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MSD 6AL started making rat-a-tap-tap sound all of the sudden - any ideas why?

Started by XH29N0G, August 16, 2013, 09:29:36 PM

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XH29N0G

I just brought my car back from restoration a few weeks ago.  I drove it 4 hours back, and then again for about a 1/2 hour.  It has an MSD 6AL box with rev limiter that I set.  It has an electronic distributor from Muscle motors.

Tonight when I started it up, it started up fine, then after about 30 seconds, a loud tapping noise maybe 5-10 hz.  I turned off the engine and the noise stopped.  Now as soon as I turn the key, the tapping/clicking noise starts.  It sounds like a loud spark discharging.  Does anyone have any ideas on what I should do? 

I looked online and did not see anything.  I also am new to this ignition so I do not know its ins and outs well.

Thanks for any help or suggestions.
Who in their right mind would say

"The science should not stand in the way of this."? 

Science is just observation and hypothesis.  Policy stands in the way.........

Or maybe it protects us. 

I suppose it depends on the specific case.....

A383Wing

are you sure it's the box and not a plug wire shorting out somewhere?

XH29N0G

Short answer: No.  Long answer is pretty sure.  My uncertainty is because I turned the key and had 3 friends plus my son locate the sound.  They pointed to the box.  If I had done it, which I will do tomorrow morning, I could confirm that they did not trick themselves. 

It also happens before the engine fires.  Does the MSD send a signal as soon as the key makes the ignition live?

Thanks for the response.
I certainly hope it is a plug wire - that would be simple.  They are new firecore wires. 
Who in their right mind would say

"The science should not stand in the way of this."? 

Science is just observation and hypothesis.  Policy stands in the way.........

Or maybe it protects us. 

I suppose it depends on the specific case.....

A383Wing

Mine is quiet when key is on...also when engine is running...maybe a bad ground connection?

XH29N0G

Thanks.  I will check connections to see if this is the cause.  It is quite a loud snapping sound - louder than the engine.
Who in their right mind would say

"The science should not stand in the way of this."? 

Science is just observation and hypothesis.  Policy stands in the way.........

Or maybe it protects us. 

I suppose it depends on the specific case.....

XH29N0G

Problem solved.  Should have checked myself... :slap:.3 friends and my 15 year old son were wrong about where the sound was coming from.  It was the motor on the headlight doors  :brickwall: :brickwall: :brickwall:  Now, I will look at solving that.  If anyone knows what makes headlight door motors on 1970 chargers make a loud rat-a-tap-tap I would love to hear, but I think I can take it from here.
Who in their right mind would say

"The science should not stand in the way of this."? 

Science is just observation and hypothesis.  Policy stands in the way.........

Or maybe it protects us. 

I suppose it depends on the specific case.....

Dodge Don