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One side of block not firing

Discussion in 'The Hokey Ass Message Board' started by HomemadeHardtop57, Aug 24, 2012.

  1. HomemadeHardtop57
    Joined: Nov 15, 2007
    Posts: 4,250

    HomemadeHardtop57
    Member

    I have a 350sbc in my model a. I'm running the middle two carbs on a 6x2 intake. At idle the driver side of the block does not seem to be firing. When I hit the accelerator pedal and get the rpm's up the driver side fires but pops and carries on with a little black smoke too.

    Today I tried to find the problem by process of elimination. I tightened the intake manifold bolts, mounting bolts on all 6 carbs, rebuilt the two middle carbs, replaced the plugs, replaced the points, rotor and distributor cap. Shot around the intake with carb cleaner to look for vacuum leaks too

    Still runs the same... Driver side not firing at idle...but kicks in when rpm's are up. Anyone have any suggestions what else I could look for.
     
  2. Master of None
    Joined: Dec 18, 2009
    Posts: 2,279

    Master of None
    Member

    Sounds like you need to do a compression check next. Could be bent valves? flat cam? or bent push rods. I'd do a compression check to rule out any holes in pistons or broken rings.
     
  3. junk yard kid
    Joined: Nov 11, 2007
    Posts: 2,718

    junk yard kid
    Member

    Could be a worn distributor bushing, could be a lot of things. Maybe switch the carbs see if the side changes.
     
  4. F&J
    Joined: Apr 5, 2007
    Posts: 13,221

    F&J
    Member

    Might be just a carb issue you missed. Are those 2 carbs similar for linkage, so you could swap sides? Then see if the same bank is still dead.


    on second thought; at idle, warmed up a bit. How about using your hand with fingers spread just a bit, to cover/choke the carb a bit....just to see what happens..
     

  5. Is that intake a shared Plenum or bank designated?
    Try swapping carbs and see if the problem follows.
    Is this a new problem?

    You guys type fast
     
  6. Johnny Gee
    Joined: Dec 3, 2009
    Posts: 10,097

    Johnny Gee
    Member
    from Downey, Ca

    Is this something new?, as in did you just put that set up on the car and now it runs as you describe but ran fine before with a single carb intake.
     
  7. olds vroom
    Joined: Jan 29, 2010
    Posts: 984

    olds vroom
    Member

    Could be a bad coil
     
  8. LUX BLUE
    Joined: May 23, 2005
    Posts: 4,407

    LUX BLUE
    Alliance Vendor
    from AUSTIN,TX

    So, 1,3,5, and 7 aren't firing?

    Do they have spark at idle? (I bet they do.)
    Try this. Swap the carbs from side to side. If the problem switches sides, it's the carb. If not, there are a few things to check.

    The lifters on that side of the block are the only shared mechanical aspect of the entire side of the motor, and reactive to oil pressure. If that is acting bad on that bank (which would explain the reaction to r.p.m. - more r.p.m., more oil pressure) this is the likely culprit.

    Or you have a red rag stuck in the manifold.
    Possibly gremlins.


    Sent from my DROID device using the TJJ mobile app
     
  9. HomemadeHardtop57
    Joined: Nov 15, 2007
    Posts: 4,250

    HomemadeHardtop57
    Member

    Thanks for the suggestions. Its an edelbrock cross ram. I tried switching carbs side to side too , still the same. If I put my hand on the driver side carb there is good suction and it will retard the rpm's. On the passenger side carb there is much less suction and the rpm's aren't affected with my hand over the mouth. I'm running Ford 94s. The intake setup has been running strong for two and a half years so this is a new problem on the same set up. I did a full cleaning/rebuild on the carbs anyway..but like I said still the same
     
  10. LUX BLUE
    Joined: May 23, 2005
    Posts: 4,407

    LUX BLUE
    Alliance Vendor
    from AUSTIN,TX

    I wonder if the galley plug behind the timing gear backed out.

