Help... Ignition ECU issue???

[Prostreetmik]

So I have a 1964 Sport Fury... stock internal 440, stock 906 heads, 484/284 cam, performer rpm intake, 750 Holley... Electronic ignition conversion i found online, 3000 converter, 4.10 gears, etc...

Ran good, but figured out that the ECU box it came with was orange, but not the mopar orange box. SO... I bought a mopar chrome box... Thinking it would obviously run better... right?

Well, swapped them out, and after 4000 rpm, it starts to pop through the exhaust... and now a day later it has developed a miss. Like its fouling a plug... it comes and goes at the right throttle position, but when I hammer it, it is missing...

So, I need help from my mopar friends... PLEASE let me know what could be the issue. I have not messed with it. Parked it, scratched my head, and walked in to post this.

ALSO - What spark plugs should I be running? I have a set of expensive Iridium plugs in it now... and like I said, it seemed to run pretty good before I swapped boxes. Car weighs 3800 lbs with me in it... ran 13.29 @101...

Please sound off...

 

[Prostreetmik]

Could the new Chrome ECU be the problem??? Or could it be something else???

 

[Sixpactogo]

Make sure the box is grounded good to the firewall. I had one that would overheat and shut the engine down completely after running fine for an hour. Turned out to be a bad ground.

 

[Prostreetmik]

UPDATE -

Switched the boxes back out, and same problem... so I pulled the cap, and it is a mess.... so maybe it was just a dumb coincidence that it happened to go south when I installed the chrome box...

So Ive ordered a mopar cap and rotor, new wires and a set of new RJ12YC plugs...

We will see if the problem goes away.

 

[hangn0ut]

I think you got it covered. Ought run good. 13.2@101 is quick for that mph.

 

[Prostreetmik]

Whew!!!

Changed the cap, rotor and wires... and in the process found two wires that were in bad shape... (only a few months old too... ) So I went to the new Ceramic Accel wires... BOOM... back in business... and the chrome box is great!!!

Thanks to all of you that chimed in... Im so glad it was simple...

 

[hangn0ut]

'Dumb coincidence' happens a lot when you play with cars. But you took care of your business!