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Unread 05-23-2010   #1 (permalink)
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Default 1989 5.0 engine timing advance

Hi everbody I have an 89 5.0 H.0 motor in a 76 bronco i was wondering about what the timing should advance to when the engine is reved up also have a problem with it back firing in the intake and wondering if I should use 12 or 14 deg instead of 10? would this cure my backfire
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Unread 05-23-2010   #2 (permalink)
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12-14 will work may require higher octane gas. May fix back fire but i doubt it. Got a vaccum leak? Spary the intake with tb cleaner see if the rpm's rise
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Unread 05-23-2010   #3 (permalink)
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Not sure if i have a vaccum leak or not, I will check forsure, Everybody that i talk to seems to think the timing is off somewhere
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Unread 05-23-2010   #4 (permalink)
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Well your air to fuel is off but from what is the question. Need to know everything about your motor. Are you running mass air is the conversion right, what maf if so and do the injectors match. Are you setting the timing correctly by pulling the spout conn. Is your fuel pressure at 38# at idle with vacuum line off. ETC. What mods if any...
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Unread 05-23-2010   #5 (permalink)
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most likely it is vacuum leak, but having timing set to low can also cause is. if it is back firing when idling its a vacuum leak but if it is back firing when on the throttle like cruising at a steady pace then it is timing.
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Unread 05-24-2010   #6 (permalink)
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The motor does not backfire at an idle it only does it when pressing on the throttle under load. Not sure how many pounds are flowing through the injectors at an idle will find out what it is and also what maf I have. It came out of a 88 lincoln car so i think it was a speed density motor to start with but i sent my comp off to be checked out with the new wiring harnes that i had to buy
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Unread 05-24-2010   #7 (permalink)
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I checked for a vaccum leak and I dont have one i did advance the timing to 12 and it backfires less than it did before so i tink im going to try 14 deg now and see what that does. Also how do you measure your maf? is it the inside diameter where the sensor is plugged in?
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Unread 05-26-2010   #8 (permalink)
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you might have a weak ignition or a bad valve seat, or something, but try replacing the spark plugs or checking them, the wires, and make sure everything is all connected right and in the correct order.
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Unread 05-26-2010   #9 (permalink)
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i got my heads rebuilt and everything is new except my rocker arms. Do you think that i could have a bad spark plug even on a new ones? I might try to start over with my timing from the timing gears.
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Unread 05-27-2010   #10 (permalink)
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could be a bad plug, but check your timing and when you check it rev up the motor and see if it advances or not.
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Unread 05-28-2010   #11 (permalink)
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shoot, could simply be bad gas! Check all the plugs for temperature after its been running a few minutes (if one's colder than the others its not firing). Then pull the plugs n look em over if you've verified it's not just crappy gas.
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Unread 05-28-2010   #12 (permalink)
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i pulled the plugs and all of them are white except #1 and #3 which have the new injectors the two plugs are black on the ceramic and white on the electrode so i swapped 1 and 5 injector to see if it follows or if it is in the wiring
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