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Noswal · 07-29-2017, 10:44 AM

I have a 1978 F100 with a 351w. Kept having problems with the DuraSpark ignition box so I replaced it with a used MSD 6A ignition box and kept the duraspark distributor. When I plugged in the vacuum advance the engine will not accelerate without popping and losing power. I thought that I might have a bad vacuum advance so I replaced it. No change. I replaced the entire distributor. No change. The guy I got the box from said he only ran it a little while on his 4 cylinder import.
Anybody else have any probems like this with the msd box. Is there advance built into the box? Maybe I just have a bad box, but it sure is frustrating.

07-29-2017, 10:44 AM	#1
Noswal Senior Member Join Date: May 2010 Location: Manchester, TN Posts: 186	Vacuum advance/MSD problems I have a 1978 F100 with a 351w. Kept having problems with the DuraSpark ignition box so I replaced it with a used MSD 6A ignition box and kept the duraspark distributor. When I plugged in the vacuum advance the engine will not accelerate without popping and losing power. I thought that I might have a bad vacuum advance so I replaced it. No change. I replaced the entire distributor. No change. The guy I got the box from said he only ran it a little while on his 4 cylinder import. Anybody else have any probems like this with the msd box. Is there advance built into the box? Maybe I just have a bad box, but it sure is frustrating.