Rough Running When Hot |
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scoutpilot
Member Joined: 30 Dec. 2008 Location: Asheboro, NC Status: Offline Points: 4373 |
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Yeah. Lazy Saturday afternoons. Grab the wife and fly off to a place relatively close with a decent restaurant. Fly home in the evening, or the next morning.
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Dark Horse
Member Joined: 29 May 2013 Location: Alabama Status: Offline Points: 49 |
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Yep, those are great times.
OK, I've had time to go over your suggested procedure, and think I follow everything. I really have only one question before I get started, and it would probably be obvious if I could walk out the door and simply take a look, but since the Jeep is 30 minutes away and there are no parts houses anywhere near the farm I need to go prepared for everything when I head down there. So, with that in mind, where is the best place to attach the (borrowed) vacuum gauge, and what thread size will it be? I'm guessing mine has the vacuum port in the manifold for the wipers (it no longer has wipers, but did at one time), probably with a plug in it now. Do you happen to know the thread size of that port in case I need to take a hose-barb fitting with me to adapt to the gauge? I'm guessing it's 1/4 NPT, but possibly 1/8? Or is there a better option? Thanks
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scoutpilot
Member Joined: 30 Dec. 2008 Location: Asheboro, NC Status: Offline Points: 4373 |
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That port is the best location. Off the top of my head I don't recall that size. I'll get it for you though, a little later this AM.
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Dark Horse
Member Joined: 29 May 2013 Location: Alabama Status: Offline Points: 49 |
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Scout,
I was able to get a dwell/tach and a vacuum gauge today and play with the engine a bit this morning. The gauge had a set of adaptors that included the right fitting for the manifold. Starting with the timing set as described in the book (.020 gap, flywheel IGN mark centered in the window, and rotate the distributor until the points just pass a .0015 feeler gauge with some drag), and the idle mixture screw set at the suggested starting point, I hooked up the gauge and tach after getting the engine up to operating temp. I was showing 19-20 in. on the gauge at idle, and the tach was showing 500 (but this was on an 8 cyl scale, so...1000?). Rotating the distributor CLOCKWISE "audibly" increased the rpm as well as the vacuum reading, COUNTERCLOCKWISE caused both to decrease. However, the tach wasn't responding right, and there was very little change in the reading even over wide swings in the rpm as heard by ear. So, I rotated the distributor clockwise until I got a max reading of about 21 on the vac gauge, then rolled it back until I got an approximate drop in rpm of around 100 (by ear) and a vac reading of about 20. Moving to Step 3 in your instructions, I tried backing off the idle stop screw to get a "best" vac reading, but any setting below having it screwed all the way in resulted in a stumbling idle that tried to drop below a speed that would allow it to continue running. I turned my attention to the idle mixture screw and adjusted it to get the best, smoothest idle, which was 1/2 turn OUT from the "book" setting. After this I was able to back the idle stop screw out just a little bit (maybe 1/2-1 turn) to get a bit lower idle, but I don't think it's quite down to 700. I'm guessing it's just a little under 800, going by ear (sure wish that tach had been working right). I drove it around a long time and it ran fine. Temp never quite got to 180, mostly stayed around 170-175( OAT today was b/t 70-80F). I still have the odd time where it will be idling fine, then after manipulating the linkage it will try to drop below the normal idle setting. A blip or two of the accelerator will usually clear it up and it will return to a smooth idle. However, during the last 30 minutes or so of driving it, I never was able to get that to happen again, so maybe it isn't doing it anymore. I did spray ether over all the usual suspects for vacuum leaks, but did not detect any change in rpms. Dumb question time: Do the dwell/tachometers need to be specific for 6 volt systems? I didn't think they did, but I don't understand why the one I had didn't respond predictably (unless it is defective). Dumb question #2: Rotating the distributor CLOCKWISE is INCREASING or DECREASING the timing? I could pull the cap and rotor, rotate the distributor and watch the points and figure it out, but after I had it set where I thought it should be I didn't want to mess with it. Oh, yeah - as a little "bonus" for my efforts today, I discovered I have a leaking rear main seal. Joy! Thanks
Edited by Dark Horse - 25 Nov. 2014 at 12:27am |
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scoutpilot
Member Joined: 30 Dec. 2008 Location: Asheboro, NC Status: Offline Points: 4373 |
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To answer the question first. Clockwise advances timing. CCW retards it. The tach should be marked or it will be in the instructions as to the correct voltage. Without a 4 cylinder band you do have to double the 8 cylinder readings. You've made progress today. Get a proper tach hooked up, check it again. Then take it for a ride.
