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Technical my flathead runs like - now.....need help

Discussion in 'Traditional Hot Rods' started by El Batidor del mono, Dec 8, 2011.

  1. hey guys, i have a thread on here since i first got my 1950 club coupe and the progress it has taken so far including the chop me and my buddies did,

    anyway recently it started to play up and now i have exhausted nearly everything to try get it running right again,

    stock 8ba flatty, headers and fenton triple carb intake with 2 operational 97's jetted right down with electric fuel pump and fuel reg.

    this ran fantastic over the weekend of chopped and a little while after then it developed a miss under load,

    i take off in first and it misses a bit, it wont rev out or have a good acceleration of course cause its missing,

    before u start guessing or anything, i have changed, plugs, leads, points, condenser, ballast resistor, taken carbs apart back together, cleaned out fuel pump, fuel reg, blown out fuel lines, new fuel filter, compression test, new wires from ballast to coil, coil to dizzy, checked voltages, new rotor button, new dizzy cap. changed coils a few times, im stumped,
    oh new intake manifold gasket, im goin to try puttin the stock intake back on tomorrow but im not holding my breath on that changing anything.

    any ideas or help would be great, and if ur aussie and u know me, 0402559056 des.

    and even better if u know me and u have a stock 8ba dizzy i could try that would be great.

    cheers in advance
  2. oh and it doesnt have any broken valve springs or anything, but i am scared to think it might be a cam lobe
  3. yellow dog
    Joined: Oct 15, 2011
    Posts: 462

    yellow dog
    from san diego

    You mentioned ballast resistor, I presume that you have converted to 12v then?????
  4. yeah its 12 volt, all voltages at ballast resistor are as to be expected.

  5. yellow dog
    Joined: Oct 15, 2011
    Posts: 462

    yellow dog
    from san diego

    How do the plugs read ....all the same, any wet, black, etc?
  6. just put brand new ones in, at one stage there were two that were a little blacker, well alot blacker than any others but i since fucked with the fue reg and stuff and then they all went a bit black due to to mjuch fuel, new plugs on today
    no change
  7. yellow dog
    Joined: Oct 15, 2011
    Posts: 462

    yellow dog
    from san diego

    You mentioned that you had two plugs "that were a little blacker, well alot blacker"
    as stated. You are changing plugs a lot....I'm not suggesting that its the plugs, but the individual plug readings are key. If they are all sooty or wet you may want to focus on an air/fuel issue. But if only one or two are blackened then begin focusing on only what's unique to those cylinders.
  8. alchemy
    Joined: Sep 27, 2002
    Posts: 16,998


    It's a stock distributor (that's how Americans spell that word), and three 97's? How is the vacuum hooked up to the distributor?

    There are many posts here on the HAMB describing the troubles you will get trying to get good vacuum to an original 8BA distrubtor when running multiple carbs. Most times the advice is to use a mechanical-only advanced "dizzy".

    And, just to make sure, your 3x2 intake does have open plenums to allow you to block off that other carb spot, correct?

    Make sure the closed carb spot is COMPLETELY sealed tight or you will experience a vacuum leak. Just having the butterflies of a dead carb closed will probably leak a bit.
  9. Mr48chev
    Joined: Dec 28, 2007
    Posts: 29,563


    Do you have block off plates under the end two carbs? If you just have the throttle plates closed it may be that you are creating a vacuum leak and running the center carb richer than it needs to be to compensate.
  10. If you're running multiple carbs, you need to replace the stock distributor. One, it works off of venturi vacuum and two (if I remember correctly) the vacuum retards, rather than advances the timing in the dist. I think Bubba does replacement dist. (I know he's on the Fordbarn site) like mopar or chevy's for flatheads or MSD has a drop in plug and play dist (that's what I have) if you're not worried about the size of the dist. cap. They include instructions to set up for flathead. Out of the box may have too much advance.

