Resistive Ignition Lead Repair
From
G8MNY@4:902/6 to
WW on Sat Dec 7 09:00:26 2024
By G8MNY (Updated Dec 22)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
These carbon particle leads are standard on petrol engines with or without distributors/coil packs, but not found on small magneto ignition engines like lawnmowers and generators! The advantage is much reduced QRM, but reduced spark plug power and unfortunately a short lifetime, 10 years? But do check for bad plugs, as they can fail intermittently too usually when hot.
black outer rubber
ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿
³ white inner rubber ³
Carbon dust coated string :::::::::::::::::::::::::::::::::::
Gives about 1k per inch ³ white inner rubber ³
ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ
black outer rubber
Lead breakdown is caused due to the current passing through the carbon particles on a string, heating and oxygen near the exposed surfaces will over time generating CO2 making the particles smaller and causing bigger gaps between them and then more sparking and heating etc. Normally the hot Spark Plug ends are where the failures are, a bit of examination at night looking for spark light and hearing clicks, or a meter will locate the cause an occasional missing engine fault. Replacing the lead with new will cure the problem for few years, but here is a ZERO COST DIY repair...
REPAIR
If spark light is seen at an end (not from on outer to nearby earth) or the lead is higher resistance than expected, it is usually the hot plug ends that fail. An internal wire (paperclip) can be inserted along the string once the spark plug termination clamping the end is removed. This hardest bit is actually carefully breaking the rubber glue with a small sharp long screwdriver inserted along the cable outer to free up the plug shield boot.
Boot
========_____
Spark Plug ()²²²ÜÜÜÜÜÜÜÜÜÜÜÜÜÜlead
========~~~~~
Then slide the boot up the lead, carefully bend the metal contact tangs out of the lead (so they can be reused) abd free the lead. Straighten a paper clip to leave 1 U fold, and push long piece down centre of lead until U fold is home. Measure the resistance, it should be a stable resistance now & possibly lower. Reassemble the metal contact griping the paper clip U & crimp it down on the lead again. slide boot back & re-glue once all leads retested.
Also see Tech Bul on "Towing & Reversing Bleeper", "Towing Socket for Caravans" "Vehicle Gutter /P Mast Support" & "Wheel Nuts".
Why Don't U send an interesting bul?
73 De John, G8MNY @ GB7CIP
-----------------------------------------
ARGEN-X BBS - IPV6 TELNET LU9DCE.DYNU.COM -----------------------------------------
--- Mystic BBS v1.12 A48 (Linux/64)
* Origin: ARGEN-X BBS (4:902/6)
From
G8MNY@4:902/6 to
WW on Wed Dec 11 05:59:32 2024
To : TECH@WW
By G8MNY (Updated Dec 22)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
These carbon particle leads are standard on petrol engines with or without distributors/coil packs, but not found on small magneto ignition engines like lawnmowers and generators! The advantage is much reduced QRM, but reduced spark plug power and unfortunately a short lifetime, 10 years? But do check for bad plugs, as they can fail intermittently too usually when hot.
black outer rubber
ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿
³ white inner rubber ³
Carbon dust coated string :::::::::::::::::::::::::::::::::::
Gives about 1k per inch ³ white inner rubber ³
ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ
black outer rubber
Lead breakdown is caused due to the current passing through the carbon particles on a string, heating and oxygen near the exposed surfaces will over time generating CO2 making the particles smaller and causing bigger gaps between them and then more sparking and heating etc. Normally the hot Spark Plug ends are where the failures are, a bit of examination at night looking for spark light and hearing clicks, or a meter will locate the cause an occasional missing engine fault. Replacing the lead with new will cure the problem for few years, but here is a ZERO COST DIY repair...
REPAIR
If spark light is seen at an end (not from on outer to nearby earth) or the lead is higher resistance than expected, it is usually the hot plug ends that fail. An internal wire (paperclip) can be inserted along the string once the spark plug termination clamping the end is removed. This hardest bit is actually carefully breaking the rubber glue with a small sharp long screwdriver inserted along the cable outer to free up the plug shield boot.
Boot
========_____
Spark Plug ()²²²ÜÜÜÜÜÜÜÜÜÜÜÜÜÜlead
========~~~~~
Then slide the boot up the lead, carefully bend the metal contact tangs out of the lead (so they can be reused) abd free the lead. Straighten a paper clip to leave 1 U fold, and push long piece down centre of lead until U fold is home. Measure the resistance, it should be a stable resistance now & possibly lower. Reassemble the metal contact griping the paper clip U & crimp it down on the lead again. slide boot back & re-glue once all leads retested.
Also see Tech Bul on "Towing & Reversing Bleeper", "Towing Socket for Caravans" "Vehicle Gutter /P Mast Support" & "Wheel Nuts".
Why Don't U send an interesting bul?
73 De John, G8MNY @ GB7CIP
-----------------------------------------
ARGEN-X BBS - IPV6 TELNET LU9DCE.DYNU.COM -----------------------------------------
--- Mystic BBS v1.12 A48 (Linux/64)
* Origin: ARGEN-X BBS (4:902/6)