87Stallion

I just installed a MSD 6A box. I wired it according to the diagram for the duraspark dizzy that came with the BOX. The car idles ok but now has this bad hestation and feels like its missing in HIGH RPM. I am running a Petronix Coil. Any ideas on what could be the issue???
The wires are new and so are the plugs, cap and rotor.

87Stallion

Update. I installed a MSD Blaster coil about an hour ago. I took the car for a romp and its breaking up bad around 3000-4000 RPM. All the plugs are good and gapped correctly. (.054) I hate to have to put the damn Duraspark box back in after dropping the cash for a MSD box.

93hatch306

every time I've had an MSD go, they just quit. check the dizzy....could be worn out. that'll cause the symptoms you're describing.

93_five_oh

do you have the right plugs in?

i put colder plugs in a while back (just autolite 24's, stock is 25) and it missed like none other. i put motorcraft plugs in and it runs great again. it missed through the whole rpm range though, so that might not be your problem.

87Stallion

I run Autolite 765's as I have GT40 heads. The plugs and wires are brand new. I just got back from the track and the first run it went like a bat outta hell and the 2nd pass it broke up bad at 4000 RPM's. I know know if the MSD box is getting hot. I have it mounted where a EFI car's air filter would be.