vacuum reading on an lt1?
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5.0 and 5.7 Discussion, vacuum reading on an lt1? in Cadillac Engine Technical Discussion; What should the vacuum reading be for an lt1? mine was 16-17 but i am going to try to measure ...
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    ocjmakaveli's Avatar
    ocjmakaveli is offline Cadillac Owners Enthusiast
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    vacuum reading on an lt1?

    What should the vacuum reading be for an lt1?

    mine was 16-17 but i am going to try to measure it in a couple different spots tomorrow

    I'm just incredibly glad i can do burnouts again now that my broken exhaust bolt has been fixed it was a PITA but i got it done

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    N0DIH's Avatar
    N0DIH is offline Cadillac Owners Master
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    Re: vacuum reading on an lt1?

    Cool! Glad to hear it. If I measure at the vacuum line to the Opti after the check valve, I get 15inches. No more, no less. I was expecting more. Maybe there is some restriction there. But with no "load" on the line, I am guessing that is what I get before it too. Sorta like Kirchoffs law for electronics applys to vacuum lines!

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    ocjmakaveli's Avatar
    ocjmakaveli is offline Cadillac Owners Enthusiast
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    Re: vacuum reading on an lt1?

    Quote Originally Posted by N0DIH
    Cool! Glad to hear it. If I measure at the vacuum line to the Opti after the check valve, I get 15inches. No more, no less. I was expecting more. Maybe there is some restriction there. But with no "load" on the line, I am guessing that is what I get before it too. Sorta like Kirchoffs law for electronics applys to vacuum lines!
    Actually what just occured to me was that my vacuum manual says that the rpm should be 100-200 above normal and i forgot to do that so i got 16 at idle man my head is full of air sometimes....

    I'm going to try it and see if it gets a little higher which i think it should be btw nodih how many miles does your engine have?

    try to rev it slightly nodih maybe thats why it was a little low

    I tried the hose that goes on top of the fuel regulator right next to the egr valve. I've heard of people using the heater/a/c vacuum hose ont he pass. side its a small hose also. The other thing is that i didnt use a tee which i should i only unplugged the fuel line and measured the vacuum at idle i guess live and learn. Most people say to measure directly from the manifold so im going to try that but i have to remove the big homeplate on top of it and try to plug the hole probably with a hockey puck and then try to measure that way from one of the outlets on the manifold.I sincerely doubt that my engine would be running the way it is if one of my hoses were disconnected or if the manifold gasket was bad etc.


    My engine runs just like new now i missed that rev on that 1-2 shift just like it used to have it revs like crazy now right from that start line.

    Best of all i dont hear a hissing sound on the pass. side like i did before there was major air being sucked in and on top of that the gasket itself looked damaged/black on the hole where the bolt broke i guess from so much air in and out the gasket turned black in that area.The hissing was pretty bad too now i only hear a slight clicking but many people say its normal because the lt1 has very thin valve covers allowing the noise to be heard.its not a tick only the sound of the valves working

    I have an annoying smell right now but im hoping its the damn exhaust flange gasket i put on i cant see or feel anything close to the exhaust that could be burning but i do smell it and every once in a while theres a little smoke that comes out behind the manifold somewhere but i can only see it with the hood open ill give it a few days if not ill have it checked out at an exhaust shop.

    Oh yeah i finally got around to finishing the spark plug change i only did the driver side a month ago and put off the pass. side because it was damn near impossible and jacking the car up to do it from the wheel wells seemed like a PITA it was remarkably easy with the exhaust manifold off.

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