MASSIVE vacuum leak!!!!

Discussion in 'Small Block Tech' started by Cscheibel, Aug 18, 2010.

  1. sean Buick 76

    sean Buick 76 Buick Nut

    Can you back track a bit and explain what is actually wrong with the way it runs? I am having a tough time following what the symptoms actually are.
     
  2. hwprouty

    hwprouty Platinum Level Contributor

     
  3. Cscheibel

    Cscheibel Well-Known Member

    Ok, I'll try and make this a little simpler. I'm going a little crazy so I can see how it's hard to follow. I finally got the motor running. I had an oil pressure problem and it ran really rough. I assumed it was because I hadn't finished timing it yet. I turned it off to address the oil pressure. Got that taken care of the next day.

    Now it still runs rough. I put my hands over the carb to try and make it die which it didn't so I assumed it was a vacuum leak. I checked everything and even resealed the intake. Now it runs a tad bit better and will die with my hands over the carb, but still sounds pretty bad. When I shut the car off it sounds like a huge sucking noise through the carb which I was led to believe indicated I still had a vacuum leak.

    I'm on the verge of just giving up so I can work on the garage and coming back to it when I have the money to go through the whole motor like I should have when I fixed my distributor gear.
     
  4. Smartin

    Smartin antiqueautomotiveservice.com Staff Member

    Where is your timing set, and does the engine smooth out if you rev it above idle?
     
  5. LARRY70GS

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

    If the intake isn't fitting right because the heads/block have been decked, you can have a valley leak, and it will be very difficult to pinpoint. When I am looking for a vacuum leak, I find it very helpfull to hook up a vacuum gauge and watch that as I spray around the intake and sealing surfaces. You can see subltle changes on a gauge rather than listening for a change in the running of the engine. How much vacuum is it pulling anyway? I don't think you have posted that. Those kind of leaks can really be frustrating. Using the composite gaskets in the right thickness can help.
     
  6. Cscheibel

    Cscheibel Well-Known Member


    As near to 4 degrees before as I can, but whoever built this motor forgot to put on a timing indicator. I just really wanted to get it running so I could move it around while I clean my garage and it runs well enough for that. I am not sure I'd have enough money to call TA for the gaskets and timing indicator until I get paid in two weeks. It's frustrating. And yes it does smooth out when I rev it up around 1000-1200
     
  7. Cscheibel

    Cscheibel Well-Known Member


    At idle it's pulling about 15, but it's really erratic. When I rev it up to around 1200 it smooths out around 18 inches.
     
  8. Smartin

    Smartin antiqueautomotiveservice.com Staff Member

    It sounds like your idle circuit is clogged with crap. This a qjet?

    I had a problem VERY similar to this a few years ago with my convertible. It came on suddenly. Everything pointed to a HUGE vacuum leak, but it ended up being crap caught in the idle circuit. I pulled the carb apart, sprayed it out with carb cleaner, blew it out with compressed air and reassembled. Problem solved.
     
    Bogus919 likes this.
  9. LARRY70GS

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

    Which one of these scenarios fits? http://www.secondchancegarage.com/public/186.cfm

    A stock engine should pull about 20"
     
  10. Cscheibel

    Cscheibel Well-Known Member

    Edlebrock carb. Had it on my Electra for a month with no problems so can't see that doing anything to it.
     
  11. Smartin

    Smartin antiqueautomotiveservice.com Staff Member

    Just for giggles, do you have another carb to try on it?
     
  12. Cscheibel

    Cscheibel Well-Known Member

    Not one readily available and I don't want to rob another car the night before work just in case something goes wrong. That is how my luck runs after all.
     
  13. hwprouty

    hwprouty Platinum Level Contributor

    Chris go through the plug wires firing order again, maybe you missed one, easy to do. How old is the fuel in the tank?
     
  14. Smartin

    Smartin antiqueautomotiveservice.com Staff Member

    Don't Edelbrock carbs have idle circuits, too?
     
  15. Cscheibel

    Cscheibel Well-Known Member

    I will admit with all my tinkering and my expensive college degree (Which I just got the other day:eek2: ) I don't exactly know the individual parts of a carburetor. I just know how it works in theory and what not.
     
  16. Cscheibel

    Cscheibel Well-Known Member


    I can't tell you how many times I've rechecked that. I even rechecked my spark plug gap and replaced the older plugs with some relatively new ones laying in the garage. I am thinking of checking the the spark plug wires with my multi meter tomorrow, but I gotta grab it from work since I left it there over the weekend.

    The fuel tank is original and I never cleaned it. The gas is about a year and a half old though. That may be my problem. Should I just disconnect my fuel pump and run a line from the pump into a jug of gasoline?
     
  17. sean Buick 76

    sean Buick 76 Buick Nut

    Drop the tank, get that old fuel out of the tank and start fresh.
     
  18. Cscheibel

    Cscheibel Well-Known Member

    How would I go about disposing of the old fuel?
     
  19. LARRY70GS

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

    Dispose of it like you would used oil. In NY, any service station must take it free of charge. I can tell you this, if you are trying to run a car on 1 1/2 year old fuel, that is your problem right there. Fuel degrades very quickly.
     
  20. Cscheibel

    Cscheibel Well-Known Member

    Alright, I'll get on that this week then and keep you guys posted. I figured gas took a few years to foul up so I'm glad you guys thought of the simple stuff for me. My teacher always tells me to use the K.I.S.S. method (Keep It Simple Stupid):puzzled:
     

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