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| Mistery miss...Looks like a timing chain is in my future. https://www.slantsix.org/forum/viewtopic.php?t=24807 |
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| Author: | Eric W [ Wed Sep 05, 2007 11:19 pm ] |
| Post subject: | Mistery miss...Looks like a timing chain is in my future. |
Over the course of a few months, the Satellite has developed a miss, or should I say a pfft pfft pfft out the exhaust pipe. Here is what I've done so far: Replaced distributer with a distributer I had around. Nice, tight bushings, recurved like the one I replaced. Installed new cap and rotor (extended tip like Dan recommended) and use Accell 8mm wires with Blaster II coil. NGK plugs. Went through carburetor again, #58 jet. Did a compression check, 135 to 145 across cylinders. So there goes burnt valve theory (valves set to stock .010/.020"). Timing set at 8* BTDC. Now, tonite I checked the timing again and noticed the mark bouncing around about 2.5* +/- 0 on timing mark (dial back light set to 8* so mark is pointing to 0). The engine runs fine cool or warming up, but the irregular exhaust starts after it reaches operating temp. It also pulls nice and I drive 65-70 on the way to work 40 miles each way. I replace the ECU with a known good one, and still same thing at idle. Could the pick up in the distributer be on its way out? I also tried a different coil (stock electronic unit) and my old 7.5mm plug wires with no change. Any thoughts? |
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| Author: | Todd360 [ Thu Sep 06, 2007 3:26 am ] |
| Post subject: | |
Just a thought...what kind of vacuum is it pulling at idle? Could be a vacuum leak???? Todd |
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| Author: | itlldo1 [ Thu Sep 06, 2007 3:33 am ] |
| Post subject: | |
If your timing mark is walking with the vacuum disconnected at the carb, I'd check the mechanical advance springs in the distributer. If they're ok I'd look to the timing chain / gears. I had the same problem with the /6 in my '78 D100. I had over 10 deg of play in the timing chaing-replaced the chain and gears-problem solved. Mike |
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| Author: | Eric W [ Thu Sep 06, 2007 8:25 am ] |
| Post subject: | |
Quote: Just a thought...what kind of vacuum is it pulling at idle? Could be a vacuum leak????
It pulls 17 inches at idle.
Todd |
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| Author: | argentina-slantsixer [ Thu Sep 06, 2007 8:27 am ] |
| Post subject: | |
valve lash |
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| Author: | Bren67Cuda904 [ Thu Sep 06, 2007 8:45 am ] |
| Post subject: | Re: Mistery miss... |
Quote: (valves set to stock .010/.020").
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| Author: | argentina-slantsixer [ Thu Sep 06, 2007 9:25 am ] |
| Post subject: | Re: Mistery miss... |
Quote: Quote: (valves set to stock .010/.020"). |
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| Author: | SlantSixDan [ Thu Sep 06, 2007 9:51 am ] |
| Post subject: | |
Listen to the exhaust at idle. Is the misfire rhythmic & regular, or is it random? |
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| Author: | oldgoat83 [ Thu Sep 06, 2007 11:47 am ] |
| Post subject: | |
I'd actually like to know your ideas either way Dan. |
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| Author: | Aggressive Ted [ Thu Sep 06, 2007 6:36 pm ] |
| Post subject: | |
Sounds like you covered the bases, however...... The vacuum can can cause it to bounce around. Unplug it and see if it settles down. If it does, then unscrew the canister one turn with a 3/32 allen wrench. That may settle it down when you plug the line back in. If not, unscrew it a little more. It took 3 turns on mine. Does your exhaust pipe or muffler have any small pin holes in it? They can sure throw you off when your trying to listen for a steady sound. |
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| Author: | SlantSixDan [ Thu Sep 06, 2007 6:54 pm ] |
| Post subject: | |
Quote: I'd actually like to know your ideas either way Dan.
Rhythmic miss means one or more specific cylinders are failing to fire all or most of the time. Could be a bad spark plug or plug wire to particular cylinder(s), could be a vacuum leak at that cylinder's intake runner...that kind of thing.Random miss means something's happening that can affect any/all of the cylinders. Could be a failing coil wire or a weak coil, could be a bad rotor or cap, could be bad points (on a car so equipped) or a failing distributor pickup coil, could be a vacuum leak at the carburetor end of the intake tract, could be a clogged or maladjusted carb idle circuit...that kind of thing. |
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| Author: | Eric W [ Thu Sep 06, 2007 8:31 pm ] |
| Post subject: | |
Actually, it is random. Which leads me to believe it may be electrical. Like I said, I have already tried two sets off wires, ECU's, and coils to rule any of those components out. The lash is spot on...I tripple check to make sure, trust me. |
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| Author: | argentina-slantsixer [ Thu Sep 06, 2007 8:37 pm ] |
| Post subject: | |
timing chain? plastic sprocket on cam? have you tried a sheet of paper on the tailpipe? when it misses is kinda like the exhaust tries to "suck" the sheet? have you connected a vac gauge and watched what happens with vac reading when it misses? |
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| Author: | Aggressive Ted [ Thu Sep 06, 2007 8:42 pm ] |
| Post subject: | |
Try tightening up the carb bolts holding it on the manifold. I always check them when things aren't quite right, then go from there. |
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| Author: | hotwheelsjr [ Thu Sep 06, 2007 10:37 pm ] |
| Post subject: | |
Funny to see this topic, as I just logged in here to post about the SAME problem!! I have a '67 B-cuda with a 225 from a '74 Dart in it. I just put this motor in last weekend because I had exhausted all avenues (so I thought) with the pre-73 motor that was in the car. I have this same miss and a hesitation from a dead stop. My timing is super advanced to make it run decent and it's steady as a rock, so I don't suspect a vac leak. Here is what I was going to post (I just finished typing it to a friend and copied it so I could post it here) -- 'It has a hesitation when starting from a dead stop and it's a bear to keep running when it's not super warmed up. It has a noticable miss when it's idling. I swapped motors this past weekend with one from a '74 Dart, hoping it was a motor/head issue, but the new motor has the same exact miss. I swapped distributors, and ECUs to no avail. In order to make either of the motors run 'ok', I have to have the timing advanced by a LOT and can not time it without the vac advance hooked up -- without it hooked up, the motor runs like crap and wants to die, period. This is the same for both motors. So, the carb is my last guess...any suggestions?' As you can see -- I had the same problem on the previous motor -- swapped distributors, ECUs, wires, new plugs, etc. Same crap... What now? |
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