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heinz57
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Jun 17, 2011, 3:28 PM
Post #1 of 10
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81 ford f350 Engine miss
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81 Ford 4.9 6 just replaced head gasket. I can pull plug wires on first 2 cylinders, one at a time, and has no affect on idle. Changed plugs and getting good spark thru wires. but apparently no detonation in cylinders. Double checked my valve adjustments before putting on cover and they checked to Chilton's specs. Distributor is new. Suggestions on what to check now.
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Hammer Time
Ultimate Carjunky
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Jun 17, 2011, 3:31 PM
Post #2 of 10
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Re: 81 ford f350 Engine miss
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Do a full compression test and check it carefully for any vacuum leaks
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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heinz57
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Jun 17, 2011, 4:05 PM
Post #3 of 10
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Re: 81 ford f350 Engine miss
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Did compression check after head was installed, 120 all cylinders. Checked for vac leaks and cannot find one.
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Hammer Time
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Jun 17, 2011, 4:09 PM
Post #4 of 10
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Re: 81 ford f350 Engine miss
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Apparently your tests were faulty assuming your firing order is OK.
You need to verify spark and compression on those cylinders. It's a carbureted engine so a vacuum leak is the only thing that will rob fuel.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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heinz57
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Jun 17, 2011, 4:40 PM
Post #5 of 10
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Re: 81 ford f350 Engine miss
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Have run 10 or more compresion checks on this engine so I'am convinced the last 2, ran it twice, are right. I can hear and see spark getting to the cylinders. Will check again for vac leaks. Thanks
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heinz57
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Jun 20, 2011, 4:15 PM
Post #6 of 10
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Re: 81 ford f350 Engine miss
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Been racking my brain to see if I can think of anything that would affect #1 & #2. It's been over a month since I tore this engine down and I just remembered that when pulling the push rods I knocked over the box I was using to keep them in order and scrambled the push rods for these two cylinders. Is this where I could have screwed up? Are the exhaust and intake diff lengths?
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Hammer Time
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Jun 20, 2011, 4:20 PM
Post #7 of 10
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Re: 81 ford f350 Engine miss
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Very possible. I don't remember if they were different but I can tell you that a properly done compression test would show that. The result of wrong pushrods would be loss of compression.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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heinz57
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Jun 21, 2011, 2:41 PM
Post #8 of 10
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Re: 81 ford f350 Engine miss
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Checked all connections and replaced all vacuum lines that were questionable. Rechecked torque settings on #1 & #2 and ran compression test on those two, both were 122. Checked push rods and all were the same length. At a loss, anything else I can do, check? I appreciate your help.
(This post was edited by heinz57 on Jun 21, 2011, 2:42 PM)
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heinz57
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Jul 6, 2011, 10:07 AM
Post #9 of 10
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Re: 81 ford f350 Engine miss
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Still haven't got this one figured out but today I noticed small air bubbles coming out around the #1 cylinder head bolt where some oil had accumlated. Compression tested this cylinder at 122 after retorqueing head bolts. Is this a symptom of a crack in the head?
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Hammer Time
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Jul 6, 2011, 12:08 PM
Post #10 of 10
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Re: 81 ford f350 Engine miss
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Yes, sounds like it might be a cracked head. The crack will open up as the head gets hotter.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
(This post was edited by Hammer Time on Jul 6, 2011, 12:08 PM)
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