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Featured Technical 350 chev clatter

Discussion in 'The Hokey Ass Message Board' started by jladder, Apr 6, 2019.

  1. 427 sleeper
    Joined: Mar 8, 2017
    Posts: 317

    427 sleeper
    ALLIANCE MEMBER

    I'm thinking now, it might be a form of piston slap you're hearing.
    Or, depending on the cam specs, the valves might be hitting the piston when everything gets up to temperature.
     
    Last edited: May 10, 2019
    partssaloon likes this.
  2. jladder
    Joined: Apr 6, 2019
    Posts: 10

    jladder

    Will have a look at that piston when I get the new heads. Gotta be an optical illusion, that should of been picked up by myself or engine shop while the were replacing the rod bolts.
     
    427 sleeper likes this.
  3. boltupal
    Joined: Dec 27, 2010
    Posts: 247

    boltupal
    Member
    from western ny

    I had a Chevy HD 383 do the same thing. Turned out to be the PCV valve! The rocker started hitting the oil difuser which made the PCV valave slam open and closed.
     
  4. Happydaze
    Joined: Aug 21, 2009
    Posts: 706

    Happydaze
    ALLIANCE MEMBER

    I'm really curious as to that twisted looking piston, assuming of course it's not an optical illusion, but how could it be when the others are clearly in line.

    If it is indeed as it appears it must surely be a manufacturing fault? If it was as a result of something going awry lower down I'd have though it would have manifested itself in catastrophic failure already, unless maybe that was just about to happen? But that's nonsense as that pic is during assembly! Hmmmm. Curious and confused.

    Chris
     
  5. BJR
    Joined: Mar 11, 2005
    Posts: 5,317

    BJR
    Member

    Before you tear the engine apart, remove the mechanical fuel pump and run the engine. Good chance the noise will be gone.
     
  6. Twisted rod ?
    Bad machine on piston?
     
  7. 3banjos
    Joined: May 24, 2008
    Posts: 447

    3banjos
    Member
    from NZ

    Maybe you've stumbled on the wrong website. Early 70's HQ holden, fuck me.
     
  8. Most skirt slap I've had clears up when the engine is warmed up. I had a 307 in a '69 C10 and it did that on cold starts. Engine ran flawlessly otherwise. Get the heads off and you may find something. Cut open the oil filter for shits and giggles.
     
  9. One belly button
     
  10. jladder
    Joined: Apr 6, 2019
    Posts: 10

    jladder

    Maybe I've stumbled across the perfect t platform for some decent advice. I'm asking for ideas on the engine, the shitbox it's in is irrelevant.
     
  11. Pretty much.
    God help us if what “it” came out of or belongs in becomes relevant.
    Every 350 is out of here, every 5 speed, every th350, 200 700.
    I see an engine on a stand
     
    gas & guns and 427 sleeper like this.
  12. 3banjos
    Joined: May 24, 2008
    Posts: 447

    3banjos
    Member
    from NZ

    Actually the so-called shitbox it's in is more relevant to this site than anything. Spreading the traditional gospel certainly rules out HQ Holdens.
     
  13. s55mercury66
    Joined: Jul 6, 2009
    Posts: 3,162

    s55mercury66
    Member
    from SW Wyoming

    Just go back and edit the Holden reference out of your post, drama over.
     
    427 sleeper likes this.
  14. 427 sleeper
    Joined: Mar 8, 2017
    Posts: 317

    427 sleeper
    ALLIANCE MEMBER

    NO SHIT!!! If that's the case, before you know it, all of our buggies will be pulled around by horse's again!!! How's that for Traditional?!?!?
     
  15. 427 sleeper
    Joined: Mar 8, 2017
    Posts: 317

    427 sleeper
    ALLIANCE MEMBER

    Very true, provided the barrel of the piston is in the right spot in relation to the wrist pin. My line of thinking is that, if the pin hole was machined a few thousands off, that it just might have just enough clearance to not be compensated for with thermal expansion like common piston slap and might be the reason it makes a little noise at a "float" type scenario. JMHO. Although I've had extremely bad valve guides make noise like that too.
    I just hope for the OP's sake that it's something simple like a fuel pump or valve guides or a rocker arm hitting something. Chasing noises in an engine sucks!!! Period!!! Hopefully he won't have to yank it out and tear into the bottom end.
     
    Last edited: May 16, 2019
  16. scrappybunch
    Joined: Nov 16, 2011
    Posts: 257

    scrappybunch
    Member
    from nj

    Fuel pump ... the little return spring that keeps everything in place. It's broken, sounds just like a lifter tapping. Been there done that, 1976.
     
    427 sleeper likes this.
  17. jladder
    Joined: Apr 6, 2019
    Posts: 10

    jladder

    Definatly not the fuel pump eliminated that yesterday. Have ordered a summit 1785 cam and lifters (sum-k00172) summit cast steel roller tip rockers and a set of edelbrock e-street heads.
    When these turn up I will chuck em on and that will cover the valve train. If that doesnt solve it engine will come out after planned car run in a few weeks.
     
    427 sleeper likes this.
  18. 427 sleeper
    Joined: Mar 8, 2017
    Posts: 317

    427 sleeper
    ALLIANCE MEMBER

    Please let us know what #4 piston looks like when you get the head's off. The picture you posted earlier has me wondering about things.
     
  19. You can check for a wrist pin knock easily enough. Pull the spark plug wire off whatever cylinder you suspect and run it. The noise will go away without the spark-load on the piston.
     
    427 sleeper likes this.

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