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Discussion Topic:
Engine miss
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budee |
08-27-2019 @ 10:20 AM
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Member
Posts: 3
Joined: Aug 2019
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I have 46 F0rd and the engine has a miss that I can find out why, Have replaced spark plugs and new spark plug wires , new distributor cap rotor had new points installed , carb rebuilt , the car starts right up runs well when at a idle , but when you speed up the engine it starts to miss , I sure could use some help, the points were set on a machine. Thanks for any Help SID
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Mr Rogers |
08-27-2019 @ 1:13 PM
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New Member
Posts: 106
Joined: Jul 2019
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Run your engine at a higher RPM until it begins to miss ...... in the dark. See if you can see a spark within the wiring or distributor area. A shot in the dark so to speak!!
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37RAGTOPMAN |
08-27-2019 @ 2:12 PM
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Senior
Posts: 1969
Joined: Oct 2009
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hi did it miss before ? tuneup what was the compression,? if you have insulated pliers, try removing one spark plug wire one at a time, also in the dark try misting water on the spark plug wires and see if you see the spark jump hope this helps 37Ragtopman
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budee |
08-28-2019 @ 4:51 AM
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Member
Posts: 3
Joined: Aug 2019
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Thanks for the reply, yes it did miss before I changed the items as for mentioned, will look and see if any spark around plugs and distributor, what about the vacuum advance can it cause the miss?, if so how do you adjust? Thanks again, SID
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37RAGTOPMAN |
08-28-2019 @ 7:00 AM
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Senior
Posts: 1969
Joined: Oct 2009
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take a compression test FIRST,,,, before you do any ELSE, see what it is, you can do a leak down test, to see EXACTLY what the problem is, you might have a burnt valve, or stuck valve if the engine was sitting for a while. you might have to use a oil mist down though the carb with engine running, MARVEL MYSTERY OIL is good to use, do this outside because it will smoke, you even add MMO to the gas, and drive the car for a few miles to see if the miss goes away hope this helps 37Ragtopman
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JayChicago |
08-28-2019 @ 6:04 PM
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Member
Posts: 492
Joined: Jan 2016
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My 40 came to me with an intermittent miss at speed. Never felt it at idle. I finally added MM oil to the gas tank and the miss disappeared immediately! It was a sticking valve. I’m still amazed that a few ounces of MM was able to eliminate that problem.
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budee |
08-29-2019 @ 4:57 AM
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Member
Posts: 3
Joined: Aug 2019
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I will try some MM and see what happens. Thanks-----SID
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supereal |
08-29-2019 @ 12:45 PM
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Senior
Posts: 6819
Joined: Oct 2009
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Check with a vacuum gauge. If you see the needle flutter, it usually indicates a valve problem such as sticking valve stems from deposits. If you see a fluctuation between 3 to 5 inches that returns to normal, about 25 inches, that will confirm it, A fast needle vibration between 14 and19 is usually from worn valve guides. It can also be due to one or more weak valve springs. Give the amount of changing done, an ignition problem doesn't see likely.
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1935fordtn |
08-30-2019 @ 12:59 PM
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Member
Posts: 31
Joined: Feb 2015
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Have you checked the overall ignition Dwell?? To low of Dwell can cause this issue, and sometimes even excessive can. Also what brand of points did you use? A worn breaker plate pivot, or low quality points with not enough spring tension and cause point bounce at higher rpms casusing a miss.
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