banzai510(hainz) Posted October 13, 2011 Report Share Posted October 13, 2011 a ballast resisitor shouldnt get too hot.That I know of . But if key left on I guess it could but I never notice them to be HOT myself so this could be a concern. Points suck. I put new points in the past and would get no spark. But the old back in and it would run. then put the new back in and it would run. SO i figure I installed some thing wrong.. Try leaving the cap off the dizzy and ck the coil wire comming out of coil to ground and see if sparks. Then put cap back on and see if sparks then you know soemthing is getting pushed inside the cap to gorund the coil out. also feel the coil if getting HOT also. Quote Link to comment
Laecaon Posted October 13, 2011 Report Share Posted October 13, 2011 And monkey, you can still have dizzy problems with a matchbox. I mean their is the stator and ring, which then sends the signal to the matchbox unit, which then tells the coil to fire. Quote Link to comment
metalmonkey47 Posted October 13, 2011 Author Report Share Posted October 13, 2011 click for video Quote Link to comment
banzai510(hainz) Posted October 13, 2011 Report Share Posted October 13, 2011 going by the vid it sounds more carb related. since this is a new vehicle. I would do a basic timming ck with a light if you think its off Put to TDC and ck the dizzy rotor laction and hopefully its right on #1 plug wire incase this ids off a tooth or soemthing. I would do a lvalve lash ck and while at it ck the cam timming. by now hopefull the point gap is cked. to me I would see if the accel pump on the carb is worrking ,Is is squirting in gas when you cycle the linkagea???? this would be a big clue,put a new fuel filter , ck the old one cut it open and look. take the aircleaner off and ck the 2nd side also make sure its closed. 30min job brother!!!!!!! Quote Link to comment
bilzbobaggins Posted October 13, 2011 Report Share Posted October 13, 2011 Damn dude, my 620 is doing the same shit. And it started raining here while I was working. Mines a 75. It will run like yours on idle, and will not take off. Mines got a weber. I was unbolting the carb(gd egr runners are in the way, finally bent a wrench to get in there), and the rain came. Think mines carb and timing, the timing plate is maxed out one way and will die if I adjust back the other way. Im going to clean my carb and see what happens. If that doesnt take care of me, Im putting my spare ei dizzy in. Ive got new plugs, wires and points on this one. Let me know what you get. Your truck looks nice too man. Mines a rust museum! Jeff Quote Link to comment
metalmonkey47 Posted October 13, 2011 Author Report Share Posted October 13, 2011 (edited) Whelp, I would check timing but now it's not running at all. Dizzy agrees timing is at least close. Valve lash is correct and cam timing. Verified point gap as well @ .20 As far as carb, it actually doesn't appear to be giving any fuel when the accelerator pump is pressed. I pulled it out to inspect and looked brand new. Sealed nice in the carb too. The sight glass verifys a full float bowl. I can spray starter fluid in the carb and it still won't fire, so I'm wondering if I have a combo of problems. Gonna go take a brake and eat some food. I'll be back at this in a few minuets. Edited October 13, 2011 by metalmonkey47 Quote Link to comment
datsunaholic Posted October 13, 2011 Report Share Posted October 13, 2011 Not to make it overly simple, but when my '76 started doing this, I went through a ton of hassle. Turned out the coil was shot. It'd work when it was cold, but warm up and it'd go out. But I've had it ALL happen. Bad wires, wet caps, blown (shorted) condensers, wobbly dist drives (that made it backfire randomly and under heavy acceleration). HOWEVER... if it would idle but not rev, I had that problem too. Plugged main jets. Got water in the fuel, and that sat on the jets and emulsified. Idle circuit still had useable gas for a bit. Quote Link to comment
metalmonkey47 Posted October 14, 2011 Author Report Share Posted October 14, 2011 (edited) Not to make it overly simple, but when my '76 started doing this, I went through a ton of hassle. Turned out the coil was shot. It'd work when it was cold, but warm up and it'd go out. But I've had it ALL happen. Bad wires, wet caps, blown (shorted) condensers, wobbly dist drives (that made it backfire randomly and under heavy acceleration). HOWEVER... if it would idle but not rev, I had that problem too. Plugged main jets. Got water in the fuel, and that sat on the jets and emulsified. Idle circuit still had useable gas for a bit. I'm sure that it's TONS simple here. I think it's just stupid that I have this crazy problem. I've been through everything short of swapping dizzys and carbs. I pulled the plugs, and they were full of crap even though they were brand new. (Had lots of crappy gas in it when it sat) I swapped the coil with a spare I have and it still won't run right. I'm just going to swap coils tomorrow anyways with a new one and see what It does. Also have a condenser coming and carb kit. I think at the same time, I'll pick up some new plugs and see how it runs. Sucks that I just got it and already have to tear it down :( I also found that the gas tank is leaking a bit. Haven't found where yet. Edited October 14, 2011 by metalmonkey47 Quote Link to comment
