383 stroker timing/performance and temperature

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

  1. Bandit723

    Bandit723 Veteran Member

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    I can thank you for posting this issue and sticking with it. got me to look at my setup again. My engine runs cool while cruising down the road but the idling around town is what is getting me. so looked at my timing again. i don't have a lot of options with my dizzy so sure a new one will be in the works but i settled on 24 initial and 36 all in not vacuum advance. while the vacuum advance works i only get a 12 degree sweep with or without it so, it does me no good. What i did gain was a cooler running engine in town. ran it for about 45 mins and never went over 190 much better.
     
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  2. erhan ergin

    erhan ergin Member

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    I am glad if I am able to help in anyway :)
    I took off one plug and here is a pic. It is not rich anymore for sure. I am not sure if it is lean or OK. it is gray. Any thoughts? P_20200523_163141_vHDR_Auto.jpg
     
  3. Bandit723

    Bandit723 Veteran Member

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    well lets see. white porcelain no oil soaking, ring around the porcelain and electrode. ground strap is a bit light. i would say you are close...
     
  4. Rascal

    Rascal Veteran Member

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    My .02; based on my hot rodding experience (circa 1970s), that spark plug appears to have correct combustion chamber Air Fuel Ratio (AFR), it looks good.

    In a correctly operating combustion chamber AFR the spark plug will display the following appearances as described below that was reproduced from the back cover page of the Haynes Automotive Repair Manual for Chevrolet Camaro 1970-1981.

    NORMAL
    Brown to Grayish-Tan color and slight electrode wear. Correct heat range for engine and operating temperature.
     
  5. erhan ergin

    erhan ergin Member

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    I was looking at my pulleys just to get an understanding of overdrive waterpump pulleys. I noticed the following.
    1- The crank pulley has three grooves. The most outer groove is larger than the two inner grooves. The water pump pulley has 2 grooves (6.25 inch). The overdrive waterpump pulleys are around 5.25 inch.
    2- The outer waterpump groove is used by the outer crank pulley and the alternator
    3- The inner waterpump pulley groove is used by the compressor.
    Based on this setup the outer groove wants to rotate faster since it is connected to the larger crank groove. The inner wants to rotate slower since it is connected to the smaller crank pulley groove. Is this normal? I did not notice this before.
    I do get some slippage (squeaking sound) when the engine first starts but then it goes away. I am going to take out the compressor vbelt and see if it makes a difference. The compressor is not hooked up so it is not a real load on the system other than frictional losses.
     
  6. erhan ergin

    erhan ergin Member

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    It appears that the low flow in the radiator was that. The compressor belt was causing the water pump to slow down. I removed the belt and now I can see much better flow thru the radiator. I think the larger pulley which seems to be a separate piece on top of the two groove crank pulley was added to overdrive the water pump. I am really surprised that I was able to drive this as is since these belts should have been continuously slipping although it was only showing symptoms at start up.
     
  7. erhan ergin

    erhan ergin Member

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    This change made about 10 degrees difference. It is around 95 degrees here and city driving brought to temps to just below 210F, before this it was just below 220F. Still not all the way there.
    A few things I found, I need to adjust the secondary throttle plates apparently as holley/summit techs suggest for engines with low vacuum it is needed to adjust the secondary throttle plates and square them also (the transfer slot). I am not sure this will help temps. One more thing I need to check, I thought secondary does not have a power valve but maybe I am wrong. If so I may need to change that as well. I changed the primary from 6.5 to 2.5.
     
  8. Bandit723

    Bandit723 Veteran Member

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    Are you running a AFR gauge? as your vacuum changes they can tell when your power valve kicks in as is visible in the AFR readings. as to adjusting the carb can be a bit of a chase down the rabbit hole. timing is important, looks of the spark plugs are a good take away as to how your engine is running. doubt if timing is spot on and a bit of carb miss adjustment will cause higher temps. are you sure the coolant system is sealed? makes a diff. While i did make changes to my system i am leaking coolant "but knew that for a while" so no longer pressurized and will drive up temps.
     
  9. bourbon_scotch

    bourbon_scotch Veteran Member Lifetime Gold Member

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    you mine as well take those electric fans off now cause obviously they weren't helping and are now just in the way
     

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