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Old 07-06-2013, 05:09 PM
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Rich88 Rich88 is offline
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TFI coil buzz?

So I'm getting ready to install a relay to feed my recently installed TFI coil with system voltage instead of the 8.8V it currently gets thru the stock resistive wire. First thing I did was (while engine idling) was to test-jumper from battery (+) terminal right to the coil (+) just for the heck of it.

I instantly got an unexpected loud buzzing from the coil and thought maybe something was about to fry. After carefully tapping the coil (+) with the jumper a few times I realized it was really "transformer buzz" and being caused by the fact that the coil body is not really tight in the steel shell surrounding it, and its simply electromagnetic energy causing the coil to beat against it, and the act of providing it with higher voltage just made it work harder...providing the increased sparkage it should.

But it really IS a noticeable nuisance buzz, and worse than one tolerates with an e-pump. After staring at it for a while it occurred to me that maybe I could put the coil on the bench and drizzle epoxy into the crack-spaces between the coil and shell to get rid of the play.

Anyway, is this buzz typical? Did I get a lousy coil? Thoughts?
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Jeepasaurus (Wagonus Grandi quadropedus)
88 GW 360-.030 over/2150/727/229/Posi, e-pump, AC (broke), tow package, Monroe Air Shocks, TFI, CTO-Free, AIR-free, oil & tranny coolers, dried knuckle blood all over, GM 350 TBI in a box, waiting...
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Old 07-06-2013, 06:38 PM
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serehill serehill is offline
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Interesting

Never heard of that but the theory sounds logical. I would think the coil has some flaw in the casing.
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80 Cherokee
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Edlebrock performer intake
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Old 07-06-2013, 11:34 PM
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New coil? Take it back. Used coil? Get another one.
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Old 07-07-2013, 05:47 AM
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Quote:
Originally Posted by serehill
Never heard of that but the theory sounds logical. I would think the coil has some flaw in the casing.

What the heck, I'll try the epoxy thing.
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Jeepasaurus (Wagonus Grandi quadropedus)
88 GW 360-.030 over/2150/727/229/Posi, e-pump, AC (broke), tow package, Monroe Air Shocks, TFI, CTO-Free, AIR-free, oil & tranny coolers, dried knuckle blood all over, GM 350 TBI in a box, waiting...
"You're an FSJ'r when the parts guys memorize your name, phone & credit card#."
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Old 07-07-2013, 10:19 AM
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serehill serehill is offline
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yeah

I went that way the first time. My coil is epoxy. No oil coils for me. The blaster 3 is what I'm running.

So I'm just curious. You connected the 12 volt wire while the 8.8 volts was still connected to it?


I guess anything is possible I would assume the vibration would be from a loosely wound coil getting epoxy to saturate the entire circumference means there's no oil where there should be. You might want to also verify the input voltage of the coil I have no idea if it is correct. It should have been a 13.8 v coil.
I agree if this is from the mounting being loose then tightening the bracket should have fixed it. I would be concerned the coil windings are touching the outside casing. If that is the case it has a manufacturing flaw & when the insulation wears off the coil then Bye Bye Coil.
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80 Cherokee
360 ci 727 with
Comp cams 270 h
NP208
Edlebrock performer intake
Holley 4180
Msd total multi spark.
4" rusty's springs
Member, FSJ Prissy Restoration Association

If you can't make it better why waste your time. No use repeating the orignal mistakes. I'm to old to push it that's why.
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  #6  
Old 07-07-2013, 02:26 PM
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Quote:
Originally Posted by serehill
I went that way the first time. My coil is epoxy. No oil coils for me. The blaster 3 is what I'm running.

So I'm just curious. You connected the 12 volt wire while the 8.8 volts was still connected to it?

I used the one for the 80-something Ford F350 460.

Yeah, it was idling with stock 8.8V feeding it. I just tapped the coil (+) with battery to kick it up momentarily. Also, I jammed some small wood shims in the space between the coil and the frame. No change. Apparently the buzzing IS internal. So I'll drive it down to Advanced Auto to have them listen to justify getting another.

I just completed the re-config for system voltage. See separate post.
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88 GW 360-.030 over/2150/727/229/Posi, e-pump, AC (broke), tow package, Monroe Air Shocks, TFI, CTO-Free, AIR-free, oil & tranny coolers, dried knuckle blood all over, GM 350 TBI in a box, waiting...
"You're an FSJ'r when the parts guys memorize your name, phone & credit card#."

Last edited by Rich88 : 07-07-2013 at 02:36 PM.
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