What should my ignition timing be?
The ideal ignition timing for power occurs just before the point where detonation or pinging takes place. Correctly timed ignition will cause peak cylinder pressures to occur around 12 to 15 degrees after TDC.
What happens if ignition timing is too advanced?
Spark plugs need to fire at the right time, which can be achieved by advancing or retarding the timing of the engine. Ignition timing advancing means that the spark plugs are firing earlier in the compression stroke, farther from TDC. The air and fuel mixture in the combustion chamber doesn’t burn right away.
How do HEI distributors work?
The HEI distributor is an inductive-discharge-style ignition, but with the points replaced by a solid-state switching device called an electronic ignition-control module. The module works like an electrical switch, turning power on and off to the ignition coil. This, in turn, causes the coil to generate spark.
How do you adjust the vacuum advance on a HEI distributor?
If spark knock occurs under part throttle, an adjustment to the vacuum advance is necessary. This adjustment is made by inserting the 3/32″ Allen wrench into the vacuum advance canister port and turn it two turns counter-clockwise. Test-drive the car and repeat the adjustments until the spark knock is eliminated.
What happens if timing is too advanced?
What should timing advance be at idle?
Most engines have between 5-20 degrees of ignition advance at idle. This is referred to as initial timing.
What kind of ignition does a jeep 258 have?
The Prestolite ignition was the first electronic ignition used on Jeep 258s and it does not have a great reputation. The Motorcraft ignition used on later 258s has a better reputation, but the computer controlled version seems to limit the top end you can get out of a 258.
Which wire to run on HEI ignition?
The HEI ignition has two wires that get connected to it, one is 12v which should be hot on run. The other wire is for the tachometer. It just doesn’t get much easier than that!
What is the firing order on the 258 ignition module?
The firing order on the 258 is 1-5-3-6-2-4. I used a test light to figure out which wire was the hot on run wire to my Prestolite ignition module. I cut off the old plug and soldered on a wire with a spade connector. This wire just plugs into the HEI. All the other wires that went to the ignition module, I just wrapped up in some electrical tape.
How reliable is the Prestolite HEI ignition?
The big cap HEI unit has a reputation for being very reliable. The Prestolite ignition was the first electronic ignition used on Jeep 258s and it does not have a great reputation.