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Smoking when I hit high Rs, just wondering

Discussion in 'The Garage' started by sled_dog, Apr 25, 2003.

  1. sled_dog

    sled_dog 1 ton status

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    When I rev up my engine and it hits about 6000 RPMS it shoots a puff of smoke. If I hit like 5000 it doesn't happen but it does way up there. This is a brand new completely rebuilt 355. Heads were redone as well as every other part.
     
  2. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Is it broke in yet?

    Rene
     
  3. sled_dog

    sled_dog 1 ton status

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    yeah have about 1200 miles on it. I didn't hit said RPMs till like 800 or 900 miles. I let a friend rev it up casue I wanted to hear the exhaust from outside and he revved it higher than I normally do. It sounds really good up at those RPMs but I don't dare hold it there or rev it that high much. Especially with this smoke thing. I changed the oil at about 1000 miles(my engine builder said to at 700 /forums/images/graemlins/frown.gif)
     
  4. 82TOYLB

    82TOYLB Registered Member

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    Could it be that at that RPM you are starting to float your valves so that some oil from the top of the head gets down into the cylander and then exits via the exhaust as white smoke? Just don't push it to 6,000 RPM anymore. Wheeling and acceleration are a lot about torque/gearing /forums/images/graemlins/thumb.gif anyway.
     
  5. heavy4x4

    heavy4x4 1/2 ton status

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    That was my first thought, but that would mean oil is passing through the valveseals which is unlikely.
     
  6. sled_dog

    sled_dog 1 ton status

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    see thats my thing, I was thinking yeah ok just floating the valves and going passed the valve seals but the heads were just rebuilt 1200 miles ago. I don't plan to hit that RPM much but its really tempting since it sounds really good up there. I need gears in the worst way. A running race starting at like 45 in third gear today I took my friend in his Cummins 2500 Dodge with upgrades. Standing start he leaves me in a cloud of smoke about 30 seconds behind him.
     
  7. 82TOYLB

    82TOYLB Registered Member

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    Do you think that at that RPM the valve stems are starting to deflect just enough to make the seal temporarily incompetent and thus the smoke? Just a thought I really don't know.
     
  8. ben427

    ben427 1/2 ton status

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    I think you hit the nail on the head, Around here at the 4x4 races all the trucks blow smoke at high rpms(6500-8500), even with new guids and seals. It was explained to me that all the oil get up to the heads really quick, but cant get back to the base as quick, so a bunch of it will pour down the valve guides into the chamber and burn off. After the truck has burnt it off after the race the smoke is gone.
     
  9. sled_dog

    sled_dog 1 ton status

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    makes sesne it may happen for me I have a nice high volume oil pump so I am prolly puting a little bit more up there too.
     
  10. BigBurban350

    BigBurban350 1/2 ton status

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    When the cylinder bore is tapered due to normal wear, the piston ring expands as it reaches TDC(top dead center) and contracts when it reaches BDC(bottom dead center). Now when the pistons speed is to fast, the ring does not have enough time to expand as it reaches TDC allowing oil to pass into the combustion chamber causing the smoke.

    Your valve seals are a possibility also, and is more apparent on engine decel due to the throttle plates being close and the large vacuum created sucks the oil past the seals. /forums/images/graemlins/usaflag.gif /forums/images/graemlins/burb.gif /forums/images/graemlins/usaflag.gif
     
  11. sled_dog

    sled_dog 1 ton status

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    I am sure its not the thing you just said about the engine broe cause my block was just bored .030 over when I rebuilt it.
     

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