engine question

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milesstarkey

milesstarkey

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i have a 71 fj40 with a 327. i just put headers on it. they came painted black. the first time the engine heated up the paint melted off, except for one cylinder. i've been driving it for a couple weeks now, and that one cylinder still has fresh paint on it, which leads me to believe that it's not firing. what should i do? i don't know much about this stuff. please help.
 
PHAT MAX

PHAT MAX

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check the plug, cap, rotor, wires....if all that is good, the come back and ask again!
 
T
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You can check for firing at each cylinder. Loosen all the plug wires at the cap so they're just resting in place. Start the engine and pull each wire off the cap one at a time. The engine rpm should go down each time, then come back up when you replace the wire. There will be no change in rpm for a cylinder that isn't firing. Requires relatively large cajones, preferably metallic.

I tried this with my HEI. I found pliers with plastic-coated handles and stood on the tire to insulate myself from ground. No problem, right? On about the 3rd wire I got zapped so fiercely my arm shot around like a catapult and those pliers flew 50 feet, like a frozen rope, and pounded a nice dent in the shop wall. Sheesh! I'm pretty sure I made some strange vocal sounds too.

OK, so the next time I straightened paper clips and tucked them into the cap alongside each plug wire. (This is the trick every service manual warns you not to try so you don't damage the cap or wires.) Clip one end of a wire to ground and tape the other end to a foot long piece of plastic. Hold the tool by the plastic handle and ground each wire in turn with the engine idling. Works a charm! This is an age-old trick but I never knew about it until recently.
 
milesstarkey

milesstarkey

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i pulled the plug and the tip is black, the threads are oily. should i get a new plug?
i'm pretty scared to try the last suggestion, i'd rather just take it to a shop and have it checked.
 
milesstarkey

milesstarkey

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replaced the plug. that paint is burning off just like the others. thanks for your advice. except for the guy who wants me to get shocked. that just didn't sound like the way i wanted to spend my afternoon.
 
toddslater

toddslater

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Yep, get a new plug...check the plug wire, cap where the wire contacts, inside the cap at the contact point. Check that the new plug has good strong spark. If the electrical side is all good....and you are still fouling on that one cyl...time to run a compression check. But lets not get ahead of ourselves yet.
 
toddslater

toddslater

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Damn that was quick Miles....anyway keep an eye on it, anew plug may last awhile in a cyl that has mechanical woes...then poof you'll be running on 7 again. Hopefully it was just the plug and you'll not have to revisit.
 
T
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thanks for your advice. except for the guy who wants me to get shocked. that just didn't sound like the way i wanted to spend my afternoon.
What?? I'm shocked that you would say that. If you try it at night you also get to glow in the dark! :G
 
IDave

IDave

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What a wimp. I've been shocked doing this many times and it never hurt me! :p
 
T

tastyweasel

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I have had good results checking for spark by clamping my inductive timing light pickup to suspect plug wires and pulling the trigger. If the light blinks, something is trying to spark. When a plug fouls out, I usually loose the light on that cylinder.
 

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