Hello,

I was checking the timing on my 89 vert(124000 miles) because the idle was rough and discovered a potential problem.

My engine mods are

Bonez cone filter intake
RB street header wrapped with heat temp tape
Bonez highflow cat
60mm HKS exhaust
Jacobs ignition box
10mm magnacor wires
Reduced ratio pulleys
New NGK plugs

The timing is set at about 0 ATDC on the leading side but it jumps around a little, it is not steady on the mark at ~750 rpm.

When I checked the trailing side it was 20 ATDC but the timing light was not constant. The light would cut out randomly. checking the rear trailing side I got no pulses at all from the light. I pulled the plug wire out a little from the coil and it arched and the light worked.

I have recently adjusted the TPS and it seems fine.

Is it normal for the timing light to not work on the rear trailing plug wire?

Do I have a bad coil?

Thanks in advance

David

 

Best bet check the factory service manual for the ohms reading spec then take a voltmeter to check the resistance.

 

hey if your concerned about the timing light cutting out it probably because of those magnacore wires. 10 mm wires have a lot of insulation so picking up a clear signal is almost impossible to get if you have any old good wires try those with the timeing light and see what you get.

 

I will check using my 89 FSM thanks.

 

I've never had a problem reading timing through my magnacores...

 

I have not in the past either reading through the magnacors. That is why I believe the coil could be bad. Would this cause a rough idle?

 

I just checked my timing and I too have magnicore R100's to be correct . I say check the coil for sure. I use the test method also to check coils in the junk yard if I need replacements. thats how I found a good set to replace my old coils.