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Technical Tech help needed- popping air out carb

Discussion in 'The Hokey Ass Message Board' started by Christie, May 23, 2020.

  1. I have 272 v-8 and cannot get her to start. When cranked she pops air out of the carb and has a burning smell and won’t turn over. I’ve done quite a few things but not sure what else I should try. So far I’ve put in a new fuel pump, new carb, new plugs, wires, adjusted the points, new ignition coil, did a valve adjustment and am still with this issue. Any suggestions would be appreciated


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  2. Wanderlust
    Joined: Oct 27, 2019
    Posts: 787

    Wanderlust

    Was this engine running before the new parts?
     
  3. Truck64
    Joined: Oct 18, 2015
    Posts: 5,325

    Truck64
    Member
    from Ioway

    Did this happen all of a sudden? When was the last time it ran?
     
    Christie likes this.
  4. Hollywood-East
    Joined: Mar 13, 2008
    Posts: 1,993

    Hollywood-East
    Member

    That's a Lot of changed variables, Need the back story to commence...
     
    Christie likes this.

  5. Sounds like a timing issue - did the distributor turn a little by chance ? Pull the # 1 plug - and stick a rag in it - turn motor over until you here a pop - the rag blows out of the # 1 hole - pull the distributor cap and see where the rotor is pointing - should be at the # 1 plug....
     
  6. Wanderlust
    Joined: Oct 27, 2019
    Posts: 787

    Wanderlust

    Another possible is when replacing plug wires is the rotor goes counter clockwise on these engines, I screwed up, started with #1 and went by firing order (clockwise) felt fairly stupid after a bit of investigation.
     
    Christie likes this.
  7. I did pull the distributor out entirely in order to adjust points. I couldn’t see well enough with it still in engine. When I put it back I had crankshaft on tdc, and lowered it with rotor facing to #1.


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  8. She hasn’t run in a couple years. The last time she did run she was dying out on me unless I was pressing on accelerator. So that’s when I changed out everything. The more I’m thinking, the more I’m wondering if I placed the distributor back in wrong???


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    Truck64 likes this.
  9. Stillrunners has a good method also make sure the wires are the correct location plug and capAnd good luck,let us know.
     
  10. 6sally6
    Joined: Feb 16, 2014
    Posts: 2,459

    6sally6
    Member

    Make a piston stop. (Knock the guts out of a spark plug. Run a long bolt thru the middle of the plug. Screw into no.1 cylinder. Turn engine over BY HAND until it stops because piston came up and lodged against piston stop. Mark your balancer. Turn by hand the other direction until the piston comes up and lodges again. Mark balancer. The distance between your two marks is.....TDC)Find TDC....reposition distrib. so the rotor is pointing to No.1 TERMINAL on distrib. cap.
    6sally6
    You would be surprised how many people think 'pointing to no. 1 cylinder' means the actual cylinder on the engine block!
     
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  11. Hnstray
    Joined: Aug 23, 2009
    Posts: 12,355

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    The procedure you outline will locate TDC, but seems to not take into consideration which stroke, exhaust or compression, the piston is on. In any case it is waaay to much work for simply bringing #1 to TDC on the compression stroke. Pulling the valve cover and observing the valves on #1 when the timing pointer is at TDC on the timing mark is all that is normally required.

    Ray
     
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  12. I did all of that found the tdc using a screwdriver in the #1 and positioned rotor to #1 on the cap .


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  13. Truck64
    Joined: Oct 18, 2015
    Posts: 5,325

    Truck64
    Member
    from Ioway

    Agree with the above. Make sure the outer balancer ring of the crankshaft balancer hasn't slipped. Very common on Y-blocks with original balancers.

    A piston stop tool is used to check this, installed in the #1 spark plug hole. Then you know for a fact that when the pointer is aligned with the "0" TDC mark the engine really is at TDC. There are two points where the #1 piston is at TDC, compression stroke and exhaust stroke.
     
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  14. jaracer
    Joined: Oct 4, 2008
    Posts: 2,419

    jaracer
    Member

    You realize that on a Y block #1 is not the furthest forward cylinder. #1 is the first cylinder on the passenger side. I've always brought #1 up on compression stroke by removing the plug and bumping the starter until I feel compression with my thumb covering the plug hole. Then you can use the fan belt to align the mark on the damper.
     
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  15. Truck64
    Joined: Oct 18, 2015
    Posts: 5,325

    Truck64
    Member
    from Ioway

    Assuming the distributor is stabbed in correctly, that still leaves the possibility that the ignition timing is way off, due to a possible slipped balancer ring. The timing marks move with it. A piston stop tool should be used to check this. Any original equipment balancer needs rebuilding or replacing by now.
     
