83 ford pickup only firing 6 of 8 cylinders?

H

help wanted lol

New member
ok kinda stumped here we have 83 ford pickup but has engine from an 86. Ok recently its only been firing off six cylinders, spark plugs were changed and wirest were changed, but the same two clyinders are not firing. take the wire loose and i see a nice arc on both cylnders but there is no change what soever when they are removed in the engines performance, no bog down at all. compression was tested around the seals and such and it all seemed fine... im stumped, a local mechanic was also stumped as well, cant figure out why its not firing off those other two given that i see a nice arc. any idea as to what this may be?
 
ford had several different firing orders for the same motors, just run across the same deal on a ford f150 what i did is cylinder balance the motor pull all the wires loose but leave on cap start motor and one at a time pull the wires off carefully not to get shocked and see if it changes if it does and is hitting good go to the next till you find all the wires that are hitting good and leave the ones that are not helping and move them around with it running if you only have two posts left switch and basically rewire yourself have done this several times with excellent results then you will have the new firing order,
 
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