Misfiring / stuttering issue

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Kikowillers

Kikowillers

Well-Known Member
Joined
Aug 12, 2012
Messages
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Location
Eaton, Australia
Hi guys,

I'm having a strange issue since I installed an MSD Blaster 2 coil, new plugs and wires. Sometimes the car will stutter, as if it had lost spark, and I can't pinpoint why.

This is what I have of info for you mopar detectives:

Currently Points distributor, will install a pertronix conversion kit soon.
Coil installed through ballast resistor. On idle ballast reads, 10.5v in, 7.5v out. Under throttle at 3k rpm, ballast out is nearly 12v (???). Ballast problem?
Plugs are set at .0035 as per factory
Plug wires are 8.8mm good quality stuff

Today I noticed this:
Drove the car in town for about 30mins. Stopped by the side of the road, car idled ok for about 2 minutes, then stuttered until it nearly stopped, then regained idle.

A few minutes later, while going through a roundabout at low rpm, it happened again. I increased rpm, problem went away.

It feels like it happens at low rpm, but I can't be completely sure. Maybe a problem with my very old charging system? The alternator only puts out proper charging past 1,500rpm.

I even thought it could be dirty fuel, but I keep thinking if that was the case then it should be happening more often.

How's this for a puzzle wrapped on an enigma?

Cheers fellas!
 
Swap the points out, to electronic. You would be so shocked, by the improvement.
 
Question... Where is your fuel filter and can you see through it ?
If yes, start it up, allow it to warm up to normal operating temp, off choke to curb idle.
Watch the fuel in the filter disappear and idle stumble occur at the same time. then filter fills again, idle corrects. This cycle repeats again and again.
 
Check that charging system real good. Anything that affects the voltage to the primary side of the ignition will be exaggerated on the secondary side. Too high voltage is just as bad as too low in the ignition system.
It's been documented & discussed at great lengths here about the electrical troubles on these cars at the bulkhead connectors etc so I won't go into that now. But well worth checking out.
Also make sure your points are in good condition & all electrical connections there & at the coil are tight & not shorting against anything.
 
Get an in-line spark tester and watch it when it starts stuttering. I ran with one installed for 10 min with no problem, or stop and install it just before you think it will do its normal stuttering. If not a bad spark, it is probably a lean fuel condition, perhaps from boiling fuel if it happens only in the summer (but your winter now).
 
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