help with persistent spark knock
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Joined: May 2000
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From: conneaut usa
help with persistent spark knock
howdy y'all have ainteresting problem not sure where to go with it I get a spark knock when I run 87 octane in my 82 F-100 302 motor the oinly octane I can run with no spark knock is 93 and being a 1982 seems strange I couldnt run a lower octane I did have a miss with it but I replaced the module box and took care of it it wuld only miss at low rpm while driving Ie 45mph in OD and 25 in 3rd well I put the new box in I have also replaced the plus wires cap rotor vaccum lines where needed pulls a 17 Hg consistent which shows a strong engine I am considering it may have had a different cam in it to cause that just a thought ..
Also on another thing I have the early AOD tranny which it seems to clank into gear when it hits Od after getting warmed up and slips when coming out to go to 3rd unless manualy shifted it does it then but not as bad ecspecially if Im at a slower speed when it is at a slow speed it goes in easy just when I kick it down any thoughts
Godbless
Marc Conley
Morganton Nc
82 F-100
W/302
Also on another thing I have the early AOD tranny which it seems to clank into gear when it hits Od after getting warmed up and slips when coming out to go to 3rd unless manualy shifted it does it then but not as bad ecspecially if Im at a slower speed when it is at a slow speed it goes in easy just when I kick it down any thoughts
Godbless
Marc Conley
Morganton Nc
82 F-100
W/302
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Joined: Jan 2001
Posts: 56,992
Likes: 2,741
From: Virginia
help with persistent spark knock
Verify if your egr valve is working. Push up on the valve diaphram at idle and the truck should run rough and may stall. Then, rev the engine when it is warmed up, and you should see the valve move. If this is ok, I would guess you have carbon buildup in the combustion chambers. I think I heard one time where ford dealers were sandblasting the carbon out through the sparkplug hole with walnut shells. I don't know if they still do this or not.
Thread Starter
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Senior User
Joined: May 2000
Posts: 137
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From: conneaut usa
help with persistent spark knock
Howdy thanks for the reply. I can honestly say my egr is not working it has been disabled and thje rest of my emmsions junk ha been removed before i bought the truck Thankfully it is gone i thought about carbon so we tok a spray botle of water and srayed over the carb lightly and what that does is takes the water into steam and then basicaly steams clean the motor Thanks Again
Godbless
Marc Conley
Morganton Nc
82 F-100
W/302
Godbless
Marc Conley
Morganton Nc
82 F-100
W/302
Moderator
Joined: Jan 2001
Posts: 56,992
Likes: 2,741
From: Virginia
help with persistent spark knock
The egr being off, with the original carb, is going to cause it to ping. The carb is calibrated to run with the egr, and with no egr, it will cause the engine to run lean. You could go with an aftermarket carb designed for no egr, or you could mess with the carb you have now and may be able to help the situation. Larger main jets may help.
