a 360 manifold, it will make the engine run badly. How about a leaking intake valve, and all the stuff that Billy said?
 
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