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Discussion Topic:
1949 Ford - Sticky Valves?
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hootomik |
08-01-2023 @ 1:53 AM
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Member
Posts: 14
Joined: Aug 2023
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Hi, I am new to this forum, I live in the UK and have a 1949 Ford Custom sedan which I bought (restored) from the USA and have had running for a couple of years. In 2021 it was running OK to a point, but would not rev cleanly at higher revs. I replaced the points with electronic ignition but no significant improvement. Last year I had a series of problems due to dirt in the fuel; I replaced the fuel pump and stripped and cleaned the carb, then obtained a rebuilt carb - no improvement. I let the car stand outside over the Winter and made no attempt to start it. After 4 months I tried to start it but the engine was seized. I freed it with oil down the bores, and it started-up, but although we got it to idle OK it will not rev at all - lots of misfiring and backfires. My question: could the valve stems have corrosion which is causing them to stick open as the motor warms up or I attempt higher revs? I have been through all the ignition and fuel system and replaced everything but the distributor and nothing makes a difference. I am now back to points and a condenser; the distributor looks fine, the cam gear is aluminum and looks pretty new and the timing marks all line up. Any ideas or experience are most welcome! Thanks, Mike.
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marko39 |
08-01-2023 @ 5:26 AM
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Posts: 41
Joined: Sep 2016
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i would start with checking engine vacuum and doing a compression test.
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carcrazy |
08-01-2023 @ 12:35 PM
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Senior
Posts: 1653
Joined: Oct 2009
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Some of the items that can cause lack of power at higher RPMs or loads are: a failing fuel pump, contaminants in fuel system or plugged tank vent obstruction in exhaust system or air cleaner point bounce due to weak spring
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alanwoodieman |
08-01-2023 @ 3:01 PM
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Senior
Posts: 868
Joined: Oct 2009
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lousy gas is probably the culprit in your problems, In the states we use marvel mystery oil in the gas to help prevent valve stem problems also some in the engine oil. for now if it will run at all spray some of the mmo down the carb and see if this help. if you cannot get mmo some automatic trans fluid will also work, remeber it will smoke up the joint so put the car outside
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TomO |
08-01-2023 @ 5:22 PM
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Senior
Posts: 7250
Joined: Oct 2009
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Welcome to the Forum. We enjoy seeing photos of the cars. It sounds like you have a new problem or the old one has gotten worse. Start with the basics: Check your spark at idle with the engine warm. When you hold a plug wire near a head bol6t, you should have a nice blue spark about 1/2" long. If you do not have this, the problem could be either the coil or condenser. Change on or the other and retry the spark test. If you have good spark, check the compression. It should be within 5 PSI from the lowest to highest, but if you have a problem with rings or valves there will be a significant (20 pis or more) difference. If one or more cylinders are out of range, pour about 15ml into the cylinder(s) and repeat the test. If compression increases, the rings are the problem, if it stay about the same, the problem is more than likely valves burn or sticking. Come back here withe you compression readings for further guidance. Good luck and let us know how you make out.
Tom
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hootomik |
08-02-2023 @ 7:29 AM
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Posts: 14
Joined: Aug 2023
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Hi, thank you for your comments. I have just run some Redex solution through the carb (one litre of gas, 250ml of Redex) - no change. Idles OK, but as soon as you try and rev it backfires and stutters, and will not rev. Checked the spark - good and strong. In the last few weeks I have replaced the coil (high output fitted), plug leads, points, carb, fuel pump and associated pipes. I am running it off a can at the moment because I suspect that I have a separate problem of dirt in the tank. I am using low-ethanol gas (5%). I checked the compression last week: 100psi +/- 4psi across all cylinders. The car runs a twin exhaust system, and both sides seem to push out similar amounts of exhaust gas. I have had the assistance of a couple of friends who both have V8 experience, but not side-valves. We have covered all the bases we can think of, apart from stripping the engine and having a look at the valves. I am looking on this as a last resort and hoping that one of you may have an idea that would avoid it... I am not the best mechanic!
This message was edited by hootomik on 8-2-23 @ 7:31 AM
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carcrazy |
08-02-2023 @ 9:19 AM
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Senior
Posts: 1653
Joined: Oct 2009
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If the engine backfires through the carburetor, chances are good that the fuel/air mixture is too lean or the ignition timing is off.
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trjford8 |
08-02-2023 @ 9:49 AM
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Senior
Posts: 4214
Joined: Oct 2009
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I would drop the gas tank and see what you have for crud in it. It's possible that there is some in the gas line and causing the car to starve for fuel.
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mfirth |
08-03-2023 @ 5:19 AM
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Member
Posts: 207
Joined: Nov 2017
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Hi Mike, be sure to make sure the vacuum advance diaphram on the didtributer is working properly. Also, there is a wire in the distributer under the plate that the points are mounted on that can temporarely go to ground if the insulation is compromised. Causes all kinds of problems. You can probably get a diagram of the distributer on line. Just another possiblity.
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40cpe |
08-03-2023 @ 11:10 AM
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Member
Posts: 472
Joined: Jan 2010
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I believe your compression is too good to cause your symptoms. With those readings, I believe you are a long way off from tearing your engine down. I agree with mfirth above. Check the wire under the points plate in the distributor. Insulation rubs off and shorts the fire to the points or the ignitor as the plate moves when the ignition advances. You might want to disconnect the vacuum line to the distributor and see if it still has the same symptoms. It might give you some insight on distributor problems. I noticed your changed the points, but didn't mention the condenser. The condenser can also cause mis-firing. Good luck, I hope you find the problem soon.
This message was edited by 40cpe on 8-3-23 @ 11:16 AM
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