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i never should've messed with it

Discussion in 'The Garage' started by CenTxk5blazer, Dec 15, 2004.

  1. CenTxk5blazer

    CenTxk5blazer Registered Member

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    Within the last few months i swapped my intake for an eldelbrock (sp?) Performer. Since then it's been running like a POS. I connected a vaccum gauge to set the timing (according to previous CK5 post) and even went as far as pulling the valve cover off to make sure i was relatively close to TDC before resetting the dist. I've done this procedure a few times already and have made some progress but it still runs badly.

    I've replaced the cap, rotor, and coil. The spark plug wires are fairly new but not the spark plugs. The truck runs well after initial start up but begins to miss and slows to the point of stalling while idling. It also hestitates every time i try to accelorate.

    Any help would be greatly appreciated.
     
  2. diesel4me

    diesel4me 1 ton status Premium Member

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    Been there--said that!

    You say you put an edelbrock intake on??--or an edelbrock performer carb??(or both!)--need more info--(motor size,type of carb,etc)--you could have vacuum leaks at the base gasket or at the intake gaskets,or many other things can do it--.:crazy:
     
  3. CenTxk5blazer

    CenTxk5blazer Registered Member

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    Swapped Intake.
    Carb: Holley 4150/4160
    Engine Size: 350 or 305 (assume it's a 350).
    This brings me to another question. What's the easiest way to verify the engine size?

    I've checked for vaccum leaks at the intake and have't found any. I also tested the pickup coil and replaced the EGR (emissions testing coming next year) but EGR not connected during this time.
     
  4. slyguy_22

    slyguy_22 1/2 ton status GMOTM Winner

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    I would also check your fuel presure.
     
  5. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    1 step at a time!

    If it was running ok before the swap, only look at things you've touched/changed during the swap.
    Double check your leads are in the right order and double check the timing (it's easy to 'assume' that this'n'that is ok 'cause I did it thismorning)Check you have used/blockrd all the vacuum take offs on the carb (that one near the top of the front bowl is vacuum, not overflow)
    Don't go wasting $ on dist. parts etc when they were working ok before!
    Good luck.
     
  6. K5HIGH

    K5HIGH 1/2 ton status

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    HOW DID U CHK FOR VACUUM LEAKS? TRY COVERING THE CARB COMPLETLY TO SEE IF THIS CHOKES IT OUT. STILL SOUNDS LIKE A VACUUM LEAK TO ME. DID IT HAVE ANY OF THESE SYMPTOMS AT ALL BEFORE INTAKE SWAP? ALSO I THINK THE 350 & 305 HAD DIFFERENT FIRING ORDERS. ANYBODY NO THIS INFO? MIGHT TELL DIFFERENC THAT WAY.
     
  7. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    All Chevy V-8's with a distributor since the fall of 1954 ( new 55's ) have had the 1-8-4-3-6-5-7-2 firing order .
     
  8. diesel4me

    diesel4me 1 ton status Premium Member

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    Motor size info codes..

    There should be an engine code stamped on the front of the block,right under the passenger side cylinder head(most likely right under the altenator,its kinda hard to see)--if you can clean the numbers off,you should see 3 letters at the end like "TDR",or "CSM"--theese are the motor I.D. codes,you can look them up online by typing "chevy engine codes" on google,and it will bring you too websites full of motor codes and other info.
    There is another casting number on the drivers side rear bellhousing above the oil filter (its got BIG numbers,hard to get a look at unless you hava van!might need to use a miror to read it--)--that will tell you only the cubic inch size usually--my 86 305 had "5.0"liter cast into the bellhosing area of the block behind the HEI also...hope this helps you out...

    Might want to take a sample of the gas and make sure its not full of water from condensation while sitting too---..:crazy:
     
  9. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    No, I'm sure they were all 18436572
     
  10. CenTxk5blazer

    CenTxk5blazer Registered Member

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    K5HIGH:

    I used the old trick of listening through a PVC pipe.

    How do you suggest covering the carb completely??

    Prior to the swap it was backfiring through the exhaust until i finally blew out the muffler. I replaced the muffler and adjusted the carb, it did have a slight hestitation problem prior to the swap.
     
  11. mrk5

    mrk5 The Sticker Guy Moderator Vendor GMOTM Winner Author

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    Did you re-tune the carb after the swap?

    If not reset the idle mixture and idle speed. Especially if you changed the timing from where it was before.

