| dgmgohl | -- 06-25-2017 @ 7:51 PM |
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I have a 53 Mercury Flathead in my 1952 Mainline. When starting the car, it idles out nicely. But when rev'd up, it bogs down. Same when driving in 1st, 2nd and 3rd gear. Installed new points, condenser, rotor, coil. Re-timed. I did turn the jets out a half a turn with no response.
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| Drbrown | -- 06-25-2017 @ 8:44 PM |
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Sounds like you are driving a standard shift (Fordomatic might indicate different considerations). Recommend using a vac gauge when adjusting the idle screws. Given your engine's lack of response under load it doesn't seem the idle screw settings are the problem. Others here can better advise you re possible carb or possible vac advance problems.
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| carcrazy | -- 06-25-2017 @ 9:25 PM |
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Are you sure the ignition timing is correct? Check the spark advance with a timing light to make sure it is properly set and that the vacuum controlled spark advance system is functioning as it should. The initial timing at idle should occur when the ball on the front pulley lines up with the pointer. Maximum spark advance should be between 15 to 17 crankshaft degrees when the engine is revved up. Are you using the original carburetor and distributor on this engine? The distributor wants to get a vacuum signal from the venturi area of the original carburetor. If you are using a different carburetor, your spark advance signal to the distributor will be wrong. An engine will usually bog down when it gets too much air too fast causing a lean condition. Is you accelerator pump working properly?
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| dgmgohl | -- 06-26-2017 @ 5:26 AM |
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Yes, the carb is newer. I bought a rebuilt, bench tested "tea pot", and it was running fine till I changed points, condenser. I did re-set the timing.
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| TomO | -- 06-26-2017 @ 6:38 AM |
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The vacuum hose must be removed and plugged when you are setting the timing. Check inside the distributor for frayed wires that could ground out when the point plate rotates. Check the spark at the plugs for a nice 1/2" sparrk when a plug wire is held close to a head bolt. Tom
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| dgmgohl | -- 06-26-2017 @ 8:09 AM |
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Yes, I did remove the vacuum line before timing. I will check the wire for frayed touches. Thanks.
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| supereal | -- 06-26-2017 @ 9:34 AM |
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The last time I fixed that problem, it turned to be that the nut on the battery side of the starter solenoid had come loose where the big cable connects. The car ran fine until you tried going up an incline, then power was lost. The poor contact reduced the power to the coil.
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| fordv8j | -- 06-26-2017 @ 1:27 PM |
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I put a new napa round coil on my 38 coupe, it would idle fine, but the engine wouldn't rev up, I think it had a built in resister
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| supereal | -- 06-28-2017 @ 1:41 PM |
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The quickest way to diagnose your problem is with a vacuum gauge. If you have access to one, I can provide the chart. Be sure the vacuum is taken from above the venturi rather that from an outlet such as the wiper connection.
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| supereal | -- 06-30-2017 @ 9:53 AM |
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Check your muffler and tail pipe for an obstruction. Tap the case of the muffler with a hammer. If you get a dull thud, the muffler is probably filed with carbon, etc. I have seen mufflers so full that they were very heavy. When they become obstructed, the first sign is a loss of power because the engine can't breathe. Years ago, a common prank was to use a potato jammed into the tailpipe to cause the same situation you report.
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| flathead4rd | -- 07-01-2017 @ 5:28 AM |
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I think your vacuum advance on the distributor may have a leaky diaphragm. Put some vacuum on it and see if it holds. Also check the wire under the points and condenser plate. Also check the condenser. The new ones are cr*p. This message was edited by flathead4rd on 7-1-17 @ 5:30 AM
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| trjford8 | -- 07-01-2017 @ 7:02 AM |
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Is your gas tank nice and clean? If the tank is dirty it could be the pickup tube is obstructed and it's starving for fuel. Had this problem recently with my 54 Mercury.
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| supereal | -- 07-06-2017 @ 12:58 PM |
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One other suggestion: If the exhaust system has a valve, either the thermostatic type with a coiled spring and weight, or the internal "duck bill" valve, odds are that they are stuck nearly or completely from rust and carbon. Look at the rear of he right side exhaust manifold. With the spring type, try to move the lever to see if it is free. The pipe to the muffler must be removed to inspect the other type.. Those valves were intended to aid in warmup by increasing exhaust gas flow thru the intake manifold ports. The best cure is to remove and toss it.
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| sarahcecelia | -- 07-13-2017 @ 5:21 PM |
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Those screws aren't jets! They are idle mixture adjustments, and when they are set, leave them out of the equation!!They only work at idle!! They are really 'Bleed Screws" and when you turn them in they close (BLEED) the gas at idle. If you lose power at a constanly held speed, I would suspect that the main jets are clogged. If you loose power on acceleration, it would be the power valve or the tube in the throat of the carb that is clogged, or partially clogged. It provides fuel when the vacuum drops between idle and power.Look in the throat with the car not running. Move the throttle on the carb and watch the flow that "squirts " down the throat- it should be a little stream that shoots right STRAIGHT down the middle of the throat; if it doesn't, or squirts the fuel on any side of the throat, the car will hesitate on acceleration. If you get nothing, the power valve is shot. Regards, Steve Lee
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| sarahcecelia | -- 07-13-2017 @ 5:24 PM |
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That clogged muffler is a good suggestion; that would definitely cause the motor to "bog down!" Regards, Steve Lee
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