383 stroker timing/performance and temperature

Discussion in 'Troubleshooting & Diagnosis' started by erhan ergin, Apr 25, 2020.

  1. jeff swisher

    jeff swisher Veteran Member

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    I had dozens of cars with Flex fans and AC and they did not overheat.
    You must use the appropriate fan shroud for the fan or fans being used or like you know it may not be efficient.

    If you still have the flex fan and the shroud spacing is correct I would stick it back on and test it.
    Unless you had issues with heat with that fan.

    The flex fans I use are original equipment Ford flex fans.
    Like this one.
    I drill holes in them to fit the Chevy bolt pattern.
    https://www.ebay.com/itm/FORD-CF-D8...606891?hash=item1ce48e2beb:g:PZUAAOSwwRReUWOs

    Notice the huge pitch of the blades and all the rivets in them.
    And notice the blades are offset ..That keeps them quiet.
    An even spaced fan will make a lot of noise.

    I have spun these to 8500rpm and never had a failure.
    I have ran them at 6500 rpm for over 15 minutes without a break.
     
  2. erhan ergin

    erhan ergin Member

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    The fans are pullers. They are two 12 inch fans. The flex fan I had was a 18 inch unit which worked fine. The classic AC guys suggested this would be a problem going down the highway as the fan blades flatten out. It made sense but I did not check since the AC parts are not here yet. I had the 12 inch fans for another project and thought I would try it. There is one relay for both and they turn on around 180-190 degrees. The temp sending unit is on the intake by the thermostat housing. The fan thermostat switch is by the head. I also have an override so I can turn on the fans with a switch. I plan to hook that override to the AC switch so fans stay on when AC is on. At least that was the plan. With the flex fan the car was running around 210-220. It would not go beyond that.
     
  3. erhan ergin

    erhan ergin Member

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    One more detail the temp gauge is after market. It is probably not accurate but I see the increase in temp from what it was. So relatively to the flex fan perf. the 2x 12 inch are not doing as well. If taking the shroud off does not help I will put the flex fan back.
     
  4. xten

    xten Veteran Member

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    Just as peace of mind, I would verify TDC and check again for vacuum leaks again. I think all this is more than one problem.
     
  5. jeff swisher

    jeff swisher Veteran Member

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    I cringe when temps get above 200.
    Your flex fan should still pull plenty of air at higher rpm.. Yes the fan blades are straightening out but they are also spinning faster and you have air being pushed into the radiator at speed.

    My Ford fans have pitch in the solid section of the fan body and the blades are pretty stiff for a flex fan.

    Another note. You should have some of the blade on the outside of the shroud at all times.
    If the fan is all the way inside the shroud it will cavitate and not pull air efficiently through the radiator.

    The fan inside the shroud all the way will exhale air around the outside of the shroud and not pull as much through the center of the shroud which is the center of the radiator.

    You should be able to hold your hand by the carb and have it blown on by the fan/fans.
     
  6. BC_Homegrown

    BC_Homegrown New Member

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    Sounds like there is more than one thing going on for sure.

    Not sure if you misspoke but turning the Idle A/F screws out (counter clockwise) allows more fuel at idle and would increase the idle speed.

    If you turned them out to a point it decreases idle speed you may be partially flooding it (would explain the fouled plugs).

    A good starting point is 1 1/2 turns counter clockwise from a lightly seated position and adjust your idle from there. Then adjust timing, then back to final adjustment on the carb. If you can dial them all the way in (clockwise) without stalling the motor you may have a blown power valve which would also make it run very rich.

    You may also have too much transition slot showing in your secondary which would cause a high idle.
     
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  7. Lowend

    Lowend Administrator. .a car, a man, a maraca. Staff Member Lifetime Gold Member

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    It's really easy to check if this is a fan issue.
    Drive the car down the street, if you get over 20 MPH and the temps stop climbing than it could be the fan. Over 20MPH, way more air volume is being pushed through your radiator than any fan could provide.

    Not knowing what cam is in this engine is a big issue in this. Assuming you are running something reasonable for a streetcar there is no way you should be pulling less than 10hg vacuum at idle - unless there's a leak.
    I would not spend another 5 minutes on other parts of this project until I could verify the vacuum signal at idle and check for leaks.
    The first rule of mechanical diagnostics is to only change 1 thing at a time.
    BTW leaks can come from a lot of strange places. The most common is the gasket between the carb and intake, followed by vacuum lines, intake manifold gaskets, head gaskets, the brake booster internal to the carb (this one sucks to find)... A smoke test will tell you right away, but assuming you don't want to buy the tools:
    I'd start by putting a vacuum gauge on the car and get a baseline. Then begin spraying (squirts not dousing) around the base of the carb and see if the idle changes. Then the intake manifold to head surface. Then disconnect and cap all of the vacuum lines, if the car runs better, start reconnecting them, 1 at a time until it changes.

    If you can the vacuum of the car solved - than start looking at the other issues.
     
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  8. dave@ztech

    dave@ztech Veteran Member Lifetime Gold Member

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    This/\ , ONLY do one change at a time, as you will not know what change made it better or worse, and you will be like Alice, down the rabbit hole, take your time , and not only will you learn all about your engine , you will see cause and affect sooooo much better, also search youtube for help, lots of info, if you can get through the crazies , HAA HA
     
  9. erhan ergin

    erhan ergin Member

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    OK here are some findings:

    1- TDC marker was correct.
    2- I removed the shroud and the electric fans seem to work fine now. The temp settles just a little over 190F. So one thing I learned, shroud cannot be behind a pull fan. It has to be in front of it.
    3- There are 4 vacuum ports at the back of the carb area.
    - One of the four is on the carb manifold
    - Another is on the spacer between carb and manifold
    - The other two are on the intake.
    - The one on the carb manifold goes to PVC valve. The one on spacer goes to transmission area. The other two on the intake go to the brake vacuum canister and to the HVAC vacuum canister.
    If I unplug any one of them the car revs up and runs faster. When I plug my vacuum gauge I see around 7 Hg. If I advance the distributer it goes up a little but like I said before I am pretty much to the max. I lowered the advance to 18 degrees and vaccum goes to 5Hg range.
    Just to make sure I am referring to inch Hg the gauge also has cm Hg so 5 in Hg is around 14 cm Hg. I wonder when people comment on vacuum if they are assuming inch or cm?

    4- I readjusted the A/F. I seated them and pulled out 1 1/2 turns. I am able to set the idle rpm when car is in gear to ~ 600 rpm.

    Some more questions:
    1- Is it expected that when I pull out the vacuum line the car idles faster. The differences is significant (more than 500 rpm)
    2- I think the car does run better with more advance (more than 18 degrees idle and more than 32 max). I am not sure if I should keep it such that total advance is over 40 degrees. I am worried this could hurt the engine.

    Also with all these adjustments I am still not able to get the tires break loose without using brake and revving up. The higher rpm performance is great but there is very little until I see 3500 to 4000 rpm. There is a stall converter (I am not sure but the stall speed maybe in the 3500 range, someone suggested holding the brakes to see when the tires break loose and that is about when it does).
    It is almost like this engine is built for very high rpm and not much down low.
     
  10. bourbon_scotch

    bourbon_scotch Veteran Member Lifetime Gold Member

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    if you unhook a vacuum line and it runs faster its because your running leaner
    what rear diff. gears do you have?
     

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