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Thread: ? Intake ? Individual runners to "Spider"

  1. #1
    Join Date
    Jun 2018
    Location
    MT View, HI
    Posts
    167
    My Cars
    '80 733i , '76 2002

    ? Intake ? Individual runners to "Spider"

    I have been fumbling with my running smoothly issues. I've searched but can only find questions about the 3.5 manifold, and it not being an upgrade. To bad, I have one.
    I have the 12/79 m30b32 with the early runners. Plenty of gaskets with a lot of potential vacuum leaks.
    Curious if there is any benefits to moving to the newer style 3.2 / 3.5 intake, like the 82's and later use. My thinking is the ease of finding injectors. I'm thinking I would probably have to use my throttle body (if thats possible).
    All opinions welcome.
    Mahalo

  2. #2
    Join Date
    Mar 2013
    Location
    USA
    Posts
    465
    My Cars
    E21/early e23/e34
    Hey James,

    Running issues are tricky on that car, I’d check the CTS (highly sensitive on that car) and the ICV or idle speed sensor (drivers side block, water hose going into it) also there is an adjustment to smooth out the idle on the throttle body, you can play with that if all the other sensors are good.

    Make sure your distributor vac hoses are routed correctly, there is a top and bottom on the throttle body (where they both go, I’ve seen some weird connections with the vacuum advance lines.

    Lots of back and forth about the pros vs cons about the difference on intake manifolds. I don't think it's really an upgrade to move to the 3.5 manifold, and if memory serves me right a real upgrade to the "tube" phlegm is to use e21 tubes, they're fatter and flow more air, plus it looks so much cooler in my opinion.

    Personally I don't thinks it's worth it, just make sure the gaskets are good, if your injectors are questionable send them out for service, (low impedance) so later Motronic won't work.

    Also, if your car still has the thermal reactors, junk those- On my 79 I took them off and am running M30B35 exhaust manifolds (use the downtubes from an e32) and a custom 2.5" (stock routing) into a Magnaflow, a resonator and a Vibrant stainless muffler and the car breathes MUCH better! It pulls better throughout the rpm range.

    Shoot me an email if any questions, I’ve finally got my car idling correctly and a really smooth idle, only real issue now is on the first start of the day in the morning I have to nurse the throttle for a few seconds but after that it’s all good.

    Last edited by kojo96; 03-24-2019 at 07:01 PM.

  3. #3
    Join Date
    Jun 2018
    Location
    MT View, HI
    Posts
    167
    My Cars
    '80 733i , '76 2002
    Thanks much Kojo,
    A ton of great info here. Sounds like the low impedance thing is a good reason to stick with what I got. The injectors are new. I'll save the intake dollars for more important items.
    I'll be looking a little harder at the CT sensor. My car has cat converters so I believe they're not reactors. It does have those ugly little ex manifolds where one feeds the next. I saved some manifolds and down pipes off an '89 633, the two outlet ones. Been waiting to do that until I get the 02 back on the road.
    I'm overall pretty happy with how this almost 40 year old car is running.
    I'll keep this thread updated.

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