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Flathead running rough

Discussion in 'The Hokey Ass Message Board' started by Ilari, May 20, 2013.

  1. Ilari
    Joined: Oct 30, 2009
    Posts: 158

    Ilari
    Member

    I´m new with flatheads and not too much an engine guy. I´ve been playing with four cylinder cars for 20 years, but I´m by no means an expert on engines. Flathead engines are totally new for me.

    I have a 48 Mercury flathead with Strömberg type carburator with electric fuel pump and pressure regulator. I have not checked what is the current fuel pressure.
    Engine has Mallory two point distributor and cables and spark plugs are quite new. I checked plugs and they were dry, maybe a bit more snotty than normally.

    Engine is running rough and uneven, I found it impossible to drive it on idle or low rpm. I plan to disassemble the carburator next, I already checked the points, changed coil and condenser(to another used ones). I plan to buy new condenser, I suppose flathead uses an universal kind of condenser?
    Can you help me? I suppose there is some "do this and that" tips for flathead?
     
  2. Check your ignition leads make sure they are in correct order not crossed, if you have a timing light connected it to every lead one at a time if it is not flashing on certain leads you know that cylinder is not firing.
     
  3. Ilari
    Joined: Oct 30, 2009
    Posts: 158

    Ilari
    Member

  4. Ilari
    Joined: Oct 30, 2009
    Posts: 158

    Ilari
    Member


  5. Petejoe
    Joined: Nov 27, 2002
    Posts: 10,587

    Petejoe
    ALLIANCE MEMBER
    from Zoar, Ohio

    Was this engine running correctly before or have you just acquired it? Don't go to the carb until you check the fuel pressure. Absolutely no more thank 2-1/2 pounds pressure. Also cheap electric fuel pumps are known to change pressure. Be sure the pressure is constant. You may just have dirt in your tank... lots of possibilities.
     
  6. Ilari
    Joined: Oct 30, 2009
    Posts: 158

    Ilari
    Member

    I have some dirt in tank, it´s a model A. :)
    I have a original sediment bowl + new filter before pump. New (used) pump is Mitsubishi, not the cheapest one. I need to check the pressure, I have pressure regulator, but it does not have a "display". Previous pump did hardly fill the regulator, but this new one fills it alright.

    I bought the engine from my friend and as far as I remember it worked fine in his car.
     
  7. jumpinjoe
    Joined: Sep 6, 2012
    Posts: 6

    jumpinjoe
    Member

    Has the engine sat not running for a while ? Could have a valve or two hanging open,might check compression
     
  8. reverb2000
    Joined: Apr 17, 2005
    Posts: 440

    reverb2000
    Member
    from Houston TX

    Put the filter in after the pump. Most electric fuel pumps are "pushers". For the most part, they rely on gravity to get fuel to the inlet. Not saying thats your problem, but at least fix that part.
     
  9. Ilari
    Joined: Oct 30, 2009
    Posts: 158

    Ilari
    Member

    I have now original cowl tank with sediment bowl -> hose to under the passenger floor where is filter + fuel pump -> hose to regulator with filter in cowl on the carburator level.
    I have two filters, one before, one after the pump.

    Engine was sitting 2-3 years, I need to check the compression. When I was finishing the engine for paint, it fell once over. Not high, but from a trolley. No outer damage, hopefully I find no inner damage either.
     
  10. reverb2000
    Joined: Apr 17, 2005
    Posts: 440

    reverb2000
    Member
    from Houston TX

    You say you checked the points and condensor. Was the check a visual? Check you coil and condensor with a digital multimeter. Thats the only way to tell if its working correctly or not. Also if you have a dwell meter you can check the points.
    Use a vacuum guage (is there a port on the manifold?)to see where the vacuum is...that will tell you alot right there. Swapping parts will just waste money. All the info should be on the Vanpeltssales site.
     
  11. If you have any trash in the fuel tank, it will keep plugging the filter. Also most fuel pressure regulators have a port for a small gauge......you really need to know what is going on there. Also agree about the possible sticking valves. good luck
     
  12. rotorwrench
    Joined: Apr 21, 2006
    Posts: 633

    rotorwrench
    Member

    Condensers do not store well. Old Mallory ones were good but new ones not so much. I would find new ones and get more than one to get at least one good part. In Finland, it may not be so easy to find.

    You may have a blockage or maybe a small fuel leak in the carburetor. Clean it out & blow passages clean for overhaul with a kit. Check for warped surfaces between base & body.
     
  13. Just read an article in the July issue 2013 of "Hemmings Classic Car", Tech talk section. The gentleman, Dave Berkemann, responded by stating the fuel pump pushrod was the issue in his car. This happened 50 years ago. His mechanic told him to "take off the fuel pump and pull out the push rod. The mechanic then, " applied a small drop of silver solder to the bottom end, ground it flat" . "Solved the idle problem anlong with vapor locking in the heat."
     
  14. woodypecker
    Joined: Jan 23, 2011
    Posts: 300

    woodypecker
    Member

    I have a model A using the model A tank. It has a filter that goes up into the tank and screens out large pieces of dirt and it can get plugged.
     
