1. HEI in a 350 Chevy. 2. Was messing around tweeking timing yesterday. 3. Today, no spark 4. With trusty dusty olm/volt meter getting 12 volts to dizzy 5. Double checked ign fuse, it's ok 6. I can't tell you how old it is, so whether the module let go, the coil, the coil pick up, or the coil itself. Reading up on trouble shooting, apparently these have a tendency to just shoot ****s with out warning with the module. So. Anything else to trouble shoot? If I have to replace, rather than piece here, and hope, and piece there and hope, Suggestions on whether to go with the MSD, ACCEL Pertronics or which? This is the HEI coil in the cap type. Thanks HellRaiser
Those are pretty robust, but when they die it is usually the module. They are fairly inexpensive, that's the first thing I would go after. Some guy's I know keep one in the glove box just for such a situation...
Odds are the stock hei parts will suit you fine. It is a excellent ignition in stock form. I would check the module first. Find a buddy you can swap parts with so you don't buy stuff you don't need. The white grease that comes with/on the module is important. I am guessing it's the module as I have never had a coil go bad. Let us know.
If it were mine, I'd pull the rotor off and see if it's got a burnt spot under the coil contact. They are pretty notorious for burning thru and shorting to the shaft underneath. Then you might GENTLY pull on the two wire going to the pickup coil to see if one of them is broke in two. The wires flex when the vacuum advance works and sometimes break. If all that checks ok, I'd replace the module. Larry T
I read that about using the Thermal Transfer Compund grease and not that Dielectric grease. This is pretty much what I got out of researching H E I's, that it's usually the module that lets go. Oh well, I wanted to change out the intake manifold anyway, I guess this is the excuse to do it all in one pop. HellRaiser
Larry T, Thanks, I read about that too. Maybe I didn't miss anything about trouble shooting one of these then. Damn electronics, it's hard to look at them and know if they're working or not. I'm still from the caveman ages when a points, condensor and coil worked just fine. Thanks all, HellRaiser
check for corrosion on the posts inside the cap if it has aluminum posts. they get scaley and wont let the spark jump from the rotor.
This is what I was/am reading up on about trouble shooting one of these things. HellRaiser //www.customcl***ictrucks.com/howto/aftermarket_ignition_upgrade/
The parts houses have a machne to check the module. Also, in reference to the pole piece, I've noticed the winding getting loose on a few of them and it seems they fail because of that, don't know why. Don't know why my font changed either!
I'm with LarryT on this one. Little story: During 72 & 73 I worked at a gas station that was one of the major repair shops in our town. We had a contracted US Mail delivery truck that dropped mail at several small town in our area that spent every night at our station. That truck traveled around 300 miles a day, 6 days a week. In the late summer of 72 the old truck (one ton cab & ch***is Chevy) was replaced with a brand 73 model year truck with a 454 and the new hei ignition system (first new Chevy truck with hei in our area). By mid December that truck had over 100k miles on it already. One day it came in on a tow truck, no spark. Our machanics spent hours trying to figure out how the hei worked so they could get the truck running. Keep in mind, places like NAPA didn't even have replacement parts for these things yet. We phoned out to the largest, best equipted, local Chevy dealer (also the ones that delivered the truck) and were told we were on our own, they have not had any problems with the hei, but of course they never seen any of them with the miles this truck had on it already. They gave us the # for GM Tech in Detroit. After going through the check out proceedure and still not having a running truck, GM Tech told us to let them know when we got it figured out! There were three qulified mechanics scratching their heads + who knows how many at GM. Out of frustation they let the high school kid take a look at it. Quite by accident I flipped over the rotor, something didn't look right. It had a dark spot just off center on the bottom side. I made them get me a rotor. They went over to the Chevy dealer and pulled one off a car in the show room! Put it on the truck and instant fire. Over the next few months whenever a new GM car quit running it was drug into our shop and 90% of the time the rotors had burnt though. Replaced the rotor and they would start right up. Our shop began the practice of replacing the rotors on GM cars with every set of plugs. That GM rotor thing is probably my only claim to fame and I didn't even get the credit for it. Oh well, such is life. Gene
Ok, here is the scoop. See if you have a ground pulse to trigger the coil, if so, check the cap, rotor and coil. If not check the pick-up, you should see .3v AC when it is spinning and disconnected. If that is present, connect the pick-up and use a test light from batt+ to trigger the module and see if it fires the coil. You will have to be creative to keep everything wired and check for spark from the coil, but you will know exactly where the problem exists. Word of warning, cheap modules aren't worth the time to bolt them in.
Go back to your basics first......... you said you were messing around with timing, could you have knocked a wire off? Seems like a long shot to me that a burned rotor would happen right when you messed with it, right? What everyone else said is valid, only the problem occuring right when you adjust the timing is strange.
