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EFV-8 Club Forum / General Ford Discussion / Changing positive ground to negative ground

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Posted By Discussion Topic: Changing positive ground to negative ground -- page: 1 2     supereal 01-19-2012 @ 9:15 PM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 The 97 is a temperamental carb prone to internal leakage. The emulsion tube must be in the correct position, and secured with the correct tool. Many have been damaged in trying to repair them. If you are not focused on being "correct", you will find the 94 carb will solve your problems. ellsworth 01-19-2012 @ 5:23 PM reply profile send p.m. Member Posts: 13 Joined: Oct 2010 The problem with the carburetor seems to be with the float. The carburetor is a stromberg 97 and has no power valve like the holly. Am in the process of adjusting the float. According to the repair manual the float may be the problem when the engine is turned off and the it floods in a short time making it hard to start. I'm learning as I go. Will post my results when finished. Thanks TomO 01-14-2012 @ 8:52 AM reply profile send p.m. Senior Posts: 7253 Joined: Oct 2009 Alan, I did not have to set you straight, Supereal did. I did not mention the power valve, because it is better to fix one problem at a time. Doing too many things at once can lead to creating more problems than you have. If this were my car, I would go with a stock distributor set up by Skip, with a coli rebuilt by Skip, change the plugs and then see how the car runs. http://www.fordcollector.com/coils.htm Tom supereal 01-13-2012 @ 8:59 PM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 The simplest way to set idle, as well as diagnose engine problems is with a vacuum gauge. If you don't have a diagnosis list, I can post one. We have lots of expensive diagnosis equipment at our shop, but the good old vacuum gauge is often our choice, particularly when chasing a bad idle problem. ford38v8 01-13-2012 @ 1:42 PM reply profile send p.m. Senior Posts: 2759 Joined: Oct 2009 Smooth running engine only on heavy accelleration indicates a rich fuel/air mixture, confirmed by the sooty plugs. Smooth running can then only be achieved with the throttle wide open, increasing the air intake to match the fuel delivery. Your 13 miles per gallon may have been before this problem started, and is probably less now if the cause is what i think: Pull the power valve and test it in this way: Wash with water, then between your lips, pull a sction on it to your tongue. If it won't hold suction, turn it around and try it the other way. If it won't pass this test, replace it. Note that many new valves won't seat prperly due to a radius at the base of the threads. This must be removed to match the carburetor. Tighten it to the gasket well, or it will leak and show the same symptom as the old valve. The two idle screws at the rear of the carb should be tuned for smooth idle: With fingers only, turn them both clockwise to closed position, and open 1/4 turn. Start the engine and set the idle speed at the side of the carb. Maintain this speed throughout the process. Setting one idle screw at a time, open one till the engine begins to stumble, then close it back to smooth running. This operation will need to be done several times back and forth to even out the two valves. If I haven't got this sequence right, I'm sure TomO will set me straight! Alan TomO 01-13-2012 @ 8:00 AM reply profile send p.m. Senior Posts: 7253 Joined: Oct 2009 Your rough running may be due to the uneven compression. Do as Supereal advised and post the readings here. Replacing a condenser with one that has the same value will not fix a premature pitting problem. Check the points, if the fixed point has the extra metal, increase the value of the condenser, if the movable contact has the excess metal, decrease the value of the condenser. Poor point life can also be caused by incorrect dwell settings. Incorrect dwell settings can also cause rough running and fouled spark plugs. The Mallory distributor has a longer advance curve than the stock 36 distributor, bit with the lower compression and a stock camshaft, this does not provide any extra power. If you are running a super race cam and your engine is operating at or near the top range of the RPMS, you might notice some difference in performance with the Mallory over the stock Ford distributor. Tom supereal 01-13-2012 @ 6:49 AM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 That mileage is not far off, given the age of the engine. As for condensers, if the old points appear in fair condition, we reuse the condenser. Most of those sold today are foreign made, and often inferior. Your plug problem is likely a sign of poor or stuck piston rings, or worn valve guides. If the compression readings on all cylinders are not within 10-15 pounds of each other, it will cause poor idling. Do a dry-wet compression test to see if it is rings or valves that are at fault. Thirty years is a long time, and you are probably lucky it runs as well as you say. ellsworth 01-12-2012 @ 5:24 PM reply profile send p.m. Member Posts: 13 Joined: Oct 2010 Thanks for the info. The engine does not use oil and when I drive it, it gets about 40 or 50 miles on it because the nearest town is 20 miles. The fuel mixture may be too rich, because I'm only getting 13 miles or less to the gallon. The condenser is always replaced when points are put in. The engine has only a few thousand miles since it was over hauled. However that was over 30 years ago. There is low compression in a couple of cylinders and it does run rough at idle or any steady speed. Only on acelleration does it run smooth. Thanks for all the ideas. supereal 01-12-2012 @ 1:34 PM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 We have seen that problem with non stock systems, particularly Mallory. The lack of effective regulation of voltage is the usual cause. Solid state equipment is sensitive to both voltage and temperature. In conventional systems, plug fouling is more frequent when the leads to the coil are reversed and, as Tom points put, the condition and capacity of the condenser has direct bearing on point life. Polarity has little or no effect. Most aftermarket ignitions require full voltage, so be sure you have bypassed the resistor with your Mallory. TomO 01-12-2012 @ 10:37 AM reply profile send p.m. Senior Posts: 7253 Joined: Oct 2009 The only difference in trouble shooting a POS grounded system and a NEG grounded system is in the connection of the meter leads. The Ford distributor is a better unit than the Mallory. Your plugs could be fouled by too much idling or not driving the car long enough (at least 10 miles) after starting it to fully warm it up. The carburetor could also be causing the fouling as well as a weak spark. Most of us have stock Ford distributors and coils rebuilt by Skip Haney. This setup gives a good strong spark and long (typically 15,000 miles) point life. If your points are pitting with less than 1,00 miles, your condenser is the wrong value for your coil and point dwell. Tom

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