5.9 magnum fuel sync?? - DodgeForum.com



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5.9 magnum fuel sync??

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Old 03-18-2014, 02:03 PM
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44dakota 44dakota is offline
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Default 5.9 magnum fuel sync??

hi guys,ive just completed some work on my magnum engine.it started with a worn lobe on my camshaft,so i ended up replacing the cam bearings,put a new crane 2020 camshaft with new lifters and a comp cams double roller timing chain..
everything actually went well on this swap,i marked the distributer when i pulled it out so i could get it back in exactly the same,the engine fired up and idled smooth and sounded very nice,but,i noticed if i give it a hard snap from idle only! it would give me a quick backfire out the throttle body,but,if i do it anywere else in the rpm range it would be fine..
so with all the talk about needing a 4000$ scan tool to set fuel sync.i lossend the distributer and started the engine,i gave it a quick throttle snap and got a short and quick pop,so i turned it just very slightly clockwise(maybe 1/8 to 1/4 inch in movement)which would be simular to retarding the timing and bingo!! no backfire!!!
so my question for you guys,would you call this good enough or should i still bring it to a dealer to get it set???i really dont want to do that though.lol..
i havent actually driven it down the road yet,i guess that will be the real test...
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Old 03-18-2014, 10:33 PM
magnethead magnethead is offline
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the sync, in as laymens as I can reasonably get it (because even I don't fully understand it), is accepted by the computer as long as it is within 6 degrees of nominal. As i recall, going to -3 degrees yields fuel mileage and +3 degrees yields more power.....supposedly. By turning the distributor, not only are you changing the rotor phase and timing, you are also adjusting when the injectors fire relative to the intake valve's position. Again, that's all I know...it's way over my head.
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Old 03-18-2014, 11:12 PM
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00DakDan 00DakDan is offline
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It's just my opinion but with the time and money you've invested, get the fuel sync checked. It shouldn't be that expensive if you can find a shop to do it. It's quick to check. Snap-On makes scanners that will do it that a good shop should have.

If you do decide to just tweak it yourself, make very small changes at a time.
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Old 03-19-2014, 12:49 AM
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44dakota 44dakota is offline
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thanks guys,yea this fuel sync thing is just weird to me,im definatly old school..once i get to drive it down the road ill determine if i want to take it and get it checked,right now my y pipe is rubbing my front driveshaft(better fix that!) after putting a set of shorty headers on it,it must have changed the position of the pipe,im really starting to get used to working on this truck..lol..
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Old 03-19-2014, 09:50 AM
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It's really as important as setting the spark timing. When it's right you'll get the best power and mileage.
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