VintAGE-Vans

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BRINGING IT ALL TOGETHER.... A's, G's & E's


4 posters

    Air Flow Issues?

    Stomper
    Stomper


    Number of posts : 53
    Location : Calgary AB
    Registration date : 2013-01-18

    Air Flow Issues? Empty Air Flow Issues?

    Post by Stomper Sun Jun 11, 2017 9:20 am

    I'm the new owner of a 69 display van with a 250 six. It runs poorly and I'm thinking it might be fuel mixture.

    Someone removed the bottom of the air filter housing, exposing the air filter. I've noticed in many photos of G vans the air filter assembly is replaced by a small exposed filter directly on top of the carb. Not sure if this is just for looks. My van starts a lot easier when the dog house is open.

    Are there inherent air flow problems with the G vans? Am I reading too much into this? Should I just focus on tuning the fuel mixture?
    Vantasia
    Vantasia


    Number of posts : 1412
    Location : New Jersey
    Age : 69
    Registration date : 2013-08-18

    Air Flow Issues? Empty Re: Air Flow Issues?

    Post by Vantasia Mon Jun 12, 2017 5:42 am

    Hi, welcome, there are many differing opines on air cleaners...my .02....using a small hot rod cleaner over the hot exhaust manifold makes for rough idle and poorer performance especially at idle in hot traffic.  The factory GM air cleaner with the long snorkel was designed to draw in cooler air from the "cold" side of the doghouse and directly from the fan.  My van came with a little one and I switched to a factory setup and it runs great under all conditions. Yes, there are airflow problems by the overall design of an engine in a box.  The bottom belly pan with its louvers is necessary for proper cooling.  The two side shields extensions from the pan also help, mine runs 5-10 degrees hotter without them in place, I was amazed at the difference when I finally found a pair for my 1st Gen. They apparently help pull the air out of the doghouse at speed. I'm sure GM Engineers ran wind tunnel smoke tests on these vehicles back in the day to figure it all out.  In addition to air flow, good air will do you no good without a fresh clean radiator, either a refurbished stock one, re-cored one or a new replacement, there are several that can be adapted.  If your van has its original 50 year old radiator, get it checked at a shop for clogs...With a good radiator and the pans in place, you should be fine.  Stay away from extra electric fans, they just block the air flow, all just MH(and experienced)O's....
    donivan65
    donivan65
    Governor
    Governor


    Number of posts : 12218
    Location : San Diego, California
    Registration date : 2008-05-12

    Air Flow Issues? Empty Re: Air Flow Issues?

    Post by donivan65 Mon Jun 12, 2017 8:33 am

    Do a fuel test,,,,,,when its running,,,,spray a shot of carburetor cleaner or starting fluid down the carburetor,,,,,,,if the engine runs smoother, you have a lean condition to repair,,,,,,,
    64chevy
    64chevy


    Number of posts : 364
    Location : Rocket Ranch Lompoc, CA
    Registration date : 2008-05-18

    Air Flow Issues? Empty Re: Air Flow Issues?

    Post by 64chevy Mon Jun 12, 2017 11:12 am

    I run those little hot rod air cleaners on my 1st gen vans and never had any issues with them. Run up and down the freeway and around town all day. With that little 6 in your big 2nd gen doghouse you should be getting plenty of air flow. If it starts easier with the doghouse lid off maybe it's boiling the gas out of the carb after you stop it. No air flow. I'd add one of Donivan's "Hamburger fans" to cool it down after stopping. Helps gets rid of that gas smell also.

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    Air Flow Issues? Empty Re: Air Flow Issues?

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