    I like to use a hand held tach for this, but you can also use a vacuum gage. Leave everything installed on the carb: air cleaner and all vacuum hookups. Get a buddy (or wife if you can talk her into it;) ) to sit in the truck with the transmission in Drive and holding the break.

    I turn the idle mixture screws in 1/8 increments. If it is already idling rough once it's warmed up, you may need to start by turning the idle mixture screws out. Start by turning them out 1/8 turn and see if the RPMs increase or vacuum increases. I like to give it a minute or two between adjustments to allow for things to settle in. On my brother-in-law's truck the improvement was so obvious we could almost do it all by ear. Basically go in or out, which ever is giving the proper results.

    Keep adjusting the mixture until it stops increasing with each adjustment. Also keep the curb idle screw adjusted so that you are staying near where you want the idle to be when done (remember this is idle in drive). Once the idle stops increasing your there.

    Once your finished take it for a test spin. This should give you the best acceleration from a stop without any stumbles.

    Make sure your timing isn't too far advanced. I've found a tendency to get the timing too far advanced when I've used the vacuum method. You can tell this once you're doing the test drive by making sure there is no knocking.
     
  12. CenTxk5blazer

    CenTxk5blazer Registered Member

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    I reset the mixture using one of those battery powered multi-purpose units (the name escapes me at the moment).

    At idle, it will run fine then the engine speed will decrease then accelerate again to where it was previously.

    I'll go get some of that gas treatment stuff when it warms up later today.
     
  13. surpip

    surpip 1 ton status

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    these guys all explained it better than i could, but the first thing i susspcet is a vaccum leak, or a timing issue whenever the intake and or carb is replaced.

    the easiest way to check for a vaccum leak it to spray the fittings with wd40 or carb cleaner(but that messes up rubber so i like wd40) and listen for a rise in the RPM, but this dosent always work cause the leak might be under the intake. hope i helped a little:dunno:
     
  14. K5HIGH

    K5HIGH 1/2 ton status

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    YA SOME OF THESE GUYS REALLY KNOW WHAT THEYRE TALKING ABOUT BUT FOR YOUR QUESTION COVER THE CARB WITH YOUR HAND CUPING IT AND THE MOTOR SHOULD STALL OR TRY SPRAYING AROUND THE BASE OF CARB AND INTAKE BUT USE STARTING FLUID LIKE THE OTHER GUY SAID HOPE THIS HELPS
     
  15. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    Just another thought!...did you set the float heights? Holleys need to be set up on level ground and it makes quite a difference to how they run.
     
  16. CenTxk5blazer

    CenTxk5blazer Registered Member

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    When the eledelbrock that was previously on it went out, i took it to a mechanic to check the truck out and they replaced the eldelbrock with the holley. So I hope that they set the float right.

    If it comes done to it I'll pull the carb and check it out.
     
    Last edited: Dec 15, 2004
  17. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    Float height adjustment is easy on a Holley. Just slacken off (a bit) the slot head screw on top of the float bowl (the nut under that screw adjusts the float height.)Take out the brass screw on the side of thefloat bowl. Start the engine, or get a buddy to start it. You want to turn the large nut on top until gas just starts running out of the side screw hole. Don't take too long doing it as gas is running toward your headers!!! (have some fire fighting equiptment ready!!! lol
    The front float bowl controls the low speed, rear the high speed (secondarys)
    Don't forget to nip up the screw on top of the big nut and relpace the side level screw.
     
  18. 3 on the tree

    3 on the tree 1/2 ton status

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    Sounds to me like a blown power valve. My F**** had a Holley on it and it backfired one morning, started running rich and hesitating. I took it to a friend who has a shop, and he gave me a new power valve and gaskets. I put the valve in and it solved the problem. Hope you giter done soon!
     
  19. CenTxk5blazer

    CenTxk5blazer Registered Member

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    How can you tell if the power valve is blown?
     
  20. CenTxk5blazer

    CenTxk5blazer Registered Member

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    So far

    I sprayed some wd40 around the intake as well as the base of the carb. As far as I could tell there was know noticeable drop in the RPM. I also took a couple of rags and covered the carb causing the truck to stall. So at least there aren't any vaccum leaks around the carb or top of the intake as far as i can tell.

    I'll play with the timing some more today to see where that gets me. Any other suggestions would be appreciated.
     

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