30 DIC to 34 DICA conversion

Discussion in 'Rear-Engine Fiats' started by tomnj, Oct 16, 2018.

  1. tomnj

    tomnj Old fogie stogie

    Location:
    Scotch Plains, NJ
    I saw this conversion kit for 850's to upgrade the original 2bbl 30DIC weber to a 1bbl 34DICA carb. Anyone try this conversion? It looks like the choke and throttle linkage may be a bit tricky to attach. I would think this would provide bit more power.

    vbmbvnm.jpg
     
  2. kmead

    kmead True Classic

    Location:
    Michigan
    I doubt this would be an improvement, but one test would be certainly answer it.

    The sedan’s used a single barrel carb, they put out considerably less power (for a variety of reasons: cam, compression, valve diameter) so use that as a data point. It used a 30 ICF which is related but obviously smaller in diameter.
     
  3. NM850

    NM850 True Classic

    Location:
    Albuquerque NM
    I really can’t imagine that making more power. History tells us none of the tuners used a one barrel for more power.
     
  4. Jeff Stich

    Jeff Stich True Classic

    Location:
    Norco, CA
    That's not a 34DICA carb (which doesn't exist, btw), it's a 34ICH used on older VW's & such. I've got an old one that I considered doing this very same "conversion" with, just to see the result.

    weber34ich6.jpg

    Never got around to it after visualizing how, with an adapter plate fitted (as shown in the auction photo), the single barrel would basically just dump its fuel/air mix into the almost-twice-as-wide opening of the DIC's intake manifold. I considered perhaps using an opened-up 850 Sedan 30ICF manifold instead, but didn't have one on hand. So back on the shelf the 34ICH went...

    At $236+shipping, this Pierce Manifolds "kit" seems a bit lacking in the performance-to-dollar ratio. Stick with the 30DIC. ;)

    https://www.ebay.com/itm/362313324852
     
    Last edited: Oct 17, 2018
    kmead likes this.
  5. Jeff Stich

    Jeff Stich True Classic

    Location:
    Norco, CA
    Small-bore Fiat history tells us most of the tuners of the day did, in fact, use a one-barrel for more power - a larger one-barrel. Nardi, Giannini, Stanguellini, Siata, Abarth & probably a few I'm forgetting all did it on their Fiat 500, 600, 600D & 850-based engines as part of their various "tuner kit" offerings.

    I can't recall the 500's upgrade carb models, but I do know the 600/600D-based engines got the Weber 32IMPE &/or Solex 32PBIC, & 850-based variants got the Solex 34PBIC.
     
  6. NM850

    NM850 True Classic

    Location:
    Albuquerque NM
    My mistake. I knew that was the case with the older engines but I thought by the time the 850 came around the thinking had changed to going with larger two barrels such as the DCD.
     
  7. Jeff Stich

    Jeff Stich True Classic

    Location:
    Norco, CA
    The use of the 36DCD came along on the 850 Coupe-based Abarth OTS 1000 after its rather successful use on the 600D-based Abarth 850TC/1000TC Berlina Corsa engines. Sort of a natural progression, since the 2 engines were so similar spec-wise (ie: basic layout & head design).

    This was after Abarth had already toyed with the Solex 34PBIC on the earlier 850 Sedan-based OT850/OT1000 engines.
     
    NM850 likes this.

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