    Sent from my DROID device using the TJJ mobile app
     
  11. All of a sudden, like it was fine yesterday-
    Or last time you had it out , a year ago , it was fine?
     
  12. HomemadeHardtop57
    Joined: Nov 15, 2007
    Posts: 4,250

    HomemadeHardtop57
    Member

    Last time a drove it was one week ago. I drive the crap out of it though, several times a week for the past couple years.
     
  13. F&J
    Joined: Apr 5, 2007
    Posts: 13,221

    F&J
    Member


    Not up on that intake; are the right and left banks isolated from each other? If yes, then it sounds like very low compression on one bank?
     
  14. I think lux is on the right track - lifters and oil pressure on that side
    Could be something made a nest in there or exhaust when you weren't looking.
     
  15. gerry miller
    Joined: Feb 3, 2012
    Posts: 108

    gerry miller
    Member

    Simple answer might be a blockage in the exhaust on that side.Could even be in the exhaust manifold. Or a collapsed inner exhaust pipe. You can't see it from the outside.
    Hook up a vacuum gauge might help. Good luck. Gerry
     
  16. LUX BLUE
    Joined: May 23, 2005
    Posts: 4,407

    LUX BLUE
    Alliance Vendor
    from AUSTIN,TX

    Good answer. The ol nanner in the tailpipe syndrome.

    Sent from my DROID device using the TJJ mobile app
     
  17. olds vroom
    Joined: Jan 29, 2010
    Posts: 984

    olds vroom
    Member

    Ant update on this problem?


    Posted from the TJJ App for iPhone & iPad
     
  18. We found a mouse condo inside the muffler on a Camaro once. Made a huge difference once we evicted them. Found a mouse CARCASS mummified in a NOS radiator once, too.
     
  19. HomemadeHardtop57
    Joined: Nov 15, 2007
    Posts: 4,250

    HomemadeHardtop57
    Member

    Still chasing the problem. We're going to do a compression test tonight and plan on pulling the valve covers to inspect the heads.
     
  20. Since putting your hand over the carb had no effect and suction was low your compression will be low on that side

    What have you done so far ?
    Check for obstruction?
    Check for oiling on that side ?
    Other ?
     
  21. Or it has a plug out in the back of the block.

    I would run a vacumm meter on both sides as well, the amount of vacumm you pull can be very enlightening. Give me a minute to find my note book on reading vacumm and I'll be back.

    Too damned many note books, I wish I had never kept notes on anything. :eek:

    Ha found it second try, this is what I have written from when I was in high school and still trying to learn to diagnose by feel.

    0-10 inches indicates either a valve or vacumm leak. No vacumm leak will then indicate that you are having a valve problem of some sort, either bad valve timming or in your case where it is bank sensative it could indicate burnt or bent valves, or failing lifters or bent pushrods. 14-18 inches indicates that you are timmed a little slow and the 18-23 inch range is good.

    now all this is given that you are running a pretty stock engine and I am going to say that you want to watch for a very slow vacumm signal as an indication of a valve problem, as described above.

    It never ceases to amze me thst stuff I have scrawled in note bokiks and on scraps of paper. On this page I have written low vac = bent pushrods on FE. I must have had an FE with a problem?
     
    Last edited: Aug 27, 2012
  22. Mart
    Joined: Mar 3, 2001
    Posts: 4,643

    Mart
    Member

    Has one of the other carbs on the "bad" side become unblanked?? - sorta thinking big air leak on the bad side so no vacuum for the working carb.
     
  23. What's the scoop on this one ?
    Any updates
     
  24. HomemadeHardtop57
    Joined: Nov 15, 2007
    Posts: 4,250

    HomemadeHardtop57
    Member

    Yea. The power valve plugs in the carbs were leaking. It was just sucking raw fuel down into the block through the vacuum hole in the carb plates , and fouling out the plugs. The oil was super thin too from all the gas. All fixed up now. I think the gaskets didn't like the fuel it was getting the past few years
     
  25. Glad you got it fixed, but I would have never guessed the carb with the left right swap and problem stayed.
     

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