Results 1 to 5 of 5

Thread: Intake manifold alignment

Discussions of MG Sports Cars

  1. #1
    Freshman Member steve00136's Avatar
    Join Date
    Dec 2019
    Location
    Nottingham UK
    Posts
    4
    Blog Entries
    1
    Thanks Thanks Given 
    0
    Thanks Thanks Received 
    0
    Thanked in
    0 Posts

    Intake manifold alignment

    Having recently swopped carburettors I took the opportunity to check how well the joints between the carb and cylinder head were mating.
    I noticed a pronounced ridge of about 3mm where the inlet manifold mates onto the head. This may only affect performance at high revs - but it is not ideal.
    It seemed as if the manifold needed lifting a little which would be a quick and simple solution to centre the manifold to the head. So I slotted the inlet manifold mounting hole and repositioned the manifold which cured the problem.
    Can't say I've noticed any improvement in performance but it's satisfying that I know these parts are properly aligned and fitted correctly.
    1975 MGB Roadster
    Nottingham UK
    blog: mgb.tips

  2. #2
    Moderator Mickey Richaud's Avatar
    Join Date
    Mar 2003
    Location
    Townsend, Tennessee
    Posts
    14,919
    Thanks Thanks Given 
    1
    Thanks Thanks Received 
    27
    Thanked in
    27 Posts

    Re: Intake manifold alignment

    As long as the ports on the manifold and the head are aligned, all should be well. But as you say, having things lined up does make one feel better!


    Mickey
    "There are three kinds of men. One who learns by readin'. The few who learn by observation. The rest of them have to pee on that electric fence for themselves." Will Rogers
    Mickey Richaud - '73 MGB, '69 MGB GT/V6 (both SOLD! ); Victor TF 1800; '03 Jaguar XK8
    ------------------------------------------------------------

  3. #3
    Jedi Hopeful
    Join Date
    Jul 2018
    Location
    Austin TEXAS
    Posts
    145
    Thanks Thanks Given 
    0
    Thanks Thanks Received 
    6
    Thanked in
    6 Posts

    Re: Intake manifold alignment

    Never even occured to me that this COULD be wrong - I just always assumed they were designed to line up. I have mine off now to do some cleaning and paint touchup on the engine, so when I reassemble I will be sure to check this...

  4. #4
    Great Pumpkin DrEntropy's Avatar
    Join Date
    Sep 2005
    Location
    Elsinore, DK
    Posts
    33,200
    Thanks Thanks Given 
    36
    Thanks Thanks Received 
    73
    Thanked in
    72 Posts

    Re: Intake manifold alignment

    Mass production takes into account a certain amount of "slop tolerance." That leaves it up to us as caretakers, to correct and finesse things to their optimum. The intake and exhaust runners in most MGB heads are left as rough-cast ports. It pays to clean them up and check the alignment with the manifolds. The "old ways" treatment for intake ports was to polish to a mirror finish, unfortunately that lead to a laminar flow issue and less efficiency. An 80-grit finish after cleaning all the sharp points and rough parts of the casting and aligning the manifolds to the head will noticeably smooth out the running of the engine. Worth doing if the head is coming off.
    '64 MGB, '67 Lotus Elan S-3 DHC,'69 Lotus Elan +2
    '78 Alfa Romeo Spider-undergoing surgery: O=\*/=O
    '84 300D Turbo-"Diesela"-Now my Daily: Oo|≣|oO
    '02 Toyota Camry- SWMBO's 'new-to-her' Daily. <sigh>
    Chaos & Mayhem PTY, LTD..C.I.O. & Floor Sweepervisor

  5. #5
    Jedi Knight billspohn's Avatar
    Join Date
    Mar 2006
    Location
    BC
    Posts
    848
    Thanks Thanks Given 
    0
    Thanks Thanks Received 
    1
    Thanked in
    1 Post

    Re: Intake manifold alignment

    Doesn't matter at all on a street car.

    Standard procedure on race cars to index the manifolds and install roll pins to ensure automatically perfect fitment.
    Current clutter: 1957 MGA-Jamaican, 1958 MGA Twincam (race car), 1962 MGA Deluxe Coupe, 1971 Jensen Interceptor
    2009 Pontiac Solstice GXP Coupe, 2007 BMW Z4M coupe Recently departed: 1965 Jensen CV-8, 1969 MGC roadster, 1969 Lamborghini Islero S

Bookmarks

Posting Permissions

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