Mad box
 

Experiencing a problem where car wont pull over about 5500rpm. Lays over and starts busting up, lol. 7al2 box, took out rpm chip, no help. New cap rotor and pickup but didnt see anything wrong with any of it. Msd dist is not locked out. Goes to 38 degrees by 2500. Its not fuel or carb. Tried different carbs to no avail. Think I have a ignition box issue. Big question is if I get a new one I want to be able to use it with a holley fuel injection system. Recommendations?

Re: Mad box
 

My car was running exactly like that. It was a loose ground to the fuel pump relay.

Re: Msd box
 

I just realized title said mad box ....bahahahah

Re: Mad box
 

"jamie2370", keep in mind that your "Mad box" box draws one amp
of current for every 1000 RPM.
Take a close look at your electrical regarding the "Box".
Terry K

Re: Mad box
 

Had a issue very similar to yours, seemed worse under a load, driving down the track. The gear on the end of the distributor was worn bad. Installed a new gear and problem was eliminated.

Re: Mad box
 

You are just Mad because sometimes the boxes Make Sparks Disappear.

On a more serious side the local speed shop here has a device they can test them with, however and see if they at least throw a spark.

Sometimes you have to just replace the box to know for sure. If it was not the box you at least have a spare going forward.

My son had one of the 6 series (I think) analog units. I swear in the MSD trailer you could have welded with the thing. Twice they said nothing was wrong with it. It had a slight high rpm miss. However you could replace the box and the miss would go away, put the box back in and the miss would return.

Re: Mad box
 

Hope this might help. Years ago at the Gators I was told by the rep. for MSD to change the coil wire from time to time as the conductor will break down. This was discovered when pro stockers were having ignition problems. John Kissel K242

Re: Mad box
 

In other words: the internal wire is going bad. Should you not see this with an ohmmeter?

Re: Mad box
 

The typical spark plug wire used today in some of the racecars should be a magnetic core with radially wound monel wire wrap around the core. Unfortunately quality is all over the map. Many wire sets do not follow the original French patent of using a magnetic core....problems abound when decreasing manufacturing costs. The coil wire sees more energy per time than do the individual plug wires and over time the wire condition can break down.;) Higher distress happens when underhood header heat and wider spark plug gaps are applied.:cool:



An easy way to keep track of the secondary wire condition is to log (record) the resistance (Ohms) when the set is new and periodically re-test it and compare to the base log data. Another easy way is to run the engine in total darkness and look at the corona discharge at each end of each of the wires. This glowing corona discharge will grow over time and is a decent indicator of when one should consider changing wire sets.:D



Regards to All that like this kind of stuff,
HB2
Dissident:)

Re: Mad box
 

just had this same issue car wouldn't run over 5 grand and was load sensitive ignition box was the problem also 7al2 went to a grid and problem was gone.