What causes Surging?
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What causes Surging?

  1. #1
    What the Hell is That? 72Hondo's Avatar
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    Default What causes Surging?

    I put my motor back together and it surges. I started to think about it and it's always done this since I got the boat. I checked all the usual things vacuum leak around the gaskets etc. sprayed starter fluid around and didn’t get anything. I have had two different sets of carbs on there surges with both. I am running a little 177 blower but I don’t think its big enough to create blower surge. The surge is anywhere from 200-400 RPM and it doesn’t happen quickly it happens slowly. It almost sounds like its going to die but then the rpms pick back up and it idles fine.

    What can cause this?

    Specs: SBC, 30/30 cam, lash 24/26, 177 blower set at 7lbs. Duel 400 carbs. Eletronic Ign.

    Don’t know if you need any more info.
    Last edited by 72Hondo; 07-08-2010 at 07:15 PM.
    Quote Originally Posted by Kyle View Post
    Log off and go float, hang in the party coves, Show and shine on the trailer, fill up the boat, wax it, v-drive, jet, outdrive, and if you got a canoe and your reading this, you sir, need to phucking upgrade.

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    Senior Member GT Jets's Avatar
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    Without seeing, touching smelling and tasting

    It sounds like a hunting distributor advance....Maybe watch the timing while it surges...
    GT


    Quote Originally Posted by Quickjet View Post
    Put a 300 on the back of it, Flywheel it and a nosecone. $15,000 later you'll have a 65 mph pile of shit......

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    What the Hell is That? 72Hondo's Avatar
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    Quote Originally Posted by GT Jets View Post
    Without seeing, touching smelling and tasting

    It sounds like a hunting distributor advance....Maybe watch the timing while it surges...
    Oh yea it’s done it on two different dizzys. Is this necessarily a bad thing?
    Quote Originally Posted by Kyle View Post
    Log off and go float, hang in the party coves, Show and shine on the trailer, fill up the boat, wax it, v-drive, jet, outdrive, and if you got a canoe and your reading this, you sir, need to phucking upgrade.

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    Lord of the Drinks Havasu Hangin's Avatar
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    Blower surge is fat (and happy) at idle.
    "Warming the globe...16 cylinders at a time."

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  7. #5
    gn7
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    Quote Originally Posted by Havasu Hangin' View Post
    Blower surge is fat (and happy) at idle.




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    Senior Member GT Jets's Avatar
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    Quote Originally Posted by Havasu Hangin' View Post
    Blower surge is fat (and happy) at idle.

    Blower surge is vacuum scavenging, not necessarily fat, more of a fat/lean alternation.....Can be tuned out on most, if not all if desired. It is typically how the carburetors are "referenced", if referencing atmospheric pressure on an over driven deal, they can be fun to tune ....(note the sarcasm)

    I don't think your deal is blower surge.....What type of exhaust are you running?
    GT


    Quote Originally Posted by Quickjet View Post
    Put a 300 on the back of it, Flywheel it and a nosecone. $15,000 later you'll have a 65 mph pile of shit......

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    gn7
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    Quote Originally Posted by GT Jets View Post
    Blower surge is vacuum scavenging, not necessarily fat, more of a fat/lean alternation.....Can be tuned out on most, if not all if desired.



    Quote Originally Posted by GT Jets View Post
    It is typically how the carburetors are "referenced", if referencing atmospheric pressure on an over driven deal, they can be fun to tune ....(note the sarcasm)

    I don't think your deal is blower surge.....What type of exhaust are you running?




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    Last edited by gn7; 07-08-2010 at 09:50 PM.

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    Senior Member EVILFORCE's Avatar
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    What is your Dist set-up? Does it have a vacuum advance? If it does burn it. I am leaning toward timing as well.
    No Fool Like A Old Fool is there?

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    What the Hell is That? 72Hondo's Avatar
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    Quote Originally Posted by EVILFORCE View Post
    What is your Dist set-up? Does it have a vacuum advance? If it does burn it. I am leaning toward timing as well.

    It’s a Mallory Comp 9K no vac. advance, set up at 6 initial and 30 total.

    Exhaust is OT bassetts with the bigger primaries.
    Quote Originally Posted by Kyle View Post
    Log off and go float, hang in the party coves, Show and shine on the trailer, fill up the boat, wax it, v-drive, jet, outdrive, and if you got a canoe and your reading this, you sir, need to phucking upgrade.

  12. #10
    Senior Member GT Jets's Avatar
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    Do you have a clue of the camshaft and where it is degreed in (advanced vs. retarded)?

    I would think if it does it with two different carb setups and two ignition systems it would be something done when the motor was built.

    How well does it run up top? What do you have the plugs gapped at? With boost, or a high CR, sometimes you need to narrow the gap of the plugs because it is harder for air to ionize (spark) at a higher pressure...Do you know how much boost there is present at idle?

    I figure if I throw enough darts I'll eventually hit a balloon and win a kazoo or something...
    GT


    Quote Originally Posted by Quickjet View Post
    Put a 300 on the back of it, Flywheel it and a nosecone. $15,000 later you'll have a 65 mph pile of shit......

  13. #11
    What the Hell is That? 72Hondo's Avatar
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    Quote Originally Posted by GT Jets View Post
    Do you have a clue of the camshaft and where it is degreed in (advanced vs. retarded)?

    I would think if it does it with two different carb setups and two ignition systems it would be something done when the motor was built.

    How well does it run up top? What do you have the plugs gapped at? With boost, or a high CR, sometimes you need to narrow the gap of the plugs because it is harder for air to ionize (spark) at a higher pressure...Do you know how much boost there is present at idle?

    I figure if I throw enough darts I'll eventually hit a balloon and win a kazoo or something...
    Thats the way most things are done just F with it until you brerak it further or fix it.

    Plugs are gaped at .35 (NKG, 6 on the heat range) No boost at idle (vacuum gauge) holds about 10-12 HG at idle. As far as the cam, no clue.
    Quote Originally Posted by Kyle View Post
    Log off and go float, hang in the party coves, Show and shine on the trailer, fill up the boat, wax it, v-drive, jet, outdrive, and if you got a canoe and your reading this, you sir, need to phucking upgrade.

  14. #12
    Team CJ460 Just Electric's Avatar
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    do the primary butterflies on your carbs have a small hole in them to lean it out at idle?

  15. #13
    Senior Member Schiada 201's Avatar
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    Sounds like a lean carb, adjust out, maybe air bleeds plugged run some wd 40 thru them.

  16. #14
    cfm
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    Quote Originally Posted by Btnhtillidie View Post
    It’s a Mallory Comp 9K no vac. advance, set up at 6 initial and 30 total.

    Exhaust is OT bassetts with the bigger primaries.
    6° Initial is pretty low.

    Set base timing to where it idles the best and then change your dist advance so that it ends up providing what you want for total.

    Then, go back and re-tune your idle mixture screws. Then carb mods if need be.

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