Blown BBC intake bolts loose

Discussion in 'PSI Superchargers Tech Questions' started by JetNLed, Jun 10, 2020.

  1. JetNLed

    JetNLed Member

    Joined:
    Nov 16, 2012
    Messages:
    31
    Likes Received:
    0
    I have a few intake bolts that keep coming loose every pass. Blowing oil everywhere

    Blown Alky BBC, 540", flat tops, 30 degrees, 25lbs of boost, power grid ignition, 16v system, Flatout Racing intake gasket.

    What could it be? Detonation? blower out of balance? drive shaft?

    We dyno'd the motor with a 7al-3 box, I believe. So, i wouldnt think i am running out of spark, but maybe I am.

    Greatly Appreciate any help.
     
    #1
  2. kosky racing

    kosky racing Comp Eliminator

    Joined:
    May 11, 2003
    Messages:
    736
    Likes Received:
    36
    Most probable is detonation-
     
    #2
    bandit496 and 32 bantam like this.
  3. kosky racing

    kosky racing Comp Eliminator

    Joined:
    May 11, 2003
    Messages:
    736
    Likes Received:
    36
    Was this assembly balanced-this can cause things to come loose
     
    #3
  4. Bjs344

    Bjs344 Member

    Joined:
    Sep 10, 2013
    Messages:
    270
    Likes Received:
    18
    Nord locks or less timing.
     
    #4
  5. swsc4133

    swsc4133 Member

    Joined:
    Nov 18, 2012
    Messages:
    78
    Likes Received:
    2
    Every time that has happened to us it was a timing issue. And usually when you start looking around it will be something loose, bad wire.
     
    #5
  6. 32 bantam

    32 bantam Member

    Joined:
    Jan 18, 2007
    Messages:
    170
    Likes Received:
    7
    I had that problem when we first started running the blower engine. I bought a tune up and it was REALLY fat!!!. Fuel coming out the pipes during the run Fat. My kept loosening the timing cover bolts. I was running a Mallory III.
    Once I got the tune up leaned out it all went away.
    So it obviously was a misfire issue.
     
    #6
  7. Mike Canter

    Mike Canter Top Dragster
    Staff Member

    Joined:
    Mar 10, 2004
    Messages:
    4,478
    Likes Received:
    151
    Your timing seems to be correct for that engine so maybe to look at you fuel tuneup. You maybe too lean and causing the detonation. What does a set of new plugs look like after one run? What about EGTs at the end of the run?
     
    #7
  8. Bjs344

    Bjs344 Member

    Joined:
    Sep 10, 2013
    Messages:
    270
    Likes Received:
    18
    I went through this for years. One set of heads, only way to keep the bolts tight was to fatten up and back timing down and run 6.60. I could go 6.40 but all the intake bolts would be backed out every run. Red loctite, green loctite, threads clean, torqued, retorqued, didn’t matter. Nordlocks fixed it to where I would have to tighten a bolt every few passes. Egts were super high running 6.60s but they would come down as I added timing and pulled fuel away. Bearings were ok. Could run them forever at 6.60 and a dozen or more passes at 6.40. At 6.60 the puke tank would be dry. At 6.40 it would be full.

    Eventually got my other set of heads fixed. Almost identical except smaller chamber (113 vs 119). I could go 6.20s and not loosen a bolt. Egts were a little lower. Bearings about the same. Puke tank empty most of the time.


    I know it was detonating with the slow heads but I sure couldn’t figure out why so I put them on a bracket car.
     
    #8
  9. Mike Canter

    Mike Canter Top Dragster
    Staff Member

    Joined:
    Mar 10, 2004
    Messages:
    4,478
    Likes Received:
    151
    Bjs344 if you advance the ignition yes the EGTs will drop. The spark occurred sooner so the burn doesn’t go out into the exhaust and the EGT will drop. That is what is confusing and why you should tune by reading the plugs and not by EGTs. If you retard the ignition timing it will move the heat/flame out of the cylinder into the exhaust thereby heating causing the EGTs to rise.
     