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  16. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 5,216

    2OLD2FAST
    Member
    from illinois

    Start with a compression check . Stuck , bent or burned valve would act this way ....
     
    Christie likes this.
  17. How can I do a compression check if the car won’t even run? I thought you do that on a warmed up engine? No?


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  18. Dave Downs
    Joined: Oct 25, 2005
    Posts: 935

    Dave Downs
    Member
    from S.E. Penna

    You can do a cold compression check, numbers may be low but you will see a dead cylinder with a stuck valve
     
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  19. Check your TDC compression as said to at least see that you haven’t put the distributor 180 degrees out, easily done. Plugs out ,turn it over with a thumb over number 1 ,wait for compression to build up then with a screwdriver or whatever to check ,get the piston at the TDC and check the rotor position then, once confirmed,look elsewhere.
    When confirmed at least you can move on.
    Always look at what you changed last before the start of your problem.
     
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  20. Ericnova72
    Joined: May 1, 2007
    Posts: 595

    Ericnova72
    Member
    from Michigan

    Perhaps you aren't getting this fact clearly....TDC comes up twice in every cylinder for just one distributor rotor rotation.
    Screwdriver will find a TDC...but was it TDC firing.... or TDC pushing exhaust out?? Big difference between the two. 180° difference to the distributor.

    From your description of engine behavior, It sounds like you have the distributor rotor 180° out of alignment.
     
  21. southcross2631
    Joined: Jan 20, 2013
    Posts: 4,413

    southcross2631
    Member

    If you have access to a leak down tester that will tell you if you have a valve issue. If it didn't back fire through the carb when you parked it then you probably caused it by pulling the distributor . Have you checked to see the timing chain hasn't jumped ?
     
    Christie likes this.
  22. Thank you everyone, can’t wait to get back out there today and try again!! I’ll update you guys


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  24. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,263

    gimpyshotrods
    ALLIANCE MEMBER

    I have had three Y-Block equipped trucks towed in to the shop because of this, so it is not that unusual to find this as an issue.

    It does not help that different manufactures start numbering in different places, and in different patterns.

    [​IMG]
    Oh, and often have distributors that rotate the other way, too.

    What is cylinder #5 on a Y-Block is cylinder #1 on a Chevy. It may be as simple as having the plug wires on in the wrong positions, wrong order, or both.

    It happens, even to the most dyed-in-the-wool old-school car guys, who will never, ever admit that they did that.
     
    Last edited: May 24, 2020
    Blues4U, scotty t, 1Nimrod and 3 others like this.
  25. I’ll have to do some reading on this. Ty! Gonna be heading out there soon, pray for me


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  26. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,263

    gimpyshotrods
    ALLIANCE MEMBER

    Putting a distributor back in is also not all that uncommon. A whole lot of them drive the oil pump, via the roll pin that holds the distributor gear on. Others drive the oil pump with a hex shaft, so you get SIX chances to put it in, instead of TWO, and only one is correct!

    I put a distributor in an Chevy, 180º out-of-position, at the end of last year, and I have been at this for bout 40-years.

    I am much less inclined to believe that you have a stuck valve. I would check over the work you have performed, first.

    The Occam's Razor Principle is an abductive heuristic that basically states: The simplest explanation is most likely the correct one.
     
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  27. jaracer
    Joined: Oct 4, 2008
    Posts: 2,419

    jaracer
    Member

    When I first bought my 57 T-Bird I hadn't worked on a Y block in many years. I replaced the points and was trying to set the timing, but I could never see the marks. I ended up setting it with a vacuum gauge. A year or two later I realized I had the timing light connected to number 5 cylinder.
     
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  28. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,263

    gimpyshotrods
    ALLIANCE MEMBER

    Of folks who have tuned Y-Blocks, there are only two types:

    Ones who readily admit to having done this, and liars.
     
  29. squirrel
    Joined: Sep 23, 2004
    Posts: 55,934

    squirrel
    Member

    huh? it's a ford V8, number one is on the pass side.
     
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  30. sunbeam
    Joined: Oct 22, 2010
    Posts: 6,213

    sunbeam
    Member

    To check pull the drivers side valve cover watch the valves on #6 second one from the front. Turn the engine when the exhaust is closing and the intake is starting to open you are very close to TDC #1 check timing mark If not close say 10 degrees Damper may have slipped or cam jumped time and check if rooter is pointing at Number 1.
     

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