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Thread: B&M 174 no wine

  1. #1
    Junior SCH Member
    Join Date
    Jun 2010
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    2

    B&M 174 no wine

    I have a 74 el camino with a big block in it. Its a 402 stroker with a 174 B&M blower on it. It has an 800 dual feed carb, 454 oval port heads, 7 to 1 compression, and its cammed (not sure of the lift). I bought it a year ago not knowing to much about cars, thought this would be a good start! I've talked to all my car buddies and they all dont think the super charger is working because it dosnt wine. ive heard its just the belt that makes the wining noise and after a while it wont wine anymore but im not sure.
    I also dont know what type of oil to use.
    And i heard that the heads i have on (the oval ports) aren't the best for a supercharged engine.
    If someone could help me out it would be greatly appreciated!

  2. #2
    SCH Member
    Join Date
    Nov 2009
    Location
    Lawrence, KS
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    50
    for roots blowers in general:

    cog belts whine as air tries to escape the teeth-don't know any reason why it would ever stop whining.

    People have drilled a small hole in the middle of every other valley to allow air to get out and lower the noise.

    V and multiribs shouldn't make much noise, so if that's what your running then you're most likely hearing the rotor noise.

    If rotor noise diminishes over time then the rotor clearances may be opening up or need new telflon on the tips (if your model has them) Have your boost gauge readings gone down over time?

    As far as oval ports being the wrong heads for blower- it depends on the flow of the blower, boost, and cam size. Rectangular port heads are generally too big for your average car guy to need, but they may allow more airflow into the engine under boost (remember-boost is how much air is NOT being let into the motor by restrictive throttle body, intake, cam, heads, valves or combo of all)

    so you may get more flow into the motor and lower boost number indicated, but you dont need them unless a head change is in the works.


    rick
    Last edited by 69fury; 07-05-2010 at 01:43 AM.

  3. #3
    Junior SCH Member
    Join Date
    Jun 2010
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    2
    Alright yeah i have a v belt so that dose clear that up haha thank you.
    i dont have a boost gage... so im not even sure if its making any boost at all...
    so with the heads. would porting them do me any good? or is it better to just keep them stock? and me having the stock heads and a bigger cam, would that be throwing off the air flow? maybe dogging it a little?

  4. #4
    SCH Member
    Join Date
    Nov 2009
    Location
    Lawrence, KS
    Posts
    50
    if it's gotten noticibly more quiet, then get a boost gauge and check to see if you're making any. Is it lower on performance? you may need to get the rotors restripped.

    In today's age- it's generally cheaper to buy better heads than to spend money having them ported. Unless you really dig it, head porting is not glamorous at all. IT IS A REALLY DIRTY MESSY PAIN IN THE ***. (ask me how i know this-metal gets everywhere..)

    shop around for a good set of used aluminum heads, have the blower restripped or swap for a bigger one, stab in a more modern cam if yours is old school. if the heads are good but the cam is mild then a new cam may be where you get some gain, but i doubt you're overpowering those heads with a small roots.

    At very least if you've noticed performance loss, check w/ boost gauge then pull it down and use a feeler gauge to check the clearances.

    That way you know if you're looking at a refresh or time to upgrade....

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