  15. I recommend to you, and anyone that has a flathead Ford, to join the sister forum to this one, the FordBarn. There are many flathead experts here, and there are many over at FordBarn. You will get the best knowledge available by being on both sites. Works for me.
     
  16. 40FordGuy
    Joined: Mar 24, 2008
    Posts: 2,907

    40FordGuy
    Member

    Ditto, re; fuel pressure. if you don't have one, be sure to add a pressure regulator, and check it's setting, to no more than 3 PSI.

    4TTRUK
     
  17. Ilari
    Joined: Oct 30, 2009
    Posts: 158

    Ilari
    Member

    I disassebled my carb, Holley 94, and changed injectors or how so you call them. Now there is no idle, I need to change the old ones back. I saw the new ones had one hole less, they were for strömberg 97. I have now fuel pressure meter but could not yet try it.
    I am kind of slow with this, because my garage is in other town.
    I am at fordbarn but hardly never use it, maybe I should. :)
    Thanks all for your advices, I 'll try to figure out the issue more in the weekend.
     
  18. Ilari
    Joined: Oct 30, 2009
    Posts: 158

    Ilari
    Member

    I bought that small filter, but did not change It yet. I should try to rinse the tank at the same time.

     
  19. Petejoe
    Joined: Nov 27, 2002
    Posts: 10,587

    Petejoe
    ALLIANCE MEMBER
    from Zoar, Ohio

    You sir are chasing ghosts. Please check for correct constant fuel pressure before making any changes to your carb.
     
  20. Ilari
    Joined: Oct 30, 2009
    Posts: 158

    Ilari
    Member

    :D I will, carb was clean and recently rebuild.
     
  21. Ilari,
    It is just an internal combustion engine. being a flat head does not make it majic. it has the same requirements as any other engine to run properly.

    If you have a regulator and have no idea what the fuel pressure is then you may as well not have one, put a T in the line right after the regulator and see ahat pressure you are running.

    next and always the first thing you do when one is not running prpoerly is to go step by step through a tune up. make sure that everything is set properly and that nothing inyour normal tuneup is stopping it from running right.

    Now everything is correct you can start eliminating problems with it.
     
  22. Ilari
    Joined: Oct 30, 2009
    Posts: 158

    Ilari
    Member

    I´ve been working with the flathead and had no turning point. I have eliminated the carburator problem and yesterday checked the spark with two different timing lights. Spark seems to be irregular, somehow it´s missing spark time to time.

    I have changed condenser, but the points are still the old ones. They seem to be good, but I ordered new ones already. Cables are silicone and spark plugs are original type and they look fine out. I took the coil out of Volvo, but I suppose there is no difference in 8 cylinder and 4 cylinder coils?
    Mallory distributor is quite new and has no play.

    I´m planning to borrow original type of distributor from a friend and see if it corrects the problem.
     
  23. sewman
    Joined: Jul 17, 2005
    Posts: 248

    sewman
    Member
    from Toledo,Oh

    Have you checked the compression yet?The valves like to stick after the motor has been setting & you might have to take the heads off & put some lube on the stems & tap them down,roll the motor over & tap it down until it frees up.
     
  24. Entlebucher
    Joined: Jun 21, 2010
    Posts: 188

    Entlebucher
    Member

    Did you ever change your spark-plugs?
    Had similar problems with my french-flathead. It turned out, that the 23 year old swiss spark plugs had been the problem.
     
  25. Dan Timberlake
    Joined: Apr 28, 2010
    Posts: 1,271

    Dan Timberlake
    Member

    A voltage drop test across the points with key on and points closed is a good way to judge points condition. Something like 0.3 volts (DC) max I seem to recall.
     
  26. Ilari
    Joined: Oct 30, 2009
    Posts: 158

    Ilari
    Member

    Spark plugs were quite new when I bought the engine, but I have NOS set of champion plugs waiting. I need to change one which seems not to get even spark and that will tell a lot.
     
  27. Ilari
    Joined: Oct 30, 2009
    Posts: 158

    Ilari
    Member

    I have not checked valves, but I tested compression with compression meter. Or what ever you call it. It showed good results to all chambers. I have not taken the heads off yet. I was planning to change heads next winter.
     
  28. Ilari
    Joined: Oct 30, 2009
    Posts: 158

    Ilari
    Member

    I need to try this if the problem continues.

    Summer is too short in Finland, so I decided to buy me a electronic ignition. I bought one of those Hunt Mag-look distributors. I googled a bit and seems to be that there is good and bad experience on them. If someone has one of them, any tips are welcome to avoid the bad experience. :)
     
  29. Ilari
    Joined: Oct 30, 2009
    Posts: 158

    Ilari
    Member

    Unbelievable difference, I changed all spark plugs with uneven spark(6). Now it sounds as it should with hot cam. Still has some noise coming out, hope it's not a valve. Anyway, I'm planning to drive this thing tomorrow. :)
     

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