I have a 1987 Iroc Z28. It has a 383 stroker crate motor in it, with a supercharger by paxton. It also has an MSD ignition, a vortec FMU. It is a TPI engine.

I just recently changed the spark plugs, and factory coil pack with an MSD coil pack. It already had an MSD ignition box and MSD 8 MM wires. I think also an MSD distributor cap.

It seems to have a big loss of power under load and I can't figure out why.

Anyone have any suggestions?

 

Was the problem there before you replaced the ignition stuff?

 

Yes, I saw spark arching off the coil and wire. That's why I changed it.

 

It actually started doing it, right after I peeled out one time. Been doing it ever since.

 

The spark arching off the coil wire indicates abnormally high resistance in the secondary circuit. Since you changed out wires and plugs, you may want to take a good look at the distributor cap and rotor. Being that the engine is supercharged, the stock gap is probably too wide, so you may want to bring it down to under 0.030".The arching, once started, creates a carbon path which the spark continues to follow, especially under high load conditions when the plug gap is harder to jump. Since the problem started after putting a high load on the engine, make sure the engine mounts are good and not allowing the engine to rock excessively. Long time ago I had a 409 Chevy that would regularly break the left motor mount. This allowing the engine to move and cause the distributor to hit the fire wall, damaging the cap and rotor, resulting in a light show around the outside of the distributor.

 

I think I found the problem. I found one of the spark plug wires arching on the emission pipe coming off the header. I am going to change all the wires and see what happens. I will keep you updated once I do that. Thanks for the help.

 

The plugs are gapped at .035, which should be fine and have no spark blowout, especially since I have a full MSD ignition.

 

Well, I found out why my car was losing power. When I replaced the spark plugs, I must not have pushed one of the wires on all the way. When I lifted the car up in the air, one of my plug wires had come off the spark plug. Although, I did do a full tune up.

New MSD wires
New MSD coil.
New MSD distributor cap and rotor
New spark plugs.
New fuel filter.

It's running better now, than it ever has since I bought it. This car is nasty.