I swear Im gonna burn this car to the ground one day. This is the 70 GS. Issue started with the points always needing th be filed and adjusted every 100 miles. They were pitting. Coil only had 4.95v going to it thru the resistance wire too. Couldn't figure out what was going on so I just threw in the towel and put an Crane XR-I. Best thing I did as the car really ran better. Started overheating coils. Replaced the coil with another used original Delco I had. Ran good for a while until the gremlin reared its ugly head yet again. It runs good until the car sits after driving. Once te engine heat soaks for a few minutes, the car gets a misfire at low rpm under load until the fan cools it off. Like when Im taking off from a light. Not sure whats going on. maybe the 4.95 volts is too weak? Could that play a part? its definitely on the low side. My plan for this weekend is to- Carefully take the harness apart and cut back the resistance wire until I get 7-8v. The guy at Crane said the XR-I likes 8v. Install the matching Crane PS20 coil and take my 44 year old Delco out of the equation. Cut the yellow, R wire in the harness so I'm not spiking the Crane with 12v when cranking. Not necessarily a contributing factor, but while Im there
If it were me, I'd get the matching coil and run a 12-gauge wire from a switched source to the coil. That way, I could go back to the resistor if I needed to, although it sounds like the resistor has a gremlin anyway.
Why cut the yellow wire? Can't you just unhook the terminal at the solenoid and tape it back to the harness. Then you can go back easily if you ever need to.
I thought about that. If I cut the wire inside the harness, I can easily make a repair to the wire and reconnect it. That way, the yellow wire is still connected at the starter and looks correct. But disconnecting it at the starter would be easier to undo in the future. Either way, I hope this finally fixes it. Im getting tired of dealing with this issue. I just want to drive it!
had a similar thing happen,the pieces in the ign switch were worn,cauaing resistance,had to change points every 100 mles,iit would run great for 100 miles or so and then start missing and the points were bad,the bad pins in the ign swich caused to much resistance,put in new switch end of problem,might be worth a try
Two things- I believe that bigtorque5 has a line on one possibility, with the ignition switch. I don't like throwing parts at a problem, but how old is the ignition switch? It is also possible that the ignition switch is slightly out of adjustment. Does the car start readily, without turning the key all the way to the stop? For that matter, the rack gear could be worn enough that the contacts in the ignition switch aren't really making a good electrical connection. There is a small range of adjustment in the ignition switch- it has slots on it. The potential from the yellow wire to the coil is not 12 volts (or battery voltage, for that matter) when cranking. There is a pile of voltage drop through the solenoid, so it's pretty close to the voltage coming from the switch through the iron resistor wire when in the run position. Hot coil/burnt points actually sounds more like too much potential...OR high secondary resistance. Primary current draw rises as the secondary voltage requirement increases. The problem with these sorts of issues is that we usually check for voltages when the car isn't running, and the current draw isn't there. Full battery potential minus wire resistance may be present when the key is on without the engine running. The primary voltage being less than 5 is your clue. There is high resistance in the primary side, IMO. One more thought- when the points are pitted, which side of the points has the pitting? One way or the other, it is an indication of a condenser that is over- or under-capacity. Do you replace the condenser when you replace the points? Not everything I have posted may seem to be logical, in the sense that over/under current or voltage may not match up. What I'm really trying to do is throw out some potential possibilities. Remember, I have a concussion, so this may all look like booshwah to me in the morning.
First off, a concussion?? what happened?? Jen had one years ago from falling off her horse. Scary stuff. She was slurring her words and couldn't remember where I worked.... That's really interesting about the ignition switch as a suspect. I would of never thought of that. Ignition switch is adjusted correctly. I never replaced it, so I would have to assume its 44 years old. I hate throwing parts at a car as well, but at this point I don't mind giving it a shot. If that's the culprit, I would assume the voltage at the coil would go up from 4.95 with the new one in place? Right now the car has a Crane electronic ignition conversion in it, so the points are gone at this point. Going from memory, I think the fixed side of the points was getting pitted. and yeah, it was like every 100 miles. Damn, I feel like running out to the garage right now....
Jason, did you try hooking up the car to an oscillope, like one of the old Sun tune-up centers? They supposedly are useful for troubleshooting the electrics. And don't want to get off topic, but I have a Sun 1015 I'm trying to get going if you know of a source for manuals or good on-line info. Sun sold out to Snap-on who don't provide much support anymore. You most likely know someone with one of these diagnostic consoles. I'd bet that would find your problem.
