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| Moderated by: Greg Fletcher | Page:   1 2 |
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| Timing and ignition - maybe | Rating: 
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| Posted: 03-29-2006 03:30 am |
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21st Post |
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Esprit2 Member
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colinw59 wrote: Hi Rory I thought of that, so I checked it. With #1 at TDC and the cam sprockets lining up, the rotor is pointing to the correct contact within the distributor. Thanks Colin, This is long. Sorry if I lose you with the length. With the crank at TDC and the cam pulley timing dots properly aligned, #1 cyl is at TDC. Good. With the engine in that position... Normally the ignition fires as the rotor arm is just overlapping the terminal on the distributor... not on-center with it. That's to maximize the rotor/terminal proximity duration as the rotor sweeps by so the spark can jump over a time period at high rpm (the spark isn't instantaneous). If you have the rotor aligned straight-on with the terminal at TDC, then the ignition timing is probably actually after TDC. You want 8 - 14 degrees before TDC. With #1 at TDC, all you should be looking for is which terminal (+/_) is the rotor pointing toward (not timing). That's the #1 terminal, so make sure the #1 spark plug wire attaches there. Then install the rest of the wires in 1-3-4-2 order, counter-clockwise around the distributor as you look at the top of the cap. "IF" #1 is pointing straight up, #3 will point at the engine block, #4 straight down and #2 at the oil filter. Now turn the crank through one more revolution, stopping when the pulley hash mark aligns with whatever static timing you want, stop there. You don't have to go around two revolutions and back to approaching #1 TDC. After you have determined the #1 terminal and installed the wires properly, it's enough to just go around once. The distributor will fire each time the crank approaches TDC. For "ignition" timing purposes, it doesn't matter if it's #1 that's firing, or #4. They'll both fire with the same advance. Connect a continuity light between ground and either of the 12v terminals on the ignition coil. With the ignition on, the test light will be off or dim when the coil is charging (OEM breaker points would be closed). The light will turn on or become bright when the points open to fire the coil. Off-dim and on-bright depend upon the current rating of the test lamp and how much current it is drawing. "Off" is just a special case of "dim"... etc. With the crank's timing hashmark set to desired static timing, test light connected and the ignition "on"... Loosen the distributor clamp so you can rotate the body (apply inward hand pressure to the distributor to hold it into the housing against the spring pressure "before" loosening the clamp). Rotate the distributor back and forth a bit to find where it switches from off/dim to on/bright. If you have followed instructions, started at #1 TDC, and went to your static timing point (8 BTDC ?), then you will find the on-off point a little clockwise from your starting point. "Clockwise" as you look at the open end of the distributor body/ top of the cap... ie, turn toward the oil filter. Find the on-off point, then rotate back and forth a few times watching the light go on-off to get a feel for where the on-off point is. From the on-off point, rotate the distributor body counter-clockwise toward the engine block until the light goes off... then a bit more. Then reverse, and rotate the distributor body clock-wise back toward the oil filter until the light "just" comes on or gets bright. Stop immediately without over-shooting. If you miss it, back up and try again. When you're comfortable that you nailed it to your satisfaction, tighten the distributor clamp. Do not release the inward hand pressure upon the distributor until after the clamp is tight... or you'll be re-installing the distributor. Now the ignition is static timed. Turn the Ignition off as soon as you're done (important... don't leave it on). Disconnect continuity test light. If the light doesn't change at all when you rotate the distributor body, then something is wrong in the distributor/coil circuit. If there's voltage at the coil (+) and (-) terminals, then follow the white wire from the coil's (-) terminal to the distributor and check for voltage there. If no voltage, the wire is bad, fix it. If there is voltage at the distributor end, but the test light doesn't change (off or dim to on or bright), then there's a problem with the Pertronix unit or it's installation. Early PERTRONIX FRAILTY: When the ignition is "On", current may or may not be flowing through the coil depending upon the position of the distributor. If the distributor is in one of the four positions where the coil/spark has just fired, then the 12v to the coil-charging current is off and not flowing through the Pertronix amp. However, at all other times, coil-charging current is flowing through the Pertronix amp full time whenever the ignition is "On" and the distributor isn't turning. That puts the amp in a 100% duty cycle condition it was not designed for... originally. In that case, early Mk 1 Pertronix amps will overheat and fry fairly quickly... a few minutes. The damage is permanent and the cure is a new unit. When working on the engine/ ignition, do not turn the ignition "On" and leave it on. Switch "On", do your task, switch "Off". Later Mk II Pertronix units have a heavier duty amp that can withstand prolonged current... but it's still best not to push your luck. Also, both Pertronix units are polarity sensitive and intolerant of reversed bias. Do not apply reverse polarity for even an instant or you'll be replacing it. I guess what I'm saying is that your Pertronix unit may have died even though you "didn't do anything to it"... intentionally. SPARK CHECK: Voltage gets to the coil via two paths. One wire goes to the ballast resistor which drops nominal system voltage down to 7-8 volts. That's for normal running. A second wire coming from the terminal on the starter solenoid, bypasses the resistor and feeds 12v directly to the coil during starting. 