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Weber conversion manifold

Discussion in '"Stock" Alpine' started by smashbeat, Apr 9, 2021.

  1. smashbeat

    smashbeat Silver Level Sponsor

    Hi, I'm am in the process of replacing the solex of my series 4 with a new weber. I was told that the original intake manifold needs to be modified.
    Has anyone done that? Any advice?
  2. pruyter

    pruyter Donation Time

    You don't need to modify if you don't want, but....what some people have done is removing the bar which is in the middle of the input side (between the carburettor and the manifold).
    Even better is using a manifold which is used in the so called Webcon conversion which is developped by both SAOC in the UK and Webcon.
    Alpine Innovations in the UK is selling this manifold. The complete conversion regards both the manifold and the 32/36 DGV 5 A carburettor.


  3. Alpine 1789

    Alpine 1789 SAOCA President Platinum Level Sponsor

    Smashbeat: If you lay the Weber gasket on top of the original manifold, you will see what needs to be done to make it match the ports of the Weber. One port is likely larger than the other - depending on what Weber you have - and you can just use a sharpie to outline the opening in the gasket. As I recall (it has been years since I did this), I used a jig saw to cut the bar in the middle and then a rotary rasp to shave the opening to match the gasket. It was all pretty easy and didn't take long at all. I don't think the Weber came with a spacer, so I used the same process to open that up as well. You could also just open up the larger side of the intake a bit and not bother removing the bar. I don't think it makes any difference in how it performs.
  4. smashbeat

    smashbeat Silver Level Sponsor

    Unfortunately I forgot to buy the gasket between carb and manifold. Ordering it on Monday.
    I've seen a spacer used sometimes. Is that needed? I ordered from ss.
    Thanks Alex
  5. alpine_64

    alpine_64 Donation Time

    The spacer stops heat soak from the manifold to the carb. Your solex would have had one.. You can reuse it and open it up per the gasket to match the manifold and carb.
  6. smashbeat

    smashbeat Silver Level Sponsor

    I didn't even notice that the spacer was there. It was getting dark when I removed the solex... I saw it now and it's stuck. Hopefully I can remove it without breaking it
  7. Tim R

    Tim R Silver Level Sponsor

    To really improve the car you need to get the curved branch manifold with a 32/36 Weber and cold air induction kit as sold by Alpine Innovations (I have no connection with them but have two of their carb systems). This gives correct atomisation of the fuel and your car will not only return very high mpg it will perform like it never has before AND stay in tune. The 'Log' manifold tends to either give you puddles in the intake for 1 and 4 or lean running at 2 and 3.

    Tim R
    puff4 likes this.
  8. John W

    John W Diamond Level Sponsor

  9. alpine_64

    alpine_64 Donation Time


    Iirc there was an error in the design and you can't run a brake servo without having stalling issues?
  10. husky drvr

    husky drvr Platinum Level Sponsor

    IIRC, it's a problem with the PCV feeding into just the single runner for cylinder four. The single runner feed causes the mixture to go lean on that cylinder.
  11. puff4

    puff4 Gold Level Sponsor

    You can run the PCV into the plenum instead. There’s already a hole for it in the alpine Innovations manifold and that’s how I set mine up.
  12. alpine_64

    alpine_64 Donation Time

    Yes that is my understanding, the only solution i believe they offer is to plug the vac port.
    The stock s3 manifold doesnt have that issue as it takes vac from under the carb iirc. The siv has the draw from 1 runner but doesnt suffer the stalling issue
  13. husky drvr

    husky drvr Platinum Level Sponsor

    I don't know what the SS manifold is like but the curved Weber manifold that Alpine Innovations sell for their DGV conversion does not use the PCV, you fit a blanking plug into the threaded hole. On our Weber equipped cars we vent both the tappet chest and rocker cover to atmosphere on pipes that go down to the bottom of the engine in the transmission tunnel. The cars have been like this for a very long time with no problem. You can feel the air pulsing if you put your fingers to the pipes but there are no fumes or oil leaks caused by doing this. At one point we had a 'catch tank' intending to catch any oil that came out but it was not necessary.

    Tim R

    Sounds like they've made a change to the manifold since this posting.
  14. puff4

    puff4 Gold Level Sponsor

    In 2020 I installed the Alpine Innovations setup on my SV and here’s how I resolved the problem.

    - Brake servo goes on the #1 runner.
    - Plug the hole on the #4 runner. (This is where the PCV was originally designed to go, but it screws up #4 mixture.)
    - Remove the plug on the side of the plenum and use an angled fitting to install the PCV.

    This prevents any one cylinder from being affected by the PCV.

    [I should note that I’m not currently running a servo, so I also plugged the #1 runner hole.]


    Here’s a photo Jerome sent me in March, 2020. He said at that time that he’s supplying the new kits with the angled fitting included.

    Last edited: Apr 11, 2021
  15. alpine_64

    alpine_64 Donation Time


    My iirc.. Might be not recalling correctly.. The stall was pcv not booster.

    I am glad that someone put in the time to make a new part for our cars, based off the italian and NZ manifolds design...

    Its just a pity aesthetics were off the table.... While the manifold design is being determined by flow etc...all good...

    But i stand by the filter setup is absolutely horrid... Like a rice cooker atop the carb.. Or with the long breather attached looks like an original dr who Darlec ;)
  16. pruyter

    pruyter Donation Time

    I bought the Webcon conversion when nobody kwew about the fault installation place of the PCV. I found out by trial and error that the cause of stalling was caused by this PCV and as a consequence I removed the PCV and plugged the hole. Later on Tim Raymond in the UK was able to prove this design fault by using a rolling road. In the new design there is used a hole in the manifold in which the angled fitting is placed while in the manifold I have there is also a hole in this place which was plugged when I bought the conversion. This hole was ment to use if one wanted to connect a vacuum gauge which I did. But....this is a rather tiny hole and I guess that the hole in the new design is bigger and that rules out the possibility of fitting a vacuum gauge. Or....drill a new hole.


  17. puff4

    puff4 Gold Level Sponsor

    Why not just install the vacuum gauge in the plugged hole in the #4 runner? Seems a doddle to do.
  18. smashbeat

    smashbeat Silver Level Sponsor

    Seems like I need to do a lot of research at this point. And I opened a can of worms
    Can you buy just the manifold? Seems like this magic manifold is sold as a kit only with the weber carb. I already purchased the weber carb from ss and I only need a door stopper (the solex)
  19. puff4

    puff4 Gold Level Sponsor

    I would contact Jerome and ask. I can't see why not. He also may have "B-grade" manifolds at a lower price, which are just like the manifold above, but that aren't perfect... however they will perform just fine. Saves a few $$.
  20. pruyter

    pruyter Donation Time

    It is possible to plug in the vacuum gauge in the hole of the 4th runner, but the hole below the carburettor is by far the best place to plug in a vacuum gauge. The reading there should be best which is possible.



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