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| Engine stutters intermittently at idle and deceleration https://slantsix.org/forum/viewtopic.php?t=43046 |
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| Author: | Josh P [ Wed Dec 29, 2010 4:49 pm ] |
| Post subject: | Engine stutters intermittently at idle and deceleration |
My '66 Dart has a slight, and intermittent, miss/stutter/stumble while idling and during deceleration. I haven't noticed much different when the engine is cold vs nice and hot, however there seems to be a middle ground (warm, but not fully warmed up) where the issue isn't present (at least not at idle). I read a post today about checking the rotor-to-cap phasing by drilling a viewing hole in an old dizzy cap and hooking up a timing light. I didn't notice any difference between 600RPM and ~2500RPM. Not sure if I was doing it wrong but if anybody knows of any thing I'm missing, I'm all ears. One thing I did notice while doing the test is that the contacts on my cap were worn oddly. The leading edge of the contacts looked as though there was some arching. The trailing edge of the contact was well defined, yet the leading edge was distorted (can't think of a better word to define it). So I'm wondering, did I not see any difference in my test because the rotor was not yet in front of the viewing hole at 600RPM, and moved further from the hole at higher RPM? If this is the case I take it, I should replace the cap and rotor and make a few adjustments? Also, if I do need to make adjustments to the bolt that holds the housing to the shaft, how do I get to it without removing the dizzy? |
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| Author: | carlherrnstein [ Thu Dec 30, 2010 8:00 am ] |
| Post subject: | |
I would bet that if you do a compleat tune up it would clear up. Points/condenser, cap, rotor, plugs, perhaps plug wires depending on how bad the are, and make sure the choke is working properly and if that still doesn't cure it then adjust the valves. Hope this helps |
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| Author: | Josh P [ Thu Dec 30, 2010 10:23 am ] |
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[quote="carlherrnstein"]I would bet that if you do a compleat tune up it would clear up. Points/condenser, cap, rotor, plugs, perhaps plug wires depending on how bad the are, and make sure the choke is working properly and if that still doesn't cure it then adjust the valves./quote] Plugs are only a few months old, same with cap and rotor. Just got new magnecor wires last week. And I have electronic ignition (orange box). The choke is working perfectly, and I adjusted the valve lash just three weeks ago. I've also checked the timing, idle mixture, idle speed, etc. I'm fairly confident that this is also not a vacuum leak. Thinking it has something to do with the ignition system (EI conversion by previous owner) or my BBS that is on its last leg. I'd like to know if anyone has a trick for getting at the adjustment bolt that holds the distributor housing to the shaft. My best guess is to remove the oil filter (one with a anti drain-back valve). My WIX filter does have an anti drain-back valve, but how much oil will still come out? If I can loose less than a pint then I may just try that. |
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| Author: | THOR [ Thu Dec 30, 2010 11:03 am ] |
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You can fashion yourself a fancy tool (Doc has a picture up somewhere of said tool) which is basically the box end of a wrench with a 90 degree bend about 2" inboard of the box. This allows you to sneak in next the the filter and loosen the bolt. The only other option without removing the dizzy is to remove the filter. If you are quick you wont lose much oil. The filter only holds 1/2 quart anyway. ~RDE~ |
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| Author: | Doc [ Thu Dec 30, 2010 11:09 am ] |
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| Author: | 4speed [ Thu Dec 30, 2010 11:11 am ] |
| Post subject: | |
How many miles on the engine? The BBS is a good carb-If you think the shaft is worn out you can pack some very thick grease around the shaft at both ends to see if this takes care of the problem temporarily. And you can send out the throttle plate part of the carb and have it sleeved. |
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| Author: | Josh P [ Fri Dec 31, 2010 1:27 am ] |
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Quote: How many miles on the engine? The BBS is a good carb-If you think the shaft is worn out you can pack some very thick grease around the shaft at both ends to see if this takes care of the problem temporarily. And you can send out the throttle plate part of the carb and have it sleeved.
The previous owner stripped a bunch of the threads including the fuel inlet, and several of the bolts that hold the carb together. So some things are JB welded together others have been re-tapped for larger bolts, and I'm not interested in keeping it much longer.Doc, I like your sneaky tool. I tried using one of those ratcheting box-wrenches with the swivel ends, but it wouldn't fit on the bolt. So I faced my fears and pulled the distributor out (not as scary as I thought). So after playing with both adjustment bolt on the bottom of the distributor and testing with the shaft 1 tooth retarded as well as advanced, it seems to run best (read: smoothest, with no miss/stutter) with the shaft advanced 1 tooth from where I started (timing mark read something like 27°, shockingly no noticeable ping, at least at idle). It nearly dies if I set it 1 tooth retarded from the initial. So I put it back to where it was before starting my adventure out of fear of the timing mark at 27°. How far is the dampener likely to slip anyway, could 27° be closer to 5-10° or would it be at most something around 20-25°? Also, a side question about finding TDC. I've tried bumping over the engine using the pull-the-fan/belt but the belt slips (it does have the correct deflection), and the fan is really hard to spin (it is an aftermarket fan with flexible blades curtsy the previous owner). Should I be alarmed it isn't easier to turn and does anybody have other suggestions for turning the motor? |
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| Author: | Aggressive Ted [ Fri Dec 31, 2010 9:11 am ] |
| Post subject: | |
Josh, I bought a bolt to put in the crank and use that and a socket and a long handled ratchet wrench. That makes it much easier. Don't slice your wrist on that fan blade! On the miss, I went through something similar on my new rebuild. Make sure your coil is seeing good voltage at least 6 volts at idle. After rewiring my engine one wire at a time with stock end connectors and a little larger wire. Changing coils to a 3 ohm and removing the resistor my coil sees 12 volts at a minimum. No miss any where in the rpm range from 600 to 4500 rpm. Click on the red link below my name for pictures. It is a 3 ohm HEI coil and does not require a resistor. Still running the orange box. It will idle for hours in rush hour traffic and never miss a beat. NGK plugs gaped at .045. Good luck! |
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