OK, trying to get my '68 el Camino to the track.....

http://www.chevelles.com/forums/showthread.php?p=900635&posted=1#post900635

and have run in to a bit of electrical trouble. I keep blowing ignition fuses. It started about a week ago, I went for about a 5 minute drive, shut the car off with no apparent problems. 10 minutes later I try to start it up and it will crank but not fire. Hmmm.... Check the usual suspects and sure enough my ignition fuse is popped. No problem, put in a spare fire it up and drive 5 minutes home. I've been on several 5-10 drives since then with no problems. Then last night, I'm taking the car out for some last minute "shakedown" runs before my first trip to the track, I'm cruising down a smooth stretch going about 40MPH and the engine loses fire. Hmmm.... guess what I checked first? Yep, the IGN fuse (20Amp) is popped. No problem (I think to myself) as I reach for a spare and pop it in. Crank, Crank, Crank..... no fire. Hmmm.... check the fuse, it's popped. Open the hood look for any signs of a short and nothing apparent. Try one more time to replace the fuse (hoping for a miracle) only to get the exact same result.

So, am I looking for a short or is the ignition somehow "overloading" the fuse. I'm electrically challenged and would appreciate any help. Thanks in advance!

check all your ignition wires. like follow them to the distib. you may find a vary bad ground, or a wire is shorting out causing it to POP as you say lol. i had the same thing happen in my 72 chevelle, my fuse blew for ign. awhile back, and i had a bad ground.
is it a resto car? or an original? sometimes wire go over time

Check the hot wire to the starter & solenoid if you have headers. Might be touching/melted.

First, what kind of ignition ( MSD, stock HEI, modded HEI ect...) do you have and how is it exactly wired? 2nd do you have anything "extra" thats wired on that same circuit. You could have a short, or you could be overloading it, need more info to give a answer.

Happy to give more info :) MSD Pro Billet Distributor, MSD Blaster 3 coil, MSD 6AL box. 6AL box is wired per instructions. From the IGN spade on the fuse block I've got a jumper wire running to a Power distribution block from MAD enterprises (CN-1). That is where I've got the MSD box tied into the ignition circuit. I'll have to check and see what else is connected to the CN-1. I may have my thermostat that automatically turns my fans on hooked to it too. My fans are both run off their own relays. Does this help? Thanks for the help!

*EDIT* One side of my thermostat is hooked to the CN-1 that is powered by the IGN spade on the fuse block. Also on the CN-1 is the small red wire from the MSD box, and the small red wire from my TACH. Is this enough to OVERLOAD my IGN circuit? I think we're on the right track with the thermostat because the only time this has happened was when the car heated up enough to automatically turn the fans on......

OK, it is my thermostatic trigger (for my electric fans) that is creating the overload. I pulled the wire running from the side that is connected to the IGN source. put the fuse in and it fired right up and ran no problem. Drove it from my Dad's house a few miles where it heated up to around 185 (fans are set to come on at 180 but now unhooked) to my house with no problems. Turned the car off, plugged in my wire from the IGN to the thermostice trigger. Leaned down so I could see the fuse, then turned the key on. Guess what, the fuse blew. Here are 2 pictures. The first is how it should be wired with no manual switch, the second is how I've got it wired so that I can run the fans by a manual switch with or without the key on.... Don't laugh, like I said I'm no electrical expert. I feel my problem must be related to how I've got this wired. Any help is appreciated. thanks.

http://www.chevelles.com/showroom/data/500/thermostat-wiring.jpg

http://www.chevelles.com/showroom/data/500/medium/Fan-Drawing.jpg

Since it is blowing the fuse after the T stat turns on the fans on, the problem has to be there. The trigger part of this circuit and the MSD6al small red pull very little power. There could be several reasons. First check the lighted switch. With a meter check that power is not going to ground, through the switch when the T stat closes. You can also take disconnect the lighted switch temporary to see if the problem still exists. I would try this first.

removed the ground wire from the switch (which makes the switch light up when on) and the problem went away. Thanks everyone for helping!