Who's running a Weber?

Discussion in 'Slant 6 Engines' started by Dantra, Jun 15, 2018.

  1. Dantra

    Dantra The Impostor "A"

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    I have a Super Six 2 2 barrel intake that I'm getting ready to stick on Hoopty and I'm really thinking the best route for a carb may be a Weber. I like the WK551 Jeep conversion but I'm not sure whether to go with the 32/36 , 36/36 or the 38/38

    I'm bone stoke with a 3 or the tree.. will be adding 2.25 exhaust

    Opinions for the best route to go with as little as tuning as possible? The ol truck doesn't go far so economy is not a factor.
     
  2. pishta

    pishta I know I'm right....

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    32/36 would work best. AMC guys use the 32/36 on the 258 and claim good results.
     
  3. Dantra

    Dantra The Impostor "A"

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    Thanks for the reply
    That was my initial thought.. but I read other stories that lead to some doubt. They were all old threads and thought I'd check and see.
     
    Last edited: Jun 18, 2018
  4. plymouth4onthefloor

    plymouth4onthefloor FABO Gold Member FABO Gold Member

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    I put a set of Webers on a customers 190SL, it's a fun to change the jets, but you need a dyno or a wideband lambdasond. There a hundreds
    of air jet, emulsion pipes and jet combinations! Be sure you have a good dealer near by you...
     
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    • Dantra

      Dantra The Impostor "A"

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      Went with a 38/38.. Now I wait
       
    • enigma57

      enigma57 Well-Known Member

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      Be sure and plumb a fuel pressure regulator into your fuel line. Weber needle and seat requires max 3-1/2 PSI. Some will tolerate up to 4-1/2 PSI when new, but will eventually wear down and and flood carburettor.

      Most 38 DGAS (water choke) and DGES (electric choke) carbs come jetted for 3.0 litre engine. Should be close enough for baseline jetting with 3.7 litre 225 slant 6. Original 38 DGAS had 27mm chokes (main venturii). Some of the newer ones have 30mm chokes but come with same (too lean) jetting, so you may need to bump idle (slow running) jets from 45 to 55. Idle (slow running) circuit on Webers run carb to around 2,500 RPMs before transitioning to main circuit. If main circuit is lean following idle jet change, leave 145 main jets in place and swap out 185 air correctors for 175s. That should get you pretty close......

      http://www.lcengineering.com/LCTechPages/pdf/38DGAS.pdf

      Best regards,

      Harry

      P.S. >>> If you keep about 4" long stub of original 2-1/4" OD headpipe where it bolts up to exhaust manifold, 2-1/2" OD tubing fits over 2-1/4" nicely. Just slip 2-1/2" tubing over stub about an inch and weld it up. Run 2-1/2" single exhaust with good 2-1/2" turbo style muffler and you are good to go.
       
      Last edited: Jul 12, 2018 at 12:46 AM
    • Dantra

      Dantra The Impostor "A"

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      Appreciate the reply...

      I have a regulator coming and plan to run right around 2lbs of pressure. From what I've read, that should be plenty enough for a good starting point and the manual states no more than 3.

      The kit that I ordered is a Jeep kit and has been jetted for the 258. So my baselines are a little different than what you described but the info you added will be helpful.

      I was planning a 2.25 but may consider the 2.5. I'm shooting for something on the quiet side and a turbo might sound pretty nice.

      Thanks again!
       
    • enigma57

      enigma57 Well-Known Member

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      Sounds good. Be sure and get a fuel pressure gauge so you can see what you have there through entire operating range. I would suggest beginning at 3.0 PSI, as pressure at needle seat and fuel level in fuel bowl will fluctuate depending on load and RPMs as you increase / decrease engine speed. Even more so if you retain the mechanical fuel pump.

      Its a balancing act. On the one hand, you don't want to exceed max fuel pressure of 3-1/2 PSI but on the other hand, you don't want pressure to drop too low when you open the throttle a lot either, as float level and resulting fuel level in float bowl are critical to proper operation with Weber carbs. The saving grace with the 38 DGAS or DGES is that it is fitted with F-50 emulsion tubes and they are pretty much 'neutral' from top to bottom as far as diameter of tube and spacing & sizing of holes.

      Good luck with your new carb. Look forward to hearing how it works out on your engine.

      Best regards,

      Harry