A little guidance please

Discussion in 'Street/strip 400/430/455' started by 455 Powered, Aug 21, 2017.

  1. 455 Powered

    455 Powered Well-Known Member

    I recently rebuilt my engine and got it broke in. So I decide to play with the timing. I've only got 12 degrees of mechanical advance. 34 total and vac advance is not hooked up. Distributor is an HEI. Very clean and tight. It has a curve kit kit and all advance is in by 2500 rpm running lightest springs. I run a MSD 6AL digital. The problem is it won't hardly turn over when it's at operating temp. of 180 degrees. What should I be looking for? I have a spare HEI but the shaft is pitted. Not where bushings ride though. It needs bushings,the small plastic cover over the grease wells,and grease. What grease should I use if I go this route and where do I get bushings? How do I remove bushings?
     
  2. john.schaefer77

    john.schaefer77 Well-Known Member

    That's a lot of initial timing. Does your distributor have a bushing limiting the advance? Those bushings should be included with any good advance spring kit. That engine is definitely telling you that's too much initial by the slow cranking. It might kick back also.

    I have seen the distributor shaft bushings for sale on a corvette site I called Paragon Corvette. They sell the tool for it.
     
  3. 83T-type

    83T-type Well-Known Member

    34 total with 12 mechanical, so 22 initial? That may be why it's tough to turn hot, possibly starter heat soak too? Maybe less initial, something like 14-16 and get the extra mechanical advance with modifying the distributor? I actually don't know the correct procedure for extracting more mechanical advance from a hei, but somone may chime in with that. Either that or just run a timing retard for starting.
     
  4. 455 Powered

    455 Powered Well-Known Member

  5. Stevem

    Stevem Well-Known Member

    There are 2 problems with those light springs ( most times silver in color) is that they #1) loose tension when hot. #2) fitiuge fast and drop tension quickly!
    The result of this is that they may not be pulling back the mech advance all the way especially if the HEI has old gummed up grease in its advance shaft!
    At what rpm does your advance start to come in?
    For starters once the motor is up to temp install the heavy advance springs and see if cranking gets better.
     
    8ad-f85 likes this.
  6. 455 Powered

    455 Powered Well-Known Member

    Not gummed up. I could spin easily. Advance starts at 1200 rpm
     
  7. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Do you realize that the MSD Digital 6 has a built in crank retard? It is controlled by the cylinder select rotory switch on the side of the box. I believe 2 and 6 are the settings for 8 cylinder. One activates the 20* crank retard, I believe it is 2, but check the instructions. I have my timing locked out at 34*. It cranks at 14* with the crank retard. Yours will crank at 2*, then advance back to 22* over 800 RPM.
     
    8ad-f85 likes this.
  8. Stevem

    Stevem Well-Known Member

    Not how the main Dizzy shaft spins, the adavance shaft as that does move more then 90 degrees if memory serves me right.
     
  9. 455 Powered

    455 Powered Well-Known Member

    No Larry I didn't realize this because I bought mine used and didn't get the manual. Guess I'd better do some online searching. Thanks You always have good advice
     
  10. 455 Powered

    455 Powered Well-Known Member

    Thanks Steve. I misunderstood what you said. I think Larry got me fixed up.
     
  11. 455 Powered

    455 Powered Well-Known Member

    As luck would have it,I have no crank retard and need to buy an external controller.
     
  12. Stevem

    Stevem Well-Known Member

    A lot cheaper to just add a ignition kill switch to allow the motor to start rolling over with no spark, nice anti thrift device too!
     
    8ad-f85 likes this.
  13. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Thought I read you had the MSD Digital 6, not the AL. You can try a different set of weights and center piece to give you more mechanical advance. That will enable you to run less initial advance.
     
  14. 455 Powered

    455 Powered Well-Known Member

    Which weights and center piece should I be looking for?
     
  15. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Got this chart with some research. Found this thread on another forum,

    http://www.chevelles.com/forums/18-engine/327577-gm-hei-centerplate-degree-timing-values.html


    Centerplate# ========== Weight# ===== Crankshaft Degrees*
    ...#346================139==============24*=====
    ...#349================139==============20*=====
    ...#361================139==============24*=====
    ...#363================139==============15*=====
    ...#364================139==============18*=====
    ...#365================139==============06*=====
    ...#368================139==============20*=====
    ...#369================139==============22*=====
    ...#370================139==============25*=====
    ...#375================139==============26*=====
    ...#383================105==============24*=====
    ...#389================139==============21*=====
    ...#393================139==============07*=====
    ...#398================139==============24*=====
    ...#399================139==============25*=====
    ...#400================139==============14*=====
    ...#401================139==============24*=====
    ...#402================139==============26*=====
    ...#404================139==============16*=====
    ...#406================139==============21*=====
    ...#416================139==============24*=====
    ...#417================139==============24*=====
    ...#422================139==============20*=====
    ...#432================139==============24*=====
    ...#438================139==============18*=====
    ...#444================139==============21*=====
    ...#445================139==============19*=====
    ...#446================139==============17*=====
    ...#449================139==============24*=====
    ...#451================139==============20*=====
    ...#452================139==============24*=====
    ...#459================139==============25*=====
    ...#462================139==============19*=====
    ...#467================139==============24*=====
    ...#469================139==============21*=====
    ...#470================139==============24*=====
    ...#481================139==============14*=====
    ...#482================139==============24*=====
    ...#483================139==============24*=====
    ...#485================139==============25*=====
    ...#486================139==============22*=====
    ...#508================139==============24*=====

    You can also try an HEI curve kit like this.

    https://www.summitracing.com/parts/mor-72300
     
  16. 455 Powered

    455 Powered Well-Known Member

    Thanks Larry. We got a bunch of HEI's laying around. I looked at one last night and it had 053 weights so I'm halfway there.
     
  17. Schurkey

    Schurkey Silver Level contributor

    22 degrees of initial timing, all-in by 2500 rpm, and no vacuum advance.

    If this isn't a very lightweight car with deep rear gears, run only on a racetrack, it's got bigger problems than "doesn't crank when hot".
     
    8ad-f85 likes this.
  18. 455 Powered

    455 Powered Well-Known Member

    Still messing with weights and center pieces. Bout ready to change out distributor.
     
  19. CJay

    CJay Supercar owner Staff Member

    Why would you have a problem cranking the engine hot with 12 degrees? That not enough advance IMO to give you a problem. I think I would look more the starting system than a timing issue. The spec on the 70 GS is 10 degrees initial
     
  20. john.schaefer77

    john.schaefer77 Well-Known Member

    I think he is running 22* initial.
     

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