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| timing drift https://slantsix.org/forum/viewtopic.php?t=51946 |
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| Author: | '67 Dart 270 [ Fri May 03, 2013 4:18 pm ] |
| Post subject: | timing drift |
How much does timing drift due to chain stretch, nylon gear wear or other distributor related wear? My engine was recently rebuilt, has about 3000 miles on it, and I made the effort to have a double timing chain in it to avoid jumps/stretch issues. My distributor moved once, little hold down bolts came loose (splurged for that nifty slant six distributor wrench) but other than that, what is the expected, if any, drift due to wear on the system? My timing is suddenly a bit retarded. Of course I'll check those little bolts again, but assuming that's not it... thanks all. BG |
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| Author: | DusterIdiot [ Fri May 03, 2013 4:32 pm ] |
| Post subject: | Depends... |
Drift depends on how bad, how old, and how abused... I've had single stock timing chains go as far as +/- 8 degrees doing the static roll the engine back and forth test (love those old big blocks). Points are a bit more tolerant on drift and you might be able to get away with +/- 5 degrees before noticing something was up...EI is different, they will let you know when things are salty since they have a tight pickup window and if it skips it will let you know. If your timing chain is new then that should not be the problem, it will be the distributor (and possibly the weights and springs are all crudded up with petrified grease making them stick one way then not the other). The worst case scenario would be the engine builder degreed the cam in and had to drill the gear for a bushing to make it right, and the cam bolt was a little loose and let the gear 'walk' and the bushing fell out (been there had that happen before!). -D.Idiot |
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| Author: | '67 Dart 270 [ Fri May 03, 2013 6:24 pm ] |
| Post subject: | Thanks.. |
It had points, but I upgraded to electronic distributor. Must have moved again... Thanks so much. BG |
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| Author: | KBB_of_TMC [ Fri May 03, 2013 8:22 pm ] |
| Post subject: | |
Don't overlook the possibility that the harmonic balancer outer ring can slip with respect to the hub. |
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| Author: | '67 Dart 270 [ Sat May 04, 2013 10:58 pm ] |
| Post subject: | timing issue? |
OK, so I'm having what appears to be a timing issue. I say this because I've changed out all the electrical items save the distributor itself (and the wiring harness but I've considered that more than once). The carbs are working perfectly, the electric chokes are working, I have good fuel pressure, all just as before to this problem. I gapped my new NGK plugs at 0.035 as I always do. My slant starts up when cold, but otherwise it is hard to start. Cranks really fast, but I have to crank for long periods and sometimes I get some "breathing" out of the carbs, like gas fumes burping out of the carbs. This suggests retarded timing to me. As you said, my harmonic balancer may have slipped, so I don't know if the reading is correct when I put the timing light to it. I have a new double timing chain, so I don't think that has stretched or slipped. When it does start, it runs beautifully, idles smoothly, has lots of power (catches second easily), vacuum advance is operating, no hesitation - and there is no stalling or pinging or any such thing. In fact, it idles so smoothly, sometimes I think it's stalled but its purring like a kitten (OK, more like a quiet sewing machine) It does restart quickly when hot, just after I shut it off, but if I wait a bit, then it's hard to start again. Just as a reference, when it's running it does so as it did prior to this problem (except it used to fire up immediately, every time, hot or cold). I suppose it could run even better, and perhaps I'm just being fooled by the durability and resiliency of the vaunted 225 slant. If the timing were way off, I would think it wouldn't run so good when it is running. I tried adjusting the distributor counter clockwise (advance, right?) but the issue remains. In fact, I'm not getting much response from any setting on the distributor adjustment slot - seems to behave similarly no matter where I turn it within the slot. This is not the same as before, that is, it used to respond differently with small changes in the distributor adjustment (as one might expect). I can try the "second" bolt on the distributor for extra adjustment, but before I do... Assuming the timing didn't really