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Sbc new cam and heads won’t start!

Discussion in 'The Hokey Ass Message Board' started by Camp64, Jul 31, 2019.

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  1. Camp64
    Joined: Jul 31, 2019
    Posts: 18

    Camp64

    I put perfectly fine running double hump heads and a fresh solid lifter 30-30 cam with a Edelbrock performer intake and a Holley 650 double pumper. I’ve taken it apart and back together a few times now and still no luck. Timing is dead on I’ve triple checked installing the timing gear and can’t keep from back firing out of the carb to save my life. Put on a stock 2 barrel intake and carb and was able to run but not idle due to bad carb. My guess is my intake is warped.
     
  2. Camp64
    Joined: Jul 31, 2019
    Posts: 18

    Camp64

    It’s a Sbc 327 with flat top pistons .40 over. Not a fresh rebuild but ran decent when I decided to upgrade. Hei distributor
     
  3. You need to do an intro post first.
     
  4. southcross2631
    Joined: Jan 20, 2013
    Posts: 2,932

    southcross2631
    Member

    Timing, firing order , blown power valve. wrong valve lash.
     
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  5. Oldioron
    Joined: Dec 12, 2018
    Posts: 920

    Oldioron
    Member

    Intake valve holding open, tight guide.
     
  6. I agree. Check the valve lash. You may have the rocker arms too tight.
     
    427 sleeper likes this.
  7. Mike VV
    Joined: Sep 28, 2010
    Posts: 1,579

    Mike VV
    Member
    from SoCal

    For people to help with any sense of accurateness, the requester NEEDS to get the details correct and complete..!

    Camp64 -
    You do NOT have .40 pistons, as you note..! No such thing.
    You may have .040" pistons though..!

    "Timing is dead on".
    What does this mean ? "Dead on" what ? The distributor is set to...one degree, five degrees, 12 degrees ? And where, at the crank or total ?
    Or...are you talking the timing gears ?
    How are we to know what you are talking about ?

    Mike
     
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  8. Camp64
    Joined: Jul 31, 2019
    Posts: 18

    Camp64

    Timing was set using the finger over the number one cylinder method. Adjusted while cranking the car and got it where the car was to fire but would just back fire out of the carb even if adjusted further.i have the valve lash adjusted .030 and .030 as what the cam card says and it being a 30-30 cam. The timing marks on the crank pulley and the cam pulley were dot to dot and then turn the motor over so that Both cam and crank dots were pointed at 12 o clock when at TDC. It was a new running power valve in the carburetor a week before this is taking placing.
     
  9. Bandit Billy
    Joined: Sep 16, 2014
    Posts: 5,452

    Bandit Billy
    ALLIANCE MEMBER

    And you dropped the distributor at that location? I think you are 180 out. But on the good side it means you are half right.
     
  10. shivasdad
    Joined: May 27, 2007
    Posts: 519

    shivasdad
    ALLIANCE MEMBER
    from Texas

    180 out was my first thought as well. Also valve lash. I had an inline six that I adjusted the valves too tight and it would never fire. Made some good explosions in the muffler until I figured it out though.
     
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  11. I will third the 180 out. I speak from experience...:oops:
     
  12. Camp64
    Joined: Jul 31, 2019
    Posts: 18

    Camp64

    When it is at tdc on the compression stroke(finger blown out of number 1 cylinder) I drop the distributor pointed at number one cylinder and adjust timing when cranking.
     
  13. Camp64
    Joined: Jul 31, 2019
    Posts: 18

    Camp64

    It was also able to run pretty decent with just a stock 2 barrel intake with a Rochester on it but when I switched it back over to this carburetor and intake it back fires through the carb again with out firing for more than a few seconds
     
  14. saltflats
    Joined: Aug 14, 2007
    Posts: 9,510

    saltflats
    Member
    from Missouri

    Did it by chance have a crank timing gear with more than one key way in it?
     
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  15. Are you certain that the plug wires are in the correct order? 5 and 7 often get crossed.
     
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  16. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 1,725

    2OLD2FAST
    Member
    from illinois

    What method did you use to adjust valves ?
     
  17. Camp64
    Joined: Jul 31, 2019
    Posts: 18

    Camp64

    Yeah I've checked the spark plug wires for an hei distributor on google image diagrams many time. The crank pulley had 3 key ways and I set it to 0 with the other options being Advanced or retarded I like 4 degrees. When setting valve pash I used the method at tdc on number 1 cylinder and tdc on number 6 cylinder.
     
  18. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 1,725

    2OLD2FAST
    Member
    from illinois

    Do you have someone you trust who could take a look , fresh eyes , you've obviously made an error along the way and now you're missing it ..... Get away from it for a couple days , read through all the procedures , you can guess or speculate till you're purple , it's still a guess.!

    My guess is dist. A tooth off ..
     
    Last edited: Jul 31, 2019
  19. "Both cam and crank dots were pointed at 12 o'clock when at TDC"

    I thought the dots were supposed to be opposite each other on a SBC......crank at 12, cam at 6. Your cam is off by 180 degrees.
     
  20. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 1,725

    2OLD2FAST
    Member
    from illinois

    Cam at 6or 12 , crank at 12 is the same , it's just #1 or#6 firing position , generally , with the cam & crank at 12 , that's #1 firing position
     
  21. Camp64
    Joined: Jul 31, 2019
    Posts: 18

    Camp64

    Alright thanks everybody one last thing do you think that a bad intake leak could cause this problem. Fires for a second or two and then back fires out of the carb if everything is possibly correct
     
  22. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 21,683

    Bruce Lancaster
    Member Emeritus

    I think "Fresh Eyes" a couple posts up is a very good way to reboot this.
     
    Moriarity likes this.
  23. Budget36
    Joined: Nov 29, 2014
    Posts: 2,322

    Budget36
    Member


    Just to clarify, after you felt compression, you continued to roll the engine over until the piston was at the top of the stroke, right?
     
  24. Camp64
    Joined: Jul 31, 2019
    Posts: 18

    Camp64

    Yeah and the mark on the crank was at 0
     
  25. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 1,725

    2OLD2FAST
    Member
    from illinois

    No,
     
  26. badvolvo
    Joined: Jul 25, 2011
    Posts: 367

    badvolvo
    Member

    No, bad intake leak won't do that. It does sound like 180 out is a possibility, but again, how did you adjust the valves?
    Pull the valve covers, do a search on google for EOIC valve adjustment and do that. When your done with the valve adjustment, go back to #1, watch the intake valve open and close, continue to turn to TDC then do your dist install.
     
  27. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 1,725

    2OLD2FAST
    Member
    from illinois

    As a rough check for valve adjustment , run a compression. check ...
     
  28. 1946caddy
    Joined: Dec 18, 2013
    Posts: 1,491

    1946caddy
    Member
    from washington

    Pull the number 6 plug and do the finger test until it blows your finger off the plug hole, where is the rotor pointing ?
     
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  29. Camp64
    Joined: Jul 31, 2019
    Posts: 18

    Camp64

    I set number one to tdc and adjusted exhaust 1,3,4,8 and intake 1,2,5,7 and then number 6 tdc adjusted exhaust 2,567 and intake 3,4,6,8
     
  30. Atwater Mike
    Joined: May 31, 2002
    Posts: 9,776

    Atwater Mike
    ALLIANCE MEMBER

    A novice came to my shop, explained much of the same. He said he 'pointed the rotor to #1 after determining engine was TDC, #1.
    I asked, "Are you sure it pointed to #1 contact in the cap?"
    He said, "No, pointed it to the #1 plug, at the drivers side front of engine!"
    More than once I have heard of this...
     
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