I have an 80 FI x1/9..I am in the midst of installing new timing belt and tensioner. trying to get tension correct...have not be able to get engine started yet..in trying to figure things out..I decided to test distributor cap with a multimeter.. I'm not getting a reading..I followed utube video in doing the test...so I think I did it right. Is this result sufficient to determine the cap is bad?
Technical distributor cap test
- Thread starter danield
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Technical distributor cap test
Testing a distributor cap using a multimeter strange , would love to see the method.
As long as the carbon contact for the central ht lead is in place and gently springy Don't worry about testing with a ohm meter.
Do make sure it is clean and dry with no cracks.
...I was a little dubious too..but mine tested like the first example in the video. go on youtube and search for" how to test a a distributor cap with a multimeter" I was not allowed to post the url. anyway..thanks for your input.
Scotty1956
New member
Some dizzy caps have a built in resistor at the centre connection - like some HT leads are carbon and some spark plug caps have resistors. So the general idea is it reduces RF generated interference - noise picked up on the radio. Think the carbon centre electrode has a dual function it is lubricating for the rotor arm and it helps reduce RF.
You could try your multimeter on a high ohms range maybe (haven't tested one myself!) around 5k to 20k ohm? Anyone with better knowledge?
You could try your multimeter on a high ohms range maybe (haven't tested one myself!) around 5k to 20k ohm? Anyone with better knowledge?
What are you testing for?
The cap has to pass very high voltages. The typical 9v battery in a multimeter is not going to faze the cap at all.
Some caps have a resistor between the coil connection and the carbon tip inside, but these rarely give trouble. Mostly the resistor is in the rotor arm, and those do give up.
Usual fault with a cap is when the HT current tracks across the internal surface, instead of through the rotor arm. A careful visual inspection is usually sufficient.
Usual quick test is to remove all four plugs, fit them to their leads and turn the engine on the starter. Each plug should spark in order, with a nice fat blue spark. If doing this with any electronic ignition, make sure the plugs keep a good earth connection with the engine.
The cap has to pass very high voltages. The typical 9v battery in a multimeter is not going to faze the cap at all.
Some caps have a resistor between the coil connection and the carbon tip inside, but these rarely give trouble. Mostly the resistor is in the rotor arm, and those do give up.
Usual fault with a cap is when the HT current tracks across the internal surface, instead of through the rotor arm. A careful visual inspection is usually sufficient.
Usual quick test is to remove all four plugs, fit them to their leads and turn the engine on the starter. Each plug should spark in order, with a nice fat blue spark. If doing this with any electronic ignition, make sure the plugs keep a good earth connection with the engine.
