Checking and installing a pick up coil
Thread Starter
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Joined: Sep 2007
Posts: 55
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From: Buffalo NY
Checking and installing a pick up coil
Well I guess its about time to change both coils, Ignition and pick up, after all they are 31 yrs old. My car.... 79 L82, breaks up under a load or hard acceleration and the tach goes crazy. I think its my pick up coil. My question is how can I check to be sure its the pick up coil and how difficult is the job? It looks like I gotta take the distributor out to replace the pick up coil. hmmm I'm looking for any advice or assistance.
Thanks,
Carl
Ps, Pretty sure its not a fuel problem. The tach drops real fast and immediately bounces back. The car doesn't bog down like its fuel starved it breaks up like some one is throwing a switch off and on.
Is there anything else I should replace while I have it apart...besides rotor and cap and wires.
Thanks again
Thanks,
Carl
Ps, Pretty sure its not a fuel problem. The tach drops real fast and immediately bounces back. The car doesn't bog down like its fuel starved it breaks up like some one is throwing a switch off and on.
Is there anything else I should replace while I have it apart...besides rotor and cap and wires.
Thanks again
Racer
Joined: Mar 2006
Posts: 264
Likes: 1
From: west central INDIANA
Hey Carl,
As you know your pick-up coil wires are constantly being flexed and bent, during vacume advance operation. GM recomends testing them in this way with an ohm meter and a vacume pump actuating the advance unit. check resistance( I think 1500 ohms) during full range of advance movement. you should see a needle movement if you have a broken wire. Sometimes you can simply unhook you vacume line, the drive it. If you find it is the pick up coil, then you will need to pull the Dist. Knock out the rool pin in drive gear, to replace this part. Hope this helps.
As you know your pick-up coil wires are constantly being flexed and bent, during vacume advance operation. GM recomends testing them in this way with an ohm meter and a vacume pump actuating the advance unit. check resistance( I think 1500 ohms) during full range of advance movement. you should see a needle movement if you have a broken wire. Sometimes you can simply unhook you vacume line, the drive it. If you find it is the pick up coil, then you will need to pull the Dist. Knock out the rool pin in drive gear, to replace this part. Hope this helps.
Last edited by 1980 blue L48; Apr 7, 2010 at 12:37 PM.
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
I find that I will not use a pickup coil where the form plastic has turned dark tan/brown....time to retire that coil...the outer wrapping is falling off or will be shortly.....
what need do it tap the shaft outta there, and hope not so much junk on the shaft it takes the upper bushing with it....if it does, i'ts not end of the world, just a PIA to get in there again....there is a really tiney snap ring on top of it that secures the coil in place....
check end shaft clearance, 20 mills is fine...not too much more....but no less the 5-10 in play there....
IMO, the spark coil on top...solder the wires where they are crimped on to the crazy bent connectors, they used to crimp right through formvar enamel on the wire, and so I caught one doing same thing, only engine would quite near 3000 rpm....soldered the wires, and so good to go forever....
make sure the large coil body is grounded the way it should be, don't leave out any wire/clip to allow it to be ungrounded.....it causes more stuff to happen.....don't ask, please....
what need do it tap the shaft outta there, and hope not so much junk on the shaft it takes the upper bushing with it....if it does, i'ts not end of the world, just a PIA to get in there again....there is a really tiney snap ring on top of it that secures the coil in place....
check end shaft clearance, 20 mills is fine...not too much more....but no less the 5-10 in play there....
IMO, the spark coil on top...solder the wires where they are crimped on to the crazy bent connectors, they used to crimp right through formvar enamel on the wire, and so I caught one doing same thing, only engine would quite near 3000 rpm....soldered the wires, and so good to go forever....
make sure the large coil body is grounded the way it should be, don't leave out any wire/clip to allow it to be ungrounded.....it causes more stuff to happen.....don't ask, please....
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
The fuel system can have the same symptoms. If your float is set too low, hangs up, or the needle valve is restricted you can get the same symptoms when you need a higher fuel flow. Also, if the fuel filter is almost plugged up, you won't get the flow capacity you need when you press on the accelerator. When the engine gets no fuel, it acts exactly like it has no spark or no air. If there is nothing to fire with the spark, it might as well have no spark.
Race Director
Joined: Apr 1999
Posts: 11,520
Likes: 13
From: CORVETTE 77 385 C.I. TEXAS
The pickup coil system is considered to be very reliable & many say the pickup coils do not fail. The movement of the vac. advance can cause the leads to break internally- may not be noticeable looking at them. Move the vac. advance while checking.
I bought a "new in the box" HEI, checked it out before install & found the pickup coil "bad". I disassembled including the pickup coil & found a lead was not soldered to a pickup coil wire. Soldered to fix.
Replace ig. module also.
I bought a "new in the box" HEI, checked it out before install & found the pickup coil "bad". I disassembled including the pickup coil & found a lead was not soldered to a pickup coil wire. Soldered to fix.
Replace ig. module also.
Melting Slicks
Joined: Oct 2002
Posts: 2,865
Likes: 1
From: I may be getting old but I refuse to grow up
The pickup coil system is considered to be very reliable & many say the pickup coils do not fail. The movement of the vac. advance can cause the leads to break internally- may not be noticeable looking at them. Move the vac. advance while checking.
I bought a "new in the box" HEI, checked it out before install & found the pickup coil "bad". I disassembled including the pickup coil & found a lead was not soldered to a pickup coil wire. Soldered to fix.
Replace ig. module also.
I bought a "new in the box" HEI, checked it out before install & found the pickup coil "bad". I disassembled including the pickup coil & found a lead was not soldered to a pickup coil wire. Soldered to fix.
Replace ig. module also.
I had these wires break on a 79 Pontiac I had
Thread Starter
Advanced
Joined: Sep 2007
Posts: 55
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From: Buffalo NY
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
The pickup coil system is considered to be very reliable & many say the pickup coils do not fail. The movement of the vac. advance can cause the leads to break internally- may not be noticeable looking at them. Move the vac. advance while checking.
I bought a "new in the box" HEI, checked it out before install & found the pickup coil "bad". I disassembled including the pickup coil & found a lead was not soldered to a pickup coil wire. Soldered to fix.
Replace ig. module also.
I bought a "new in the box" HEI, checked it out before install & found the pickup coil "bad". I disassembled including the pickup coil & found a lead was not soldered to a pickup coil wire. Soldered to fix.
Replace ig. module also.
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From: Buffalo NY
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