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Discussion Topic:
New Miss
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TomO |
04-15-2016 @ 8:14 AM
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Senior
Posts: 7244
Joined: Oct 2009
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Randy, Your spark looks weak in the video that you Emailed me. First check the spark plugs for the correct gap of .025" and clean plugs Next check the Primary circuit resistance by connecting a voltmeter COM lead to the NEG post of the battery and the POS lead to the Battery or - lead of the coil. Remove the distributor cap and bump the starter until the points are closed. Turn on the ignition switch and read the meter. It should read 0.2 Volts or less. Turn the ignition switch on and off several times. The meter reading should be the same every time if the switch is good. Move the leads to check the primary resistance from the coil to the points. The COM lead on the DIST or + terminal of te coil and the POS lead on the points. The reading should be 0.1 or lower. If any reading is out of specs, move the POS lead to isolate the problem. I would use a dwell meter to check the dwell at idle and at all rpms up to 2,00 rpm. The dwell should be set at 26 degrees and not vary more than 2 degrees as the rpm is increased. Next test the distributor ground circuit by connecting the com lead of the ohmmeter to the DIST terminal of the coil and the POS lead to a good engine ground. The meter should read a short. Move the point plate to advance the spark and watch the meter, If the meter flickers, check the wire going to the points and the grounding wire inside the distributor. Check that the condenser is firmly mounted to the the point plate. If it can be moved in any direction, it will not have a goof ground. Check the rotor and cap for corrosion or burnt contacts. I would also do a cylinder balance test by removing one plug wire at a time and notice if the engine slows the same amount for each plug. I any one or more plugs do not slow the engine the same as the others, replace the plug and check the wire.
Tom
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TomO |
04-10-2016 @ 7:49 AM
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Senior
Posts: 7244
Joined: Oct 2009
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Randy, the ignition switch and lock cylinder are 2 different parts. You can replace the ignition switch and keep your lock cylinder. I don't think your problem is the switch. I would like you to try the test again with a reduced spark gap on the tester. Reduce the gap by a couple of turns and retry the test. I have sent you a PM
Tom
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RAND |
04-09-2016 @ 3:50 PM
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Member
Posts: 56
Joined: Sep 2012
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Somebody please delete those video attachments I can email it...but cant get it to work here Thank you, Randy
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RAND |
04-09-2016 @ 3:39 PM
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Member
Posts: 56
Joined: Sep 2012
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try again video
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RAND |
04-09-2016 @ 3:13 PM
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Member
Posts: 56
Joined: Sep 2012
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Today I was finally able to hook up the spark tester that you suggested...very light blue spark at idle. and a diffident miss with the engine reved up. See video I attached...if it works. I'm thinking that it might be the ignition switch? Key can wiggle a bit in the switch too! Any idea how to remove the ignition switch? and where I can get a new one? I'm disappointed that I wont be able to use my original keys any more =/ I'll keep you posted.... Tkx for your help, Randy
This message was edited by RAND on 4-9-16 @ 3:16 PM
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RAND |
04-05-2016 @ 8:06 PM
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Member
Posts: 56
Joined: Sep 2012
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Got the tester but haven't had any time in the garage yet...Randy
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RAND |
03-28-2016 @ 6:42 PM
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Member
Posts: 56
Joined: Sep 2012
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Thanks Tom... Looks like Im gonna get one of those testers from Napa and report back. Thanks again! Randy
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TomO |
03-28-2016 @ 7:50 AM
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Senior
Posts: 7244
Joined: Oct 2009
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Your answers to my questions in the previous post suggest that the problem is more likely a spark condition than a fuel starvation issue. I did not mean for you to take the top off of the carburetor when the engine is running, just to take it off after it has idled for a few minutes to fill up the float bowl. One way that I check for ignition problems is to use a spark tester like the NAPA SER 606. http://www.napaonline.com/napa/en/p/SER606 I set it to 20 and connect it to one plug and start the engine. I should see a constant blue spark at idle. If the spark is red, orange or intermittent, I start looking for a cause. Red or orange spark is usually due to a weak coil, weak condenser or low voltage going to the coil. It can also be caused by incorrect dwell. Missing spark can be caused by a bad ignition switch, poor connection at switch, coil or points, a wire that is broken inside the insulation (usually occurs near the connection, A firm tug will usually show this up), poor grounding of the points or condenser (the condenser or points should not move when you try to move them) or a bare wire grounding out occasionally.
Tom
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RAND |
03-27-2016 @ 7:09 PM
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Member
Posts: 56
Joined: Sep 2012
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Sorry for taking so long to get back on this. Busy doing life. Did the symptoms appear or get worse after the carb was rebuilt? (ran fine for awhile after new carb was installed) Does it get worse turning and when you accelerate hard? (no..Same) Does the engine respond normally when you accelerate when standing still? (No. seems to get worse as it warms up) Your float level could be set wrong if the answer to these questions is yes. Run the car at idle and check the fuel level in the carb by removing the top. If it is near the correct level, lower it about 1/16". If it is low, raise it about 1/16". (sorry but I'm not comfortable taking the top off) If the answer is no, check the wire to the ignition switch for any bare spots or a loose connection. check for loose connections inside the distributor or a poor ground on the condenser. ( I did look for loose wire and bad ground, but cant fugue out how to check wire under the plate? I do have the dizzy out of the car to send out to Bubba, But first I think that I need to check the ignition switch first. Merc was rewired in 1981 by my Dad so I don't think that there is any bare wires. Maybe loose? Tracker... mentioned he had the same symptoms and it ended up being the wire in the dizzy. but his got worse and completely died. Mine has never died. Randy
This message was edited by RAND on 3-27-16 @ 7:14 PM
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TomO |
03-07-2016 @ 4:37 PM
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Senior
Posts: 7244
Joined: Oct 2009
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Randy, I do not know the pros and cons of switching distributors. The only one that I knew of converted back to the original distributor as his problem was elsewhere and he did not see any performance improvements. Did you see my previous post? If you answer those questions, maybe I can give you direction on how to determine wher that problem is.
Tom
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