banzai510(hainz) Posted October 14, 2011 Report Share Posted October 14, 2011 If you get a coil make sure its for the year specfic Not no EI coil or a MSD coil. That will only make it worse!!!!!! But you said it gets HOT. maybe almost better to start with a new set like you say.Coil and matching ballast but if ballast not avail then just get the coil Like Datsunaholic said the coil could be cutting out(cooking/Hot) Another Key here is you said the Accel pump isnt pumping gas when you cylcle the linkage. Thats the FIRST REAL CLUE!!!!!!!!!!!! bilzbobaggins If your dizzy is cranked all the way to one side to run either the timming plate isnt centered correctly(there is a 8mm bolt under neath where you can adjust the timming plate to the dizzy) once set then you can readjust using the mount/pedastal. In this case I would put motor on TDC Zero and look where the rotor points. and see if centered. Quote Link to comment
metalmonkey47 Posted October 14, 2011 Author Report Share Posted October 14, 2011 Well, when I looked at the carb, it was hard to see, so I'm not 100% about it yet. Either way, I went ahead and ordered a new kit that I'm picking up later today along with an Accel OEM style coil. I put in new plugs earlier because I found the previous ones were black and probably not helping (if anything, they WERE the problem) and broke a wire putting it back on. The wires were a super cheap set of Beck/Arnley wires and fell apart, so I'm going to slap on some new wires in an hour or so when I have a ride to the parts store to get 'em. Until then, I'm working on a fuel tank leak that's a PITA! Quote Link to comment
metalmonkey47 Posted October 15, 2011 Author Report Share Posted October 15, 2011 New coil, condenser, plugs, wires, and still no start. I have spark at the points, but still not at the plugs Just to confirm, blue = + and white = - on coil? Quote Link to comment
metalmonkey47 Posted October 15, 2011 Author Report Share Posted October 15, 2011 (edited) 12V into ballast resistor, and 6V @ the coil. Ballast resistor is HOT! Measured 130 degrees. Far from correct. Replace? I have a spare MSD .8ohm resistor. Edited October 15, 2011 by metalmonkey47 Quote Link to comment
datzenmike Posted October 15, 2011 Report Share Posted October 15, 2011 '74 620 Black/White (ignition ON) goes to one side of the ballast resistor. (this provides about 8 volts to the coil engine running) Black/Red (ignition START) goes to the other side of the ballast resistor. And a wire from there to the + side of the coil. (this provides 12 volts to the coil while cranking the starter for stronger spark) Black/Blue comes from the coil - side and goes to the points in the dizzy and to ground there. Ballast resistors get HOT! Too hot to touch if key ON and points closed with engine not running. Will run cooler when running as the points are opening and closing.This is why they are made of ceramic material and mine has a small metal shield so you can't burn yourself. Quote Link to comment
metalmonkey47 Posted October 15, 2011 Author Report Share Posted October 15, 2011 Mike, I think you have the wrong wiring diagram. Mine's a '76. Here's my wiring @ coil. I have a heavier gauge black/red coming to a 3 way connector. Theres a red/black there, but it turns to blue/black and runs to ballast resistor (see pic above) Quote Link to comment
banzai510(hainz) Posted October 15, 2011 Report Share Posted October 15, 2011 I have spark at the points, but still not at the plugs ck it at the end of the coil. Leave coil wire out and ck the the chassis of the truck.. Dont worky about at the plugs right now. If you have it at the end of the coil wire then the dizzy routes it HOPEFULLY to the correct spot. You can figiure what is the correct wire 12volts ON goes to the ballast 12volt start goes to +coil/ the other wire goes from the other side of ballast to the +side coil. then is when the key snaps back to ON it will run thru the ballast and to the coil. cl the fuse box if fuse is very warm also, clean connectors there also. Quote Link to comment
