Page 2 of 2 FirstFirst 12
Results 11 to 15 of 15

Thread: Intake Manifold Leakage

  1. #11
    Join Date
    Jan 2005
    Location
    Vancouver Island B.C.
    Posts
    427

    Default

    Quote Originally Posted by T. Cotten View Post
    "Perfect" vacuum isn't achieveable, Dewey!

    But we can produce the same differential with pressure, as one atmosphere is just shy of 15psi.
    So 15psi is overkill, but it will display, with bubbles, any and all possible places for a vacuum leak.

    Even though the motor will never draw extreme vacuum, a tiny leak can still cause grief, or at very least a loss of performance.

    ....Cotten
    Aye...and what I was getting at is this statement..."as the negitive pressure in the manifold increases and approaches -14.7 psi".

    Since it says -14.7 psi...which is gauge pressure...that would be near 0 psi absolute...which like you say isn't achievable.

    Like you say pressurizing to 15 psi is overkill as a manifold is highly unlikely to see 15 psid. I know the importance of manifold leaks as I had a piston fry on my Sportster 35 plus years ago because of an air leak.

  2. #12
    Join Date
    Jun 2001
    Location
    Central Illinois, USA
    Posts
    3,296

    Default

    Once upon a time....

    I had built had built a '39 OHV for an associate, and had become quite quite familiar with it, allowed to ride it often.
    It was subsequently sold to a fellow who would return it to me for spring maintenance.

    One year, he said it "ran fine", but it just didn't seem to me to jump like the scalded dog I remembered.

    So a bubble-test showed just a little blister of tiny foam bubbles upon one inlet nipple rivet that took fifteen seconds or so to form.
    I sealed it with my 'secret sauce', retuned, and the owner announced that it ran "like a brand new motorcycle!"
    This leak only robbed performance, but many burnt motors brought to me "ran fine".

    No two leaks behave the same, except those that prevent the machine from running at all.

    ....Cotten
    AMCA #776
    Dumpster Diver's Motto: Seek,... and Ye Shall Find!

  3. #13
    Join Date
    Jan 2017
    Location
    Winfield,Ks.
    Posts
    5

    Default

    I have a question for Mr. Cotton.You stated in one of your posts that you might not get Viton O-rings to seal.Would you please expound on your theory has to why Viton O-rings might not seal.Viton FKM series O-rings are good for temperatures from approx. -40F to consistent temps.of 425F.They are as fuel proof as any seal produced and are a standard in the aviation industry.Presently I am fighting an intake leak on my freshly refurbished CH and have found the typical aftermarket O-rings to swell upon use indicating their instability when exposed to heat and fuels.Please reply to this question as I am extremely interested producing the best possible assembly with out the use of additional sealing compounds or other home brew methods.

  4. #14
    Join Date
    Jun 2001
    Location
    Central Illinois, USA
    Posts
    3,296

    Default

    I'm confused Pete!

    I have always endorsed JAMES viton O-rings wholeheartedly.
    (And yes, common O-rings are a lit fuse.)

    ....Cotten
    PS: The search function brings up nothing, so please link me to the discussion so I can clarify it.
    (If it was my previous post to this thread, I was referring to the stroker geometry problem.)
    Last edited by T. Cotten; 10-04-2017 at 09:19 AM.
    AMCA #776
    Dumpster Diver's Motto: Seek,... and Ye Shall Find!

  5. #15
    Join Date
    Jan 2017
    Location
    Winfield,Ks.
    Posts
    5

    Smile Viton O-Rings

    Quote Originally Posted by T. Cotten View Post
    I'm confused Pete!

    I have always endorsed JAMES viton O-rings wholeheartedly.
    (And yes, common O-rings are a lit fuse.)

    ....Cotten
    PS: The search function brings up nothing, so please link me to the discussion so I can clarify it.
    (If it was my previous post to this thread, I was referring to the stroker geometry problem.)
    T.Cotton,I'm sure my pondering came from an out of context interpretation of a posted reply to Bill Pedalino on 8-15-2017 in reference to Intake Manifold sealing problems common to both Sportsters and Shovel heads.I'm on a learning curve here and I'm just wanting gather as much experienced advice as possible to help me produce the best possible end product.Thank you for short but concise reply,it keeps me on track.Peter

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •