MSD Question

Hi all. I Realize this isnt a Nova forums, but there is never anyone on the Nova forums, and this isnt really a "Nova" question anyway.. so hear is the story. About a week ago my car started runnin very rough. But the weather had changed from cooler to really hot, so I though is was my Holley Carb because they are very tempermental and all. I did a little adjusting on it and it ran fine until yesterday. Yesterday i was driving down the highway at around 45 and my car backfired like HELL. I mean this wasnt a "regular backfire" This was like gunshot by your ear unbearably loud backfire. It did this two times in a row and then the car killed, while I was going 45 down the highway. I was able to coast the car into a gas station, and got out and started looking under the hood when a guy on a bike rode by me and he said he saw the whole thing and that when it backfired around a 5-7 foot flame shot under the bottom of my car. With that being said i started checking for spark and found that I had none, so i assume the flame came from gas building up, then catching a spark and igniting. Would any of you have any ideas on the problem. I am not 100% sure, but around 95% sure that something is wrong in the MSD box. When deciding to buy one, I had read a few reviews about people having similar problems with their boxes. My question is does it sound like that could be the problem? And if it is should I put another MSD box on, or spend my money on some other 200 dollar upgrade? In all honeslty I didnt notice any difference Pre and Post MSD box. The MSD box is under warranty for another 8 months or so, so time isnt really an issue. I would just appreciate any/all opinions as I have come to respest all of yalls opinions. Thanks
Rob

i cant really say that i know what was causing it but i know what you mean about the backfire. my dads 68 caprice didnt have spartk one time when he was trying to start it and then when it finaly got spark, after cranking if for like 30-45 seconds, it lit all the gas and was basicaly a bomb. i was about 4 feet to the side of the car kneeling down and the concusion nocked me over. it also blew the back of the muffler off. so you might want to check to see if anything has been damaged. but it sounds like your right about it not getting spark for some reason. did you check your plugs?

I checked My plug wires where that go on the plugs. I wasnt getting any spark their, so its somewhere back along the line. I will really lok at it in about 2-3 dayd after these 16 hour work shifts, but Im just tryin to collect ideas right now that i can try. Thanks for the input

ROb

timing chain

Very doubtful its the timing chain.. the timing chain was replaced around 3 months ago with a comp cams double roller when i put the new head.intake/cam combination in. Thanks for the suggestion though