Announcement

Collapse

AVATARS

PLEASE RELOAD YOUR AVATAR. You shouldn't have any problems doing this, now. Thanks again for the delay but now it is over. - Dave
See more
See less

Strange issue when hot advice appreciated

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Strange issue when hot advice appreciated

    Ill try to explain this as straight forward as i can. The car runs perfect upon initial cold startup. And will continue to run fairly well for a while. But after some time and once everything is fully warmed up the engine seems to start to have a small "what im thinking is a" miss. I did a electronic ignition conversion as the car had this issue but on a larger scale before and i found out one of the points went out. So that fixed 92% of that issue. The car is drive able but once hot the idle is a bit rougher sometimes to the point where it has died at a light or in a parking lot. I think i can just barley notice it when cruising.

    So things to know.
    Electronic ignition conversion
    all spark plugs look good
    Cap and rotor are new
    From what i can tell spark plug wires are good
    I have an accel coil
    The ignition ballast is still in place. I believe i have it wired to where the coil has 12v all times.
    Im getting about 13mpg. i swapped out the 3.10 rear gear for 2.75
    I run premium gas with the lead additive
    I do have a tach
    Pretty **** sure i dont have any vacuum leaks
    Running 10w-40 with high pressure oil pump. have 60 psi

    Just kinda scratching my head at this point. Any ideas or suggestiions would be appreciated
    1959 Thunderbird 397ci
    Cruise-O-Matic
    Flamingo Pink.
    Thunderbird Registry #8442
    Daily driver

  • #2
    I would start at the beginning. Put your timing on 6 degrees BTDC and pull the dist. cap. It should point directly at #1 or #6 spark plug tower. If the rotor points in between towers the distributor needs to be removed and reset. Next, make sure your spark plug wires are separated. I've seen spark jump to an adjacent wire. Use those plastic wire separators. Open your hood in the dark and poke the ignition wires with a wooden stick. If sparks are jumping you should hear or see them.

    I don't know the condition of your valves. Lead additive should preserve your valve seats but if one or more are already receded it will show more when the engine is hot. Receded valves hold the valve open. A simple compression test will tell the story. Flat tappet engines depend on ZDDP or cam lobes may wear down preventing valves from opening. A compression check may NOT catch this but by simply looking at the rocker arms move up and down, you can see if a cam lobe is not working.

    After verifying ignition and valve train, you may need a richer mixture. This is harder to troubleshoot from my computer chair but my experience is, when a gas engine starts 'coughing' or 'halting' it may need more gas. Try shading your choke and see if RPMs increase. For vacuum leaks, I take the car outside and wave an UN-lit propane torch around the intake manifold. If RPMs increase you have a vacuum leak.

    I don't know if I would run my coil on 12 volts 100% of the time. Feel the coil. If it gets hot, start using your coil resistor again. The solid state ignition needs the full 12 volts but not the coil. - Dave
    My latest project:
    CLICK HERE to see my custom hydraulic roller 390 FE build.

    "We've got to pause and ask ourselves: How much clean air do we need?"
    --Lee Iacocca

    From: Royal Oak, Michigan

    Comment


    • #3
      Originally posted by simplyconnected View Post
      I would start at the beginning. Put your timing on 6 degrees BTDC and pull the dist. cap. It should point directly at #1 or #6 spark plug tower. If the rotor points in between towers the distributor needs to be removed and reset. Next, make sure your spark plug wires are separated. I've seen spark jump to an adjacent wire. Use those plastic wire separators. Open your hood in the dark and poke the ignition wires with a wooden stick. If sparks are jumping you should hear or see them.

      I will double check but i set my timing at 8 degrees. I am using the spark plug wire seperators. I will check for spark jump.

      I don't know the condition of your valves. Lead additive should preserve your valve seats but if one or more are already receded it will show more when the engine is hot. Receded valves hold the valve open. A simple compression test will tell the story. Flat tappet engines depend on ZDDP or cam lobes may wear down preventing valves from opening. A compression check may NOT catch this but by simply looking at the rocker arms move up and down, you can see if a cam lobe is not working.

      I cant 100% speak to the condition of the valves either. Although when i installed my cam i did hand lap the valves. I do use the ZDDP additive from comp cams. I would ASSUME that if i had a flattened lobe i would be able to see it with the valve covers off when running engine and i would THINK that It would still run rough when at cold idle.

      After verifying ignition and valve train, you may need a richer mixture. This is harder to troubleshoot from my computer chair but my experience is, when a gas engine starts 'coughing' or 'halting' it may need more gas. Try shading your choke and see if RPMs increase. For vacuum leaks, I take the car outside and wave an UN-lit propane torch around the intake manifold. If RPMs increase you have a vacuum leak.

      This doesnt prove anything really but it goes and doesnt hiccup under full throttle or when crusing around 2800 rpm.

      I don't know if I would run my coil on 12 volts 100% of the time. Feel the coil. If it gets hot, start using your coil resistor again. The solid state ignition needs the full 12 volts but not the coil. - Dave
      Ill take a look at some of those things.
      1959 Thunderbird 397ci
      Cruise-O-Matic
      Flamingo Pink.
      Thunderbird Registry #8442
      Daily driver

      Comment

      Working...
      X