drift, could this be a bad pickup or something in the electronic distributor. Do distributors go bad this way? Would this present the symptoms I'm seeing? The coil, plugs wires, ECU, etc are all new, the system is charging normally when running, and again, when it is running, it appears to run perfectly. Just the hard start problem. I'm having a bad time with my Dart, I'm starting to think it's possessed... If anyone thinks it might be the distributor or has any ideas on what it might be, I'm open to any suggestions.... I have another distributor in the garage somewhere, I'm sure, can someone remind me of how to swap it out? I just put the new one in with the rotor shaft (button) in the same position as the old one was? I used to work on cars a lot many years ago, but I'm rusty on some stuff, and electrical is not my favorite thing. BTW, why do they use nylon gears on these distributors (more quiet?)? Do those fail often? Thanks for any help, I'm dying to drive my Dart to work again, but I can't trust it right now. BG |
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| Author: | Jerame_c [ Sun May 05, 2013 8:49 pm ] |
| Post subject: | |
my suggestions are run a ground wire to your ignition module mounting screw and possibly throw a new ballast resistor at it. if you have the dual type your starting resistor may be bad. when cold the running resistor would have a bit lower resistance helping you start. |
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| Author: | DusterIdiot [ Sun May 05, 2013 9:03 pm ] |
| Post subject: | You can check. |
The distributor lead wires, these get hard and cracked near the plug through the body ,if so they may not be triggering your module if they lose contact. FYI. -D.Idiot |
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| Author: | '67 Dart 270 [ Sun May 05, 2013 9:14 pm ] |
| Post subject: | distributor lead wires... |
OK, so I have a single ballast resistor changed that out already. Funny thing is a couple times when cranking for a period, it seemed to start just when I let go of the key, as if there were some contact issue....but I changed to a new ignition switch, still the problem persists. So, the distributor lead wires, do you mean the one's from the distributor to the the plug for from the plug that mates with the distributor to wherever those go? Thanks, I'm really thinking it is ignition circuit failing, not timing. I wish I had one of you guys at my house for an hour or two... bg |
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| Author: | DusterIdiot [ Sun May 05, 2013 9:19 pm ] |
| Post subject: | Ok... |
Quote: Funny thing is a couple times when cranking for a period, it seemed to start just when I let go of the key, as if there were some contact issue....but I changed to a new ignition switch, still the problem persists.
That's the transition from the start to the run circuit, I had a car with that problem, ended up being an issue at the bulkhead connector (corroded connections). You might need to pull up your wiring schematic and see which bulkhead plug has the lead for your ignition and clean it up.-D.Idiot |
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| Author: | '67 Dart 270 [ Mon May 06, 2013 10:16 am ] |
| Post subject: | Ok... |
Now we're getting somewhere. I'll add that this whole thing started with an ECU going out, could be the bad connection caused the problem? I'll see what I can find, thanks so much. bg |
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| Author: | '67 Dart 270 [ Mon May 06, 2013 10:19 am ] |
| Post subject: | service manual |
Taking the board's advice, I have the official '67 service manual, might it be in there? bg |
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| Author: | 64ragtop [ Mon May 06, 2013 8:40 pm ] |
| Post subject: | |
The BEST rundown on this I've seen |
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| Author: | Jerame_c [ Mon May 06, 2013 11:30 pm ] |
| Post subject: | |
Quote: Funny thing is a couple times when cranking for a period, it seemed to start just when I let go of the key, as if there were some contact issue....but I changed to a new ignition switch, still the problem persists.
I have had this exact problem twice. on my 78 truck and on my 73 duster.The truck I was able to fix with the ground jumper, but that was after I had thrown 3 ecu's at it. In the duster I completely rewired my engine when setting up the fuel injection. Clean all your contacts and check to see how stiff the wires are close to the crimps. if they are really stiff or brittle feeling for the first half inch then your wire has corroded inside and will need replaced. |
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