lynkite Posted May 21, 2009 Share Posted May 21, 2009 here is what's up. http://www.zcar.com/forums/read/1/2051380 help! Quote Link to comment Share on other sites More sharing options...
Tony D Posted May 23, 2009 Share Posted May 23, 2009 Go get a new module, properly ground it through the bolt holes first THEN apply power and start troubleshooting. And consider testing with somthing more advanced than a test light. the 0-5VDC scale is more than resolute enough to verify CAS and ECU input/outputs for the sake of proper triggering at the last link in the chain (the HEI Module)... Quote Link to comment Share on other sites More sharing options...
lynkite Posted May 23, 2009 Author Share Posted May 23, 2009 so the actual holes in the module, are the grounds, and not the actual ground wire running out of the module itself? Quote Link to comment Share on other sites More sharing options...
Tony D Posted May 24, 2009 Share Posted May 24, 2009 They are a different ground. One is a reference for one circuit, the holes are ground reference for the power transistor and internal circuitry. Without the holes grounded, voltages inside that module go on spiking frenzies, and toast the internal components "toot-sweet"... When I was working at a GM dealership in 79 and 80, the one thing the GMI guy giving the HEI Training stressed was to NEVER power-on an HEI until the module was BOLTED DOWN (with the heat-transfer grease of course!) The other thing that kills them is heat, either from not greasing the base, or insufficient heat sink in aftermarket applications. I have mine on an aluminum plate that is 5X8 and it STILL gets HOT to the touch. You want surface temperature to be below 145-150F if at all possible. Inside the distributor isn't the greatest place to put these things, but I guess the boys from GMI didn't want to copy Chrysler, who bolted their HEI Module to the firewall....a BIIIIIG heat sink! BTW, both the metallic bottom and the metal 'rivets' through those holes are connected, and are all the same common ground plane. It is totally isolated from the circuitry that the "Ground" wire is hooked to...which is part of the reason these things go bad so often...people don't see much about it other than 'bolt it down'---they never get the whole GM explanation of WHY it needs to be securely fastened to the chassis ground. Many times, you can find grounding straps on HEI dizzies that had issue with intermittent spark---someone was under the impression that an aluminum dizzy base bolted into a cast iron block might not be grounded properly (apparently Nissan thinks this as well, as they have a Factory applied ground strap!)... Generally on a Chevy though it was an issue that the HEI was intermittently taking a dump because of heat. Nobody drilled holes in the cap and let the air cleaner pull air thorough the cap to keep cool air circulating... ooops! Someone did! If you are using a four pin HEI (or ANY HEI) and insist on running Autozone or aftermarket crap cheap modules, KEEP A SPARE IN THE GLOVE BOX! I went through three or four HEIs from Autozone before getting one that WORKED RIGHT. That is the one in my glove box as the roadside spare. I put a Per-Tronix Flamethrower on because I didn't like the weak spark of the AZ Crap. It was a whole $40...no big deal there and I have the satisfaction of knowing I have parts that clearly say 'For off Road Use Only, Not Highway Legal' on my streeter! LOL Thing to take away from this is there are TWO ground circuits on a GM 4 Pin HEI. And the one through the BOLTS is the CRITICAL one, if it's not connected...YOU FRY IT! Quote Link to comment Share on other sites More sharing options...
lynkite Posted May 24, 2009 Author Share Posted May 24, 2009 so how can I know that I fried it? lol. It never did get hot. How can I be sure that it's toast? Quote Link to comment Share on other sites More sharing options...
Tony D Posted May 25, 2009 Share Posted May 25, 2009 Power it on, leave the power on. If it doesn't get hot...it's toast. Another big indication is not being able to get any spark when you gate the appropriate terminals with voltage...like you are mentioning. All it takes is a second ungrounded, and POOF. Go get another one. When I was doing it, there were old-timers complaining because 'points don't take a crap like that!' They were used to being able to leave power on for a while to do testing. I don't know, maybe their brains worked slower. A lot of them didn't comprehend when the Simpson didn't deflect, no matter how you try it...it means there's nothing there! And those Wells Aftermarket Modules are sh*t crap junk. I KNEW what I was doing and STILL three of them fried or were bad right out of the box! The fourth was a heat-soak victim from power on too long in the wrong trigger position. But #5 was the lucky one. And I only paid $13 for it, every one was 'back under warranty' with me griping for the time it was costing me. I actually picked up the one that WORKED on my way to the speed shop to pick up the Per-Tronix Module because I was sick of the cheapo stock replacements. As I understand it some of the performance aftermarket modules use much higher grade components, and are far more tolerant of power on mistakes. But even they will fry without casing ground. It just takes a few seconds longer. Quote Link to comment Share on other sites More sharing options...
Tony D Posted May 25, 2009 Share Posted May 25, 2009 Searching Google turns up a lot of the same information... http://www.chevytalk.org/fusionbb/showtopic.php?tid/206114/ Quote Link to comment Share on other sites More sharing options...
lynkite Posted May 25, 2009 Author Share Posted May 25, 2009 wow....you are like...a HEI master. I should have came to you first. lol. oh well. I'll go get a new module. Quote Link to comment Share on other sites More sharing options...
Tony D Posted May 26, 2009 Share Posted May 26, 2009 No, I was just around in 'the bad old days' of HEI. Apparently not much has changed until they went to the new crankfire systems. Quote Link to comment Share on other sites More sharing options...
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