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Vacuum source

This is a discussion on Vacuum source within the General Help forums, part of the LSx Technical Help Section category; Hi folks! I've looked through the stickies and didn't see what I need....I installed a Gen III 6.0 (LQ4) truck ...

  1. #1
    Junior Member Wagonmaster's Avatar
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    Black Cherry
    1939 Chevrolet

    Question Vacuum source

    Hi folks! I've looked through the stickies and didn't see what I need....I installed a Gen III 6.0 (LQ4) truck engine into my 1939 Chevy and need a vacuum source for my power brake booster. Any ideas where to look for this?? These things don't have a lot of removable plugs like the "old" 350's and 327's, etc....
    Thanks for looking.
    Joe
    Last edited by Wagonmaster; 08-03-2008 at 07:24 AM. Reason: sp.

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    Track Whore 570SX's Avatar
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    look on the intake manifold. there are ports on it, on the back and up front by the throttle body. really any of them will suffice, but there is one on the back made specifically for that purpose.

    how did you not see them? if you didn't cap off the unused ones (which there must be, because '39 had no emissions standards), your idle would be really high if it would idle at all. or have you not started/run it yet?
    ~Jason
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    Junior Member Wagonmaster's Avatar
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    Black Cherry
    1939 Chevrolet

    Cool vacuum

    It runs, we drove it home, albeit w/o and power assist for the brakes. The computer is hunting for the missing O2 sensors. (no exhaust from headers to mufflers, yet..Considering that it's okay. There are NO plugs on this intake. The place on the back where trucks take vacuum (most are hydro-vac) is blocked off and no others in sight!! There are none used or unused, other than the one I spoke of. Remember, this isn't an LS1....

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    Slow'er'Ass Mr. Luos's Avatar
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    Can you get me a picture of where the intake is blocked off?

    That seems odd to me.

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    Junior Member Wagonmaster's Avatar
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    Black Cherry
    1939 Chevrolet

    Thumbs up

    http://www.chevyavalanchefanclub.com...html#msg717399

    This is the link to intake manifold replacement on the 6.0 Avalanche type engine (LQ4) that I have. The second photo shows where a power brake booster should hook up. The unit my engine came from had a hydro vac system, not a booster, so this fitting is blocked. I'm sure it can be removed ( I didn't see this when I first posted), but it is plastic, and I don't want to break or otherwise damage the intake. I plan to run it, since tests show that it makes big torques, and this is a street car, that will be a cruiser and sometime tow my Utility trailer and H-D.
    Thanks for your assist.

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    Track Whore 570SX's Avatar
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    yeah, i'm also wondering what you mean by "blocked off." also, there is a port on the top of the truck intake manifold, right in the middle. at least on ones i've seen.

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    Junior Member Wagonmaster's Avatar
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    Black Cherry
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    Blocked port

    Here is a pic of the intake and the port that I am talking about. There is a yellow circle that shows the port and the plug blocking it.

    [IMG][/IMG]

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    Veteran 0rion's Avatar
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    have you looked at that plug closely to see if you can tell how it's mounted in there? Sure would be nice if it was threaded but it's probably epoxied. Might have to hit a junk yard and find one with the open port there. If you're to that point I'd probably try to get that plug out one way or another before heading to the yard. Might get lucky and be able to get it out.

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    Junior Member Wagonmaster's Avatar
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    Black Cherry
    1939 Chevrolet

    Thumbs up Plug

    Good advice, thanks. I have ordered the factory plug for a vehicle with a power brake booster. When I get it, I will then know how it is attached. Short term, I have spliced the larger hose to a smaller one and attached it to a small port on the right side of the manifold at the top.
    Appreciate everyones advice and assistance.

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    Veteran 0rion's Avatar
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    good luck and keep us updated. Make sure you have good vacuum on that booster, not something you want to discover coming to a red light.

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    Junior Member Wagonmaster's Avatar
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    Black Cherry
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    Talking "Good" vacuum

    Indeed! For a small diameter line, the cars stops amazingly well...Not ready to go road racing yet, but hauls it down just fine![IMG][/IMG]

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    Veteran 0rion's Avatar
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    nice looking ride

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    Track Whore 570SX's Avatar
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    Quote Originally Posted by 0rion View Post
    good luck and keep us updated. Make sure you have good vacuum on that booster, not something you want to discover coming to a red light.
    another reason manual brakes are nice

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    Junior Member Wagonmaster's Avatar
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    Black Cherry
    1939 Chevrolet

    another reason manual brakes are nice
    Probably okay for your light weight. Not so for my sedan that will pull a trailer on occasion.

    I have found a factory power brake port, as indicated above. Now I have the fitting that goes there and will install it as soon as I can figure out how to remove the existing plug without damage. It would appear that it epoxys into place since there are no threads or grooves.

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    Veteran 0rion's Avatar
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    Quote Originally Posted by Wagonmaster View Post
    Probably okay for your light weight. Not so for my sedan that will pull a trailer on occasion.

    I have found a factory power brake port, as indicated above. Now I have the fitting that goes there and will install it as soon as I can figure out how to remove the existing plug without damage. It would appear that it epoxys into place since there are no threads or grooves.
    can you drill it out? Would have to take care not to get crap down into the intake and I'm not familiar with those intakes but if you could drill that plug out and not get crap inside it that may be your answer.

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    Junior Member Wagonmaster's Avatar
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    Black Cherry
    1939 Chevrolet

    Cool Drill??

    If I have to.... I hope I won't need to. The plug in the rear of the intake has GOT to be removed somwhow, I'm hoping for a better way. Someone with more experience on these "plastic" manifolds may have the right method.
    Thanks for your advice....

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    The Bandit Wesman's Avatar
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    Quote Originally Posted by Mr. Luos View Post
    Can you get me a picture of where the intake is blocked off?

    That seems odd to me.
    Its because the engine is out of an HD truck that has hydroboost hydraulic powered brakes instead of vacuum powered brakes. So the vacuum port on the manifold used for the brake booster is capped off from the factory.

  18. #18
    Junior Member Wagonmaster's Avatar
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    Black Cherry
    1939 Chevrolet

    Question Yes it is!

    Thanks...I get that, but the issue is how to remove it, and install the fitting for the vacuum booster. If you can help with this, please let me know!

    [IMG][/IMG]

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    Senior Member bigrondownhiller's Avatar
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    It looks like you could just cut off the end plug and slip a hose on there. Can you take a closer picture of the plug?

  20. #20
    Junior Member Wagonmaster's Avatar
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    Black Cherry
    1939 Chevrolet

    Plug

    Harder to see with the motor in the car...wish I'd taken a better pic when it was on the trailer, after we pulled it from the donor..... It isn't a "male" type plug. it is pretty much flush with the intake.

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