  11. flatheadpete
    Joined: Oct 29, 2003
    Posts: 10,189

    from Burton, MI

    He's running 2 cabs on a 3x2.....
  12. all great info guys, i am running an old fenton 3x2 intake manifold with 3 97' sitting ontop but inly the 2 outside ones working, the front and back and the centre one is blocked off by plate i cut of 1mm sheet metal with a gasket i cut and also some sealant so i dont think that is leaking, i will double check again, there was already a port drilled and tapped in the side of the manifold for the vacuum to the distributor, yes it advances on idle untill u accelerate and loose vacuum then the distributor retards, sorry i cant have a msd dizzy, im sure it works great but i dont personally like the look of a big fat red msd cap hangin out there, lol, thats just for my car though.

    yes im nearly certain this manifold is all an open plenum, will put a pic up of the setup/

    also just so were clear fellas, this ran awesome and no dramas at all for a while but then it just started this issue without any change to anything, the engine stayed exactly the same and nothing changed.

    thanks heaps for the help though guys keep it coming if u can,

  13. heres a pic of the 8ba, u can see the vacuum port towards the back of the manifold not hooked up in this pic. hopefully this helps a bit

    Attached Files:

  14. Mike51Merc
    Joined: Dec 5, 2008
    Posts: 3,856


    Worse than that--- you have no fuel lines going to your carburetors!

    Just kidding, probably an early photo of your build. Real nice engine compartment. As for your problem, if you have black sooty plugs on half your cylinders then one of your carbs is dumping fuel or not flowing enough air. I had a similar problem and found that one of my choke plates wasn't fully open compared to the other.

    Make sure the carbs are sychronized and that the throttles are opening at the same rates. If you are using "bell cranks" as a linkage, then remember you can't set them at 6 or 12 O'Clock at the idle setting otherwise the throttles will open at different rates. You gotta start with the cranks at about 4 O'clock (for low cranks) or 10 O'clock (for high cranks). I hope this isn't confusing.

    You could block off the outer carbs (or swap manifolds) and run each one of your carbs as a single to test it out.

    You CANNOT use manifold vacuum for the original distributor. Manifold vacuum will cause the distributor advance to work backwards--- it will retard timing on accelleration. Since you are running Stromberg carburetors, you have to either get a distributor with mechanical advance or with vacuum advance designed for manifold vacuum.
    Last edited: Dec 8, 2011
  15. flatheadpete
    Joined: Oct 29, 2003
    Posts: 10,189

    from Burton, MI

    ....Henry is haunting that engine because of that aweful alternator....
  16. Kustom Dick
    Joined: Nov 8, 2009
    Posts: 169

    Kustom Dick
    from Finland

    Do you have stock Cam Gear or new aluminum Cam Gear? That stock fiber gear might broke.
  17. 36tbird
    Joined: Feb 1, 2005
    Posts: 1,083


    I don't see any "inny" and "outy" for the crankcase to breathe. An 8BA should have a down draft tube to exhaust the crankcase fumes with air being allowed in through the oil breather. Does that rear stand have a breather or is it just a fill cap? Early flatheads had the air coming in through the oil breathers at the back then venting out of an outlet on the oil pan.
  18. Larry W
    Joined: Oct 12, 2009
    Posts: 735

    Larry W
    from kansas

    Pull the plugs one more time and check the compression.Always good to know if all is good with the engine ( sticky valves and all that jazz) More than likely you have a ignition problem.
  19. lowsquire
    Joined: Feb 21, 2002
    Posts: 2,564

    from Austin, TX

    First thing to do is change your thinking that "it ran great for a while".
    you are eliminating all sorts of things That could be wrong, becuase of this assumption.
    I promise you the first rule of diagnosis is to STOP ASSUMING ANYTHING.Forget that it ran great..this only hinders you getting to the bottom of whats wrong now.
    now thats out of the way, No one has ever got a load-a-matic to run properly with Manifold vacuum and twin or triple carbs, No-one.
    so fuck that thing off pronto.A standard points chev distributor can be easily modded to work and looks pretty stock
    are you 100% sure that manifold is feeding all cylinders with the centre carb blocked off? becuase it sure as hell wasnt designed to run well like that ..was it?
    I would get a twin carb 8BA one, and hook up a PCV system to the roaddraft tube outlet.
    When you say jetted way far? If you go more than a few numbers below a stock jet thats ok ,but WAY down shouldnt be necessary .045 or .043 would be all you need to do.You may just be super lean, My car ran like you described when I tried to jet down too far.
  20. sunbeam
    Joined: Oct 22, 2010
    Posts: 5,274


    coil ground?
  21. blt2go
    Joined: Oct 27, 2009
    Posts: 551


    you mentioned two plugs were suspect. could someone have switched the two wires. sure makes a good engine quickly run bad. just a thought good luck, you have a deep pool of knowledge here.
  22. AlbuqF-1
    Joined: Mar 2, 2006
    Posts: 909

    from NM

    Any fluid loss? Sounds like a possible head gasket leak. Have you re-torqued the heads (a couple of times)? Which two cylinders?
  23. so what about checking the exhaust valve seats???

