Hello all, I'm in a state of complete confusion! First off I just put my engine back in the car after 14 months of resto, I set to about 6-7 degrees btdc, after seting up ignition, rewiring starter and a mess of other things that the po destroyed I got it to fire. And it ran great! Now still I have yet to put it in proper time, adjust the carb ect. Now this is where it gets interesting. As I said before it ran strong, then all the sudden it started running really rough then would die, would crank and crank and no fire. It cranked so much that it flooded. The next day after pulling the plugs and clearing the excess fuel, it fired up for about 25-30 sec. Then died(ran rough) then just cranked and cranked! So I know I am getting plenty of clean fuel with two brand new fuel filters. So I thought it just might be the coil, pulled #1 plug put a spark tester on it and had spark( was kinda weak) so I went ahead and popped in a new coil. The new coil had much better spark but still no start. What is the deal? It will start if it sets over night, but won't even start with starting fluid after it dies. Would the ignition module cause random no start, running rough? Or mabye the pickup coil? I would think that if these were bad the car would not run at all,right? Please help me, I'm so lost and have recently dumped over 2k into the drivetrain

 

Starts great cold . Runs a bit then dies . Won't start till cold again . Repeat . That is the classic definition of ICM failure

 

Thank you for the quick response, but it does start, but runs really rough until it dies about (25-30 sec give or take). So what you are saying is that ones it runs for that period the icm just takes a dump? Even though I still have spark? And if that is the case what would be a proper replacement ac/delco, accel, msd, ect. It is a summit billet dizzy. So should I run summit parts? Also it does not have a ground strap from the distributor to the block/firewall, will that cause the Icm to fail faster?

Thank you for the information, it is much appreciated!!

 

Myself , I go for the AC Delco , but brand preference is not much of a consideration here . As to the ground strap , couldn't hurt , that's for sure , but if the distributor hold down bolt is properly tightened that should be good enough ground . The common failure modes for the ICM are either that it just outright fails , or does what your's does , run for a certain short time and then quit till cooled off . One other thing I wanted to mention to you is , that yes , our eyes most certainly tell whether a spark is present , but have no way to determine if that spark is proper for the engine without a "spark gap tester" . Thing is , a spark that will jump a fair distance in free air may not have the energy to jump even the needed 1/8" of the sparkplug's gap when asked to do it in the pressurized environment of the cylinder . The higher the pressure , the more power needed to jump the plug's gap . The spark gap tester is designed to mimic the actual environment the spark is being asked to occour in and so is the best indicator of if the spark is proper or not .

PS , when you get the new ICM , pop over to Radio Shack and pick up a small tube of their best "Thermal Compound" (sometimes called Heat sink compound or thermal paste) and use that instead of the little tube of garbage that comes with most replacement ICMs . Heat is really the #1 killer of these , and the better paste helps draw the heat from the ICM better than the cheap supplied goo the ICM manufacturers give out . Just make sure to clean the didtributor's ICM mounting surface down to bare metal and then use just enough thermal paste to squeeze out maybe 1/16" when the ICM is tightened down .

Good luck with it