    #9
    32 bantam likes this.
  10. JetNLed

    JetNLed Member

    Joined:
    Nov 16, 2012
    Messages:
    31
    Likes Received:
    0
    I was wondering if my msd grid ignition was too weak. I just sent my blower off to have it checked. The timing marks on the plugs look good
     
    #10
  11. JetNLed

    JetNLed Member

    Joined:
    Nov 16, 2012
    Messages:
    31
    Likes Received:
    0
    This motor is making use of the puke tank, about setup in size. I have a quart size tank on it now.
     
    #11
  12. Nitro Madness

    Nitro Madness Super Comp

    Joined:
    Sep 14, 2003
    Messages:
    329
    Likes Received:
    8
    #12
  13. Mike Canter

    Mike Canter Top Dragster
    Staff Member

    Joined:
    Mar 10, 2004
    Messages:
    4,478
    Likes Received:
    151
    JetNLed, regardless of the timing mark how did the base circle color look? Can you email me a picture of a plug looking down at it. Mike.c@mindspring.com. A weak spark will not cause detonation. What plug gap are you running. I hope with that ignition you are using a .015-.016” gap
     
    #13
  14. JetNLed

    JetNLed Member

    Joined:
    Nov 16, 2012
    Messages:
    31
    Likes Received:
    0
    Mike will email pics, NGK - 9s with .018 gap.
     
    #14
  15. JetNLed

    JetNLed Member

    Joined:
    Nov 16, 2012
    Messages:
    31
    Likes Received:
    0
    Also these are brand new brodix BB3 380s Hip treated. I bought them new last year. Motor was balanced and assembled (last year) and this year.
     
    #15
  16. Bjs344

    Bjs344 Member

    Joined:
    Sep 10, 2013
    Messages:
    270
    Likes Received:
    18
    .018 is bigger than I ever ran with my 7al2. .012 -.015 max

    In my experience if it’s putting anything besides water and alky in the puke tank, it’s not completely happy with something.

    For awhile before I changed heads I could tell what the plugs were going to look like within about 5 seconds of exiting the car after a pass. If the puke tank breathers were wet and I could see the intake bolts backed out, I would start hoping I still had 8 straps and would start thinking about pulling the pan. At the very least, I knew I needed to fatten it back up for the next pass. Usually a three thread tuneup but it was the only way I could get those old heads to run a decent number.

    Is this combo putting up good numbers?
     
    #16
  17. JetNLed

    JetNLed Member

    Joined:
    Nov 16, 2012
    Messages:
    31
    Likes Received:
    0
    I am happy with the power, made 1660 on the dyno and was climbing, I run it though at about 7500. EGTs all about 1050s. My logger says they are in the 1250s 1300s. None of the plugs are melted. I thinks its the location of my egts, bottom of the zoomies. I had the blower checked out at Littlefield and they said nothing was out of balance and all was good. I am going to get my driveshaft re-balanced this week just to make sure. I am just baffled. My next tune up will be with 5* less timing and I will add a little to the main jet. We will be in San Angelo, TX with crummy air.
     
    #17
  18. Bjs344

    Bjs344 Member

    Joined:
    Sep 10, 2013
    Messages:
    270
    Likes Received:
    18
    I was always unsure of chicken vs. egg. Did the bolts come loose and that let boost into the crankcase, causing it to push oil and detonate, or did it detonate first, start pushing oil, and that loosened the bolts.

    When I put the nordlocks on, I determined it was probably a little of both but either way those little things are awesome.

    Also at some point I put steel threadserts in the heads and felt like that helped too.
     
    #18
    JetNLed likes this.
  19. kosky racing

    kosky racing Comp Eliminator

    Joined:
    May 11, 2003
    Messages:
    736
    Likes Received:
    36
    14mm belt? How are the bearings in the idler and drive?
     
    #19
  20. JetNLed

    JetNLed Member

    Joined:
    Nov 16, 2012
    Messages:
    31
    Likes Received:
    0
    8mm, Idler bearing feels good to me, snout was inspected at Littlefield and was good, they did put new seals etc in the snout.
     
    #20
    Last edited: Jun 25, 2020

Share This Page