    that would be under a typical flathead problem
    rember riding in a ford f100 with a flathead in 1964 long road trip lost a cylinder or 2 further more start droping off and finally we went into coast mode all the exhaust valve seats were cracked at the end
    made it back to tech school with a chain:eek:
  24. wow. plenty of information and questions, i will simply start by saying thanks and im taking all on board, as for compression i have compression tested 3 times all even, before putting the engine back together i re lapped in all the valve seats and changed the seals on the valve stems for intake only i beleuve they were, there was no cracks inbetween the valve seats at all.

    ben, you make an excellent point, i have been trying to look past the point that it was running good and now it isnt but i keep coming back to it as nothing in my set uo has changed,
    yes it is an early flatty intake, wasnt designed to work like that but after a week of road testing before chopped i pulled the plugs they were all burning perfectly and couldnt have been better, when settin timing, i take off the vaccuum line and set base timing to around 8-10 degrees before then connect back up and when reving the advance retard seems to work correct, i am no expert at this shit, everything i have learnt about these flatties i have found out or read since i bought this car thats why i am asking for help.
    trying to think what else people said,
    adjustable johnsons that was a great write up and is super usefull. i can understand that better now as the stock 8ba intake has the vacuum coming off the carb base on the intake, but why was this all performing great before hand>???
    this is what i dont understand.

    should i put the stock intake back on and draft tubes and just run the electric fuel pump to see what happens, as ben would know i have blocked off the push rod tube for the fuel pump,
    also ben they are .43 jets, when i dissmantled all thre 97's they had about 5 different jet sizes ismathced in them one of them even had a .41 and .49 in the same carby.
  25. Mike51Merc
    Joined: Dec 5, 2008
    Posts: 3,856


    You say the "advance retard seems to work correct". I have to disagree. You are seeing movement, but the load-a-matic (original) distributor will move in the wrong direction if connected to manifold vacuum. It would be better to run with the vacuum line disconnected and plugged for a test drive and see what happens.

    The original carburetor (the Holley 94) had a special port that used venturi vacuum for the original distributor. The port is not on the carb base, but rather in the center section above the throttle butterflies. Venturi vacuum increases with accelleration while manifold vacuum drops.
  26. thanks mike51merc,
    i see what ur saying it is operating incorrectly, ok that makes sence, i have test driven it with it disconneted and no changed to the missing at higher revs under load and still no reving out correctly, but what i can take from all this is i need to try the stock carby back on to see how it runs and get a different dizzy for starters if i plan on keeping the 2 97's running....
  27. bykerlad
    Joined: Mar 14, 2009
    Posts: 260

    from australia

    So glad i read this thread, going down the same road......
  28. TraderJack
    Joined: Apr 10, 2008
    Posts: 330


    Ok, first things first.
    Color of exhaust under acceleration? Black, or gray
    Color plugs under acceleration/ Black or brown
    Color of plugs at idle. black or brown

    Tells you is fuel problem, and what is wrong

    Assume electric is okay?
    Check voltage after dropping in resistor. check resistor ohmage!
    Check wire connections for bad wire.

    Stumble on acceleration, plug voltage problem

    Stumble on acceleration, check accelerator pump

    Paint header with temp sensitive paint to see which cylinders are running hot and cold.

    Next check fuel line flow.

    Just more work for you to do.
  29. Rickybop
    Joined: May 23, 2008
    Posts: 7,187

    from Michigan

    Only thing I can add...I would'nt exclude the possibility that the block-off plate is leaking, considering it's made of only 1mm stock. Just another reason to switch intakes for a test. You cleaned and checked entire fuel-sytem except the outlet at the tank. Good luck.

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