datzenmike Posted October 15, 2011 Report Share Posted October 15, 2011 MM your pictures look correct. If you have spark at the points then you should be gettin a high volt spark from the coil wire to the dizzy cap. Hold near ground and crank it. No spark...... replace coil. Spark.... connect to dizzy cap and check for spark at one of the plug wires. Quote Link to comment
metalmonkey47 Posted October 15, 2011 Author Report Share Posted October 15, 2011 MM your pictures look correct. If you have spark at the points then you should be gettin a high volt spark from the coil wire to the dizzy cap. Hold near ground and crank it. No spark...... replace coil. Spark.... connect to dizzy cap and check for spark at one of the plug wires. Very weak spark coming from the coil. Brand new coil, so I'm guessing it's coincidence that its not firing. Gonna swap on the spare and start it. Wish me luck Quote Link to comment
metalmonkey47 Posted October 15, 2011 Author Report Share Posted October 15, 2011 (edited) Nope, still no start. Tried on two coils. 12V on both sides of coil with IGN on. According to the wiring diagram, NOT correct. One is supposed to ground with condenser?? So how do I have 12V on the negative??? EDIT: I unhooked the - post on the coil and reads 13.3V @ the negative terminal. Edited October 15, 2011 by metalmonkey47 Quote Link to comment
datzenmike Posted October 15, 2011 Report Share Posted October 15, 2011 If the motor just happens to stop with the points open you will read 12 volts on the neg coil terminal. If points are closed it will be much closer to ground. Run a good ground wire from the head or block to the dizzy body. The points ground when closed and draw power through the coil to 'charge' it up. If the dizzy has a poor ground to the block there will be problems. Quote Link to comment
metalmonkey47 Posted October 15, 2011 Author Report Share Posted October 15, 2011 (edited) Ran a 8 gauge ground from dizzy base to intake manifold. No difference. Gonna clean the main ground up anyways though. Weird problem. EDIT: Nope still doesn't run. Not even a single fart out the exhaust. Edited October 15, 2011 by metalmonkey47 Quote Link to comment
metalmonkey47 Posted October 15, 2011 Author Report Share Posted October 15, 2011 Checked for spark @ plugs, and it's weak. It will cough,but refuses to fire. Spark is weak and intermittent. Quote Link to comment
datzenmike Posted October 15, 2011 Report Share Posted October 15, 2011 1/ Run a 12v jumper from the battery to the coil positive. (this eliminates the ignition key and all the wiring to it) If you get hotter fatter spark then you aren't getting full voltage from the key. 2/ Run a ground wire jumper to the coil negative side and touch it on and off several times with the key ON. Check the spark directly from the coil wire that goes to the dizzy cap. (this eliminates the dizzy and points) If you get a hot fatter spark then the points or something in the dizzy is at fault. Quote Link to comment
metalmonkey47 Posted October 15, 2011 Author Report Share Posted October 15, 2011 (edited) Whelp, I think I've found the problem. I pulled the ballast resistor connections to clean em, and the damn thing fell to pieces. And it looks like this: Do I need any specific resistance to replace? Will my .8ohm be sufficient? 1/ Run a 12v jumper from the battery to the coil positive. (this eliminates the ignition key and all the wiring to it) If you get hotter fatter spark then you aren't getting full voltage from the key. 2/ Run a ground wire jumper to the coil negative side and touch it on and off several times with the key ON. Check the spark directly from the coil wire that goes to the dizzy cap. (this eliminates the dizzy and points) If you get a hot fatter spark then the points or something in the dizzy is at fault. I'll double check after the above is repaired Edited October 15, 2011 by metalmonkey47 Quote Link to comment
datzenmike Posted October 15, 2011 Report Share Posted October 15, 2011 The resistor only comes into play when motor running with the starter off. When cranking with the key in start the ballast resistor is by passed and a full 12v is applied to the coil via the Black/Red wire... well unless the connection on the other terminal is as bad as that one. Quote Link to comment
Laecaon Posted October 15, 2011 Report Share Posted October 15, 2011 Where does the White/Black go off of the coil? It should splice in with the Black/Red (also your Black/Blue), but that could be in the harness somewhere. It just kinda looks like it goes nowhere... It kinda looks like there is a damaged wire coming out of the plug Black/Blue at the ballast resistor. Is it damaged? What is it connected to? I think it should be connected to the White/Black. And the resistor is used all times, except at start. It is important to not burn up your points. Quote Link to comment
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