Yep, double checked for the 12 volts. When I say I was messing with the timing, I put the vac gauge on, and timing light. Timing was on, so used the vac gauge to get highest reading, then backed down about 1/2 inch of vac. It was pretty much right on in the first place. Doing good, so I zapped the throttle a few times, sounded good, and good response. Shut it down, Went out later to retart, zip. Used the timing light, and stretched out the line so I could watch for a lite while I turned the key, No light from the timing light. HMMMM. I tried turning the dizzy a fraction one way retard to try and start, nothing,, turn to the advance to try and start, nothing. That's when I put the Olm/Volt meter to the wires, got 12 volts. Just about 30 min ago I used one of those little 12 volt trouble lights, lights up nice and bright. As far as putting the clip back in the dizzy, there's just about only one way for it to fit back up in there, as the left hole is for a tach, which I'm not running. This is one of those times when it would be good to have a helper, a good son/daughter or a good Mrs. to lend a hand Oh I'll get it, just trying to make sure I covered everything before I do have to take the Dist out. But thanks everyone for the suggestions. HellRaiser
I'm not sure how or why this happens with my HEI but the car will start maybe 6 to 10 times no problem and run fine. Then the next time I try and start it, it will not fire, no spark. I take the cap off, wipe off the rotor tang and ****on inside the cap,(I know this sounds stupid) put the cap back on and it fires right up...for about 6 to 10 starts. ?????? anybody? anybody? DD
Don't take the distributor out yet. Get a chiltons or haynes that tells you the Ohm readings for the pickup and high voltage coil. Test em, if all looks good, take the module to a parts store, they test em for free. My 20 years of HEI head-scratching says that 95% of the no-spark failures are module or ignition coil. Very rare to lose a pickup coil. Actually more common to have the high-voltage coil test good, but actually be bad. Had that happen a few times. Replace your cap and rotor every 50K with quality pieces to avoid any rotor problems as described above. I've personally never run across it, but also replace my cap/rotor immediately upon buying a car, and have taught friends to do the same if they expect repair and troubleshooting help. Is there any chance you hooked the distributor power wire to the tach terminal next door? Even momentarily? good luck Edit.... since you asked about replacement brands. I've known several near-new mallory HEIs with issues and don't recommend them to anyone. We fought a misfire in our HEI-mandated stock car for a while until switching over to Davis Unified Ignition HEIs. They'll rev crisp over 7k, and between us we have a half dozen of em including in street cars. Not a single failure of any kind within the group.
Shify. I had one of those Davis Unified Ignitions in a 66 Galaxie with a 289, I agree with you, that is one top notch unit. As I remember, you'd give them the specs of the engine and cam, and they'd dial it in for you. It was a no fail system. HMMMMM....Push come to shove, that might be the best way to go. AGAIN.... Thanks for the reminder, as a matter of fact, I need to look around thru my spare parts pile, I think I kept it. Too bad it won't work on the SBC. Thanks again, HellRaiser
Someone told me there was a difference between the GM module and an aftermarket auto parts store module, the difference being a patent issue. check the wires to the coil and carry a spare module.
When a car you have been working on fails right after you worked on it...be real, real su****ious of everything you did. And also of any new parts...
A very short up date on what's transpired so far. I went and tried to start it again today, I thought maybe it would have fixed it's self over night, but it didn't. 1. Cap seems good, it has the br*** posts, so there was no corrosion. 2. Rotor, other than a very slight amount of dirt, no burnt spots 3. When I took the module out, there is still white grease on the pad, but it's not really evenly spread out, very slight corrosion on the edges of the pad. 4. On the two trigger pick up wires, they were tight and very slight corrosion, but appread they were getting good contact. I'll have to wait till tomorrow to go into town to a auto parts store, to have the module tested. For what it's worth, the cap, rotor are Standard brand, the module has 6FD printed and another number 9750, that looks like it might be a date of mfg. I don't see any mfg marks though as to who's it is. When I go to town, Speedway is open in the morning, but I'm sure they don't do any testing of the modules. They do sell MSD products for rebuilding. There's O'Reily, Auto Zone, and one more auto store, I can't think of the name. I hate to go there, only to have them check the module, and not buy any parts from them though. When I was in the big city yesterday, the O'Reily store said they sell Borg Warner Dizzy's if I went the who ball of wax, but they are rebuilt stuff.. More than likely, I'll just end up replacing everything under there, rather than piece meal it. Cap, rotor, module, coil. Sort of like the old, and some of the still, when you do the plugs, you'd replace the points and condenser at the same time. The long range weather forecast is for good weather up at Hunnert next week, a bit cool, (so what's new) Debating on whether to take this roadster, or the usual HellRaiser Ah the drama continues, but I'll give an up date later on how things turn out. Hellraiser
You can test the pickup and hi voltage coils as follows Pickup coil should have 500-1500 ohms resistance between it's 2 wires. Now check resistance between each wire and the distributor body to see if it's shorted out, if you find continuity to ground, it's bad. Hi voltage coil- still with the coil installed in the cap, check the resistance between the "bat" and "tach" terminals. Should be very little resistance, like half an ohm. Now check from the rotor ****on inside the cap to "tach" and then to ground (center of the 3 posts the pickup coil wires clip into) Actual resistance will vary depending on the coil, but you do not want to see an open circuit. good luck
Here's a pretty good writeup on the HEI system. Step by step. http://www.chevelles.com/techref/ftecref5.html
At least get the Borg Warner GM would be better . If you decide to replace everything can't you buy on of the major brands new for about the same money ??????
I bought one of those cheap *** china GM HEI's at the local swap meet. New in the box for 50 bux. It lasted 15 minutes before I lost fire on it. That was yesterday and today I bought a GM HEI from C'list for 30 bux, stabbed it in and it fired right up. Once on and old Z28, I replaced every part on the distributor trying to get fire and it turned out to be the carbon ****on.
G.M. Hei distributors do not have a ground wire. When you loosen up the holdown you can lose the ground and ruin the module.. Buy a new module and hook a ground wire to the dist body and motor.
I had the same happen to me last weekend. Car was running fine, turned it off and tried to restart it and got nothing. I haven't done any trouble shooting yet but I expect its the module. I have had a similar problem on Camaro's in the past and it has always been the module.
Go to your local wrecking yard (I go on $45 dollar day...all you can carry for $45) get several of the GM HEI's. Use parts from one (if you really need to find out what let go) and toss the other in the trunk (after verifying that it does work). I personally have not had one fail, but just in case I always carry a complete spare in the trunk (in all three of my cars). Original GM HEI's are cheap ... save yourself the trouble and just replace the entire unit.
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