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vaccuum issues!!!!!!!!!!!!!!!

This is a discussion on vaccuum issues!!!!!!!!!!!!!!! within the Internal Engine forums, part of the LSx Technical Help Section category; Ok here is my set up 408 lq9, stage 3 243 heads, cam is a 248/254 .618/.622 113lsa, fast 92/92. ...

  1. #1
    408 ci + 4000 stall = fun lancesT/A's Avatar
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    vaccuum issues!!!!!!!!!!!!!!!

    Ok here is my set up 408 lq9, stage 3 243 heads, cam is a 248/254 .618/.622 113lsa, fast 92/92. 42lb injectors. i have almost no vaccuum. the car is a yr long project and a rather expensive one..... if anyone has any hints as to why i have very little vaccuum let me know cuz im scratching my head

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    Moderator Cutlass's Avatar
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    because your camshaft is huge

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    408 ci + 4000 stall = fun lancesT/A's Avatar
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    ya but plenty ppl run bigger well what do i do to get vaccuum up??

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    cutting and welding mark21742's Avatar
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    hugger orange
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    Vacuum pump or ditch the booster and go manual brakes...I take it that's why you need more vacuum.
    Yes your cam is why you don't have any vacuum

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    408 ci + 4000 stall = fun lancesT/A's Avatar
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    even at idle i would think i would atleast at idle.. no?

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    cutting and welding mark21742's Avatar
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    hugger orange
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    Nope

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    King 0f n00bz shady milkman's Avatar
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    Quote Originally Posted by lancesT/A View Post
    even at idle i would think i would atleast at idle.. no?
    Quote Originally Posted by mark21742 View Post
    Nope
    i love the straight to the point


    i would personally lance (i hope that is your name) run a booster to keep with the dive-ability of the car

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    Senior Member bigrondownhiller's Avatar
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    You could also go with a hydro boost for the brakes.

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    408 ci + 4000 stall = fun lancesT/A's Avatar
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    ya well right now it wont idle and once u get above 3500 rpms it acts fine i know the cam is robbing some vaccuum but im not sure its not losing it thru the intake im gonna put a stock one on and see if i hold vaccuum

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    Senior Member bigrondownhiller's Avatar
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    Sounds like you have a vacuum leak somewhere.

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    Smiles for 9.5 Years cammed goat's Avatar
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    Quote Originally Posted by Cutlass View Post
    because your camshaft is huge

  12. #12
    Smiles for 9.5 Years cammed goat's Avatar
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    I have read in GMHTP that a vacuum booster would be required for vehicles running large cams.

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    Moderator Cutlass's Avatar
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    To get a big cam to idle better, sometimes you need to crank the ignition timing way up.

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    408 ci + 4000 stall = fun lancesT/A's Avatar
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    i have to mention the advancing the timing to my tuner

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    cutting and welding mark21742's Avatar
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    Quote Originally Posted by lancesT/A View Post
    i have to mention the advancing the timing to my tuner
    I ended up adding about 5 degrees advance to my idle timing to get mine to smooth out and drop. 238/242 idles pretty smooth at 990 rpms and will probly be dropping down alittle more after i'm finished all the other tuning

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    can you reconfigure the air pump to supply vacuum for the brake booster,using a storage tank.

  17. #17
    cutting and welding mark21742's Avatar
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    I think its Honda that is now using electronic assist brakes and steering, I take it that its electic pumps instead of belt driven... Just a thought

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    408 ci + 4000 stall = fun lancesT/A's Avatar
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    i have to consider but first i need to find out if i have a vaccuum leak ?.. il prolly get some vaccuum assistance regardless

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