Donor car I'm scavenging for parts, I dropped the driveshaft on my head when I popped it off the differential. The build up on the ground side of the points means the condenser has too high a capacity. Do you have a radio suppression condenser on the coil? If so, make sure it is on the + side of the coil. If it is on the - side of the coil, it can cause the problem you are having.
I used to work for Snap On right at the time they bought Sun. My service van still said Sun Electric on the reggie. 1055....is that the old Sun "interrogator"? I betcha I could fix it! I used to have a 5 gas analyser and dual pattern scope in my garage that Snap On "forgot" to pick up from my house. It was just too big and I ditched it. Those things are hard to come across these days. Anyway, getting back to the issue... Steve- That had to hurt! You must of seen stars. The condenser issue is really moot as the points are now long gone. The condenser on the + side of the coil was gone before I bought the car. I'll look at it again this weekend how that I have some more ideas
Double check the engine ground. Figured you knew somebody that still had a scope, hence my suggestion to hook your car up to one. That's gotta be the best way to diagnose your problem. Here are some examples of what putting the car on a scope can tell you about whether the system is operating correctly: http://forums.corvetteforum.com/c1-and-c2-corvettes/2729439-scope-patterns-2-a.html I'm new at this, but knowing what the firing voltage requirements are, and seeing if the coil is discharging properly after firing might lead you in the right direction. My 1980 or so Sun 1015's scope doesn't do anything. Checked the boards and saw 2 caps on the power supply board that are leaking, so replacing those will be my first step.
It only hurts when I laugh. Or try to pick up something over 20 pounds. Or stare at the monitor or a book (neither of which I am supposed to be doing, as in right now). I had chirping bluebirds of happiness, and Saturn and Jupiter circling my head, just like in the cartoons. Got hit on the left side of my head, so my vision is mostly affected. The right side of my head hurt immediately, so the old wetware pretty much sloshed around in there. I just laid there in the driveway for some amount of time, and then went back to pulling parts. It wasn't until about 36 hours later that the symptoms hit me like a ton of bricks- nausea, dizziness, blurred vision. It's like a hangover that doesn't go away, for almost two weeks now. Doctor says it will be months before I'm fully recovered. How long did it take Jen? Guys, if you are an old man like me (61) be careful with this kind of injury- or not getting it. I've been conked on the head before, but I was younger and don't feel that it took that long to recover. Different ball game, now.
Yikes, that's some scary stuff Steve! Months to fully recover?? wow...When Jen fell off her horse, she hit the back of her head on a log. I guess it all depends what part of your noggin gets clobbered. I remember she spent a night in the hospital. She was in her early 20's then so she bounced back pretty quickly.
Check your coil wire too. I burned out two coils on my Dodge pick up within a few days before figuring out the coil wire was bad causing way too much resistance. It was a fairly new Bosch set of wires too. Just another thoughto No: Oh, and by the way, I always get a kick out of your avatar pic!
Walt you're really going to go there???. . .Asking Jason if he "has a oscilloscope - flux capacitor - Apollo 11 Grumman Lunar Module testing tool?" OF course he does!!!!ou::Smarty:
Jason has every tool known to man. If you show him something he doesn't have, he practically has an orgasm.:laugh: Then, he will buy it off you for much less than you wanted to spend.:Smarty:
Update- I found a big problem at the bulkhead connector. When I pulled it apart today, I found the terminal for the resistor wire pulled out and the resistor wire itself loose from the terminal. Not good. I cant understand how it even ran the way it was. Probably the reason I was only getting 4.95v at the coil when the points were in it. I managed to spread open the terminal, re-crimp the wire, solder it and reinsert it into the connector at the bulkhead. And this time I made sure it was fully seated after I re-installed it. Now, if I disconnect the Crane XR-I, run a jumper to the negative side of the battery and then test, Im getting close to 7 volts. With the Crane XRI wires installed (which has two wires going to the coil), Im only getting battery voltage. ??? What am I doing wrong? EDIT- just re-read the instructions for the Crane ignition. Says to check voltage while cranking. Will do that tomorrow in the AM and report back
Drove it all over today. Stopped at a few places, let it heat soak good and drove it some more. Its fixed. If the problem was still there, it would of appeared by now. The broken/ pushed out wire at the bulkhead connector was it. One other thing I did do was move the heater hose off the side of the coil. The heater hose was always right up against the coil. I imagine the hose would transfer heat to the coil no? While I was messing around with everything, I took a tie wrap and tied the heater hose to the alt bracket to get it off the side of the coil. Not sure of that was a contributing factor or not. I'll eventually get a longer piece of hose so it will stay off the coil without the tie wrap
