Boosted Buicks Here!

Discussion in 'High Tech for Old Iron' started by sailbrd, Sep 24, 2010.

  1. sailbrd

    sailbrd Well-Known Member

    Forget regular gaskets and go Cometic. Also I am not sure that a mechanical pump can keep up. Going lean is not a good idea.
  2. Michael Evans

    Michael Evans a new project

    What are you doing for head gaskets "islandbum" ?

    I bet that is why you popped a head gasket (mechinal pump).

    You got lucky because when you go lean at high RPMs, you burn up a pistons.

    While you have the engine apart (take off both heads) check the piston tops for deformation.

    Before you start it, you should upgrade the fuel system.
    Last edited: Nov 21, 2014
  3. stubnosebrock

    stubnosebrock Well-Known Member

    Just out of curiosity, but why would a quality mechanical pump be any different than a quality electric for a boosted app?
  4. sailbrd

    sailbrd Well-Known Member

    Not saying that it can't work but I would really want to see a fuel pressure gauge that shows the rise in pressure with boost. So you want to see about 10-11 psi fuel pressure with 4 pounds of boost.
  5. Michael Evans

    Michael Evans a new project

    There is some depends.

    If you start out with seven pounds and running gasoline.

    I run nine pounds starting out (run gasoline)

    You want to run a boost reference fuel pressure regulator that will give you a one PSI raise in fuel pressure for every pound of boost.

    Running 10 pounds of boost, I wanted my regulator very sensitive and run a number six reference line.

    With even the touch of the throttle you can see the change in fuel pressure.
  6. Michael Evans

    Michael Evans a new project

    There is a difference between pressure and flow.

    A mechanical fuel pump can never be made (in Buicks case) to keep up with the demand of a Holley under a good amount of boost.

    It will run just fine in the pits (or your driveway) but when you but the carbuterator in demand, the flow will not be there.
  7. stubnosebrock

    stubnosebrock Well-Known Member

    What about mild boost numbers, say 4 to 5 psi? I ask because im thinking about going this route and have a RobbMc 500 horse pump, that I planned to have upgraded to the 1000 horse pump and thought that would be fine with the right regulator.
  8. jay3000

    jay3000 RIP 1-16-21

    I'm VERY interested to see how you did the hot side and exactly where you mounted the turbo. If you can't get to upload, please e-mail them to me.

    There is no way a mechanical fuel pump will produce 17psi necessary for 10psi of boost. Guarantee you wen't way lean..

    You absolutely cannot do a boosted application like that without a wideband O2.
  9. Michael Evans

    Michael Evans a new project

    Took all eight spark plugs out of the engine (to set the valves and get the converter bolts off ) to also find out why the EGT also was higher.

    It turns out by speeding the blower up richened not leaned the mixture like it should have.

    In the spring I will need to figure out how to get this 750 even leaner.

    A power valve change is needed ?
  10. hugger

    hugger Well-Known Member

    I would let the EGT or a wideband determine what the fuel curve needs to be, may just be too rich at low air speed giving the rich plug condition I assume you're eluding to, screw in air bleed carb I assume? If not thats a must on a blow thru, a healthy blow thru carb setup is a tough setup to tune for street duty, thats why fuel injection is so appealing in those situations, getting a carb to do two things at once is tough
  11. sailbrd

    sailbrd Well-Known Member

    Go figure. Mine went way lean with the new pulley. Guess we both have work to do this spring.

    Do not see where the power valve should be a problem because it is obviously opening. My usual problem with power valves is not opening at part throttle.
  12. Michael Evans

    Michael Evans a new project

    I have down jetted to something like (notes are out in the garage) 68 front, 86 rear.

    This is a carburator is up for blow-though with screw in bleeds. It is a 750-ban from Quickfuel.

    I had the tune pretty well then I changed the blower pulley (speeding up the charger).

    I was thinking speeding up the charge would insert more air ( it does) and lead the mixture, but in a blow though it must do the oppsite (in riching the mixture).

    When I pulled all eight plugs the were wet with fuel.
    Last edited: May 17, 2015
  13. hugger

    hugger Well-Known Member

    If they are wet id put some new needle and seats In just for kicks and giggles, cant see how that carb with that jetting would be be wetting plugs, and ive been doing good bit of reading on blow thru past few months , the QF and Demon shelf Blow Thru carbs dont get many strong reviews same with their E85 units , CSU entry level is $950 and from what im seeing is worth its weight in gold . But like I said if your wetting the plugs the carb has an issue other than its tune JMO
  14. Michael Evans

    Michael Evans a new project

    I turned the boost up last fall and as long as it only does 5400 RPMs everything it fine. But when I move the limiter up it blows the boost pipe off.
    The screw claims where only good for three pounds of boost and now with just over 10 pounds the T-clamps are failing to hold them together.

    Looking for other pipe clamping options.
  15. alan

    alan High-tech Dinosaur

    Are the ends of the tube beaded?
  16. sailbrd

    sailbrd Well-Known Member

    Good point. My welder took my pipes that did not have beaded ends (cut to fit) and just did a touch of weld every inch. Has held up for 9 pounds.

    I just went to 68/88's with a .076 PVRC. That is on the 650 BAN.

    Also had a little bog off the bottom. Changed the shooter's from .031 to .035 (AED tube style) and now nice and snappy when I hit. Will let you know what the WOT AFR's are this week. Always hard to get data on WOT because there is a whole lot of stuff happening then. Guess I need a go pro to record all the gauges.
  17. Michael Evans

    Michael Evans a new project

    The tubes have a single "bead" on the end. Will have to try the weld like you did to get more bite from the rubber connector.

    Will get the TIG weld out tomorrow and do this.

    Have 68 with 4.5 power valve in the primarys and 86s in the secondarys now is a rid on the rich side.

    No stumble at all just a bit rich.
  18. alan

    alan High-tech Dinosaur

    What are y'all using for head gaskets? I'm using .040 copper with O-rings, but I think cylinder pressure is getting into the cooling system. When I pressurized the cooling system with 16psi, it held. Not enough to cause a leak, I guess.
  19. sailbrd

    sailbrd Well-Known Member

    I just use a cometic MLS and that has held up well. Blew an "orange crush" gasket in just a few days when I first started running boost. Do not see where should have a problem with o-rings. I thought that was the gold standard.
  20. alan

    alan High-tech Dinosaur

    Me too! Maybe I'm just not doing something quite right.

    I'll double check it, pull it apart and do something different if needed.

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