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Dark Horse
Member Joined: 29 May 2013 Location: Alabama Status: Offline Points: 49 |
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So, to clarify - the dwell/tach DOES have to be compatible with a 6V system? The one I borrowed has no instructions with it anymore, so I have no way of knowing if it is. The other thing I noted was that the dwell setting was showing only 19 deg. Even doubled, that would only be 38...
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scoutpilot
Member Joined: 30 Dec. 2008 Location: Asheboro, NC Status: Offline Points: 4373 |
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Yes it must be compatible. There is a way around this however.
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Dark Horse
Member Joined: 29 May 2013 Location: Alabama Status: Offline Points: 49 |
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Don't you just think that because the meter is at least incompatible with the system, or possibly even defective, the dwell reading is just as unreliable as the tach?
I'm going to try and find/purchase a dwell/tach for 6V with a 4cyl scale. I'm not sure where to look, because a quick Google search before didn't reveal any that were marketed as such. When I can get one, I'll try it again. Thanks
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scoutpilot
Member Joined: 30 Dec. 2008 Location: Asheboro, NC Status: Offline Points: 4373 |
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I have been trying for years to locate one. If you set it up as I just described, you may be pleasantly surprised.
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Dark Horse
Member Joined: 29 May 2013 Location: Alabama Status: Offline Points: 49 |
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That's what I was afraid of. I guess I'll have to give that workaround method a try, then. The problem is, it makes no sense. "Power wires" and "Sensor wires"? The one I have has one black and one red wire, that's all. The + goes to the distributor terminal (where + coil wire connects) and the - goes to a ground on the engine. I don't see any way to hook it up as described with the 12V source - not enough wires to do it?
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plowpusher
Member Joined: 20 Oct. 2008 Location: lino lakes mn Status: Offline Points: 581 |
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I have a tach that reads off the secondary (plug wires) with an inductive pickup made by Snap-on
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when i grow up i wanna be a kid
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WeeWilly
Member Sponsor Member x 2 Joined: 07 May 2009 Location: Clayton IN Status: Offline Points: 3423 |
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I found an "All American dwell/tach model 549 that is for 6 and 12 volt systems on ebay. You might find one on there. Jim |
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47 CJ2A (Ranch Hand) 48 CJ2A, 48 Willys truck, T3C 3782, M274 (Military Mule)
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67charger
Member Joined: 27 Sep. 2011 Location: Kentucky Status: Offline Points: 1272 |
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Couldn't you mark a spot on the timing chain and pully and use a timing light? If your timing light is jumping around you.have a problem if its pretty much consistent on the mark your gap is probably good. I understand point gap can change spark power but if you have enough vacuum at idle I'm pretty sure your gap is right. Have check the weights or vacuum advance for proper advancement? Is your coil new or could it be heating up?
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Dark Horse
Member Joined: 29 May 2013 Location: Alabama Status: Offline Points: 49 |
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I think the main problem was the loose distributor hold-down clamp bolt I already mentioned. The Jeep is running pretty well now, so all I'm really trying to do is fine-tune it. I went through the mechanical advance and flyweights last year and got all that working properly. I was suspicious of the coil when I started this thread, but I think it was the loose distributor bolt. WeeWilly - Thanks! That's useful info. I'll keep my eye out for one. Plowpusher - not familiar with that type, but I'll look into it. Thanks, everyone
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