12v for starting, 7-8v for normal running after the starter is released. Check that both circuits are working. After confirming that the coil is getting voltage, trigger it manually and watch for a spark. To trigger the coil, remove the wires from both the (+) and (-) coil terminals. Make a jumper wire to connect the (-) terminal directly to ground. Make a second jumper and connect it to the (+) terminal and have it long enough to reach the battery'e (+) terminal. Pull the high tension coil wire off the distributor cap and make sure the other end is firmly seated in the top of the coil. Pull the boot back on the free end to expose the terminal, then hold it near a good ground... like the engine block (not the carbs/ intake manifold). Grip the wire well back from the terminal to avoid a shock. Hold the coil's high tension wire near a good ground but not touching (gotta see the spark jump). Touch the free end of the (+) jumper wire to the battery's (+) terminal briefly, then lift if off. Everytime the batterry connection is broken, the coil will fire and you should see a spark jump from the coil HT wire to the ground point. If a spark jumps, the coil and high tension lead are both good. If no spark, then one or both are bad. Replace the coil HT lead with a known good one and repeat the test. Still no spark?... the coil is bad. Replace it. With a confirmed good coil and HT wire, a spark will jump every time you lift the jumper wire off the battery (+) terminal. When you get to that situation, put all the wires back in their proper places on the coil. Now, test for spark using the Pertronix to trigger the coil. Coil 12v wires installed, coil HT lead still disconnected and held near a good round, transmission in neutral, key the starter to turn the engine over. If no spark occurs, then the problem is either in the Pertronix unit, or in the small, white 12v wire from the coil's (-) terminal to the distributor/ Pertronix unit. Test for voltage at the Pertronix end of the wire. If you have primary voltage there, then the wire/ circuit is good and the problem is in the Pertronix or it's installation. No jab intended... but are you familiar with starting a carb'd engine? In this day of fuel injected engines, that's a fair question. With fuel injection you aren't supposed to do anything other than key the starter. With carbs you need to be an active participant. You won't have much success if you don't do your part. Good luck Tim Engel
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| Posted: 03-29-2006 02:58 pm |
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22nd Post |
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colinw59 Member 
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Thank you both very much John & Tim for your very thorough replies. When I initialy got the car running, I did so with the plugs gapped at 0.025". On reading John Kimbrough's article on installing his Petronix system I regapped them to .035". After this the car ran about the same. She's not fully roadworthy yet so this was based solely upon how she sounded statically. My assumption has been that power for the spark was not being generated, or being generated irratically and not that the spark circuit was incomplete. Wrong! I pulled the new plugs last night. They were carboned up (too rich a mixture I hope, as the carbs have yet to be set, or balanced). I replaced a plug at a time and cranked the engine, better. Replaced another, better still. I replaced all four plugs and she's now runnin' fine. I'm hoping that the larger gap combined with a nice coating of carbon was the root cause of the problem, that just so happened to coincide with changing the timing belt. We have a word for this in English, coincidence! This one sent me on a fools errand for many hours! I'll road test after setting & balancing the carbs and if she exhibits the lack of spark that John Kimborough experienced, I'll trying gapping the plugs to 0.035"- 0.045". Fingers crossed. Thanks again gentlemen.
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| Posted: 03-30-2006 12:03 am |
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23rd Post |
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Esprit2 Member
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colinw59 wrote: I'll trying gapping the plugs to 0.035"- 0.045" Colin, It takes a higher voltage spark to jump a larger gap. The appropriate gap for the OEM coil was 0.023" For the Pertronix Flamethrower you can go to .035". However, I'd be cautious about going further than that. If you go to far with either high voltage or large plug gaps, you may start to have issues with the spark cross-talking between the closely spaced terminals in the distributor cap. Look at late model distributors designed for high energy coils and you'll see that the caps are very large. Sometimes the size is necessary to enclose more stuff crammed inside; but more often than not the size is also a design requirement to keep the terminals far enough apart to permit the use of the really high voltages. The Lucas distributor has a tiny cap, and the terminals are very close together. A gap of 0.035" shouldn't be a problem, but I wouldn't go with more. Don't go nutz. Tim Engel
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| Posted: 03-31-2006 12:45 am |
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24th Post |
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John Kimbrough Member
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Colin, Tim is probably right. I gapped at .045 to get it running and then began working backwards. I didn't have a problem with cut out at the higher gap, but it didn't seem necessary to keep it that wide. With the stock gap I had the same problem with carbon buildup you had and when I cleaned the plugs it ran better until the carbon built up again because the "real" spark was only intermittent. I know it sounds wierd, but the spark plug with the small gap was acting as a dead short. With the gap substantially wider, the fully developed spark ingited fine. Since I got it adjusted I have had absolutely no problems. I, too thought it was all kinds of complicated things, and practically went nuts, but it was really very simple. Good luck. John.
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