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    1. #1
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      DCOE recommendations

      Hey guys,

      So I'm planning on bolting up a set of DCOE's to my stock B18, a little tired but with reasonable compression across all four. I have the R sport replica long runner intake manifolds (I realize some fender modification will be needed) and an IPD header. My question is do I go with 40's or 45's. My thought was to just go with the 45's and choke them down as I plan on building a B20 in the future and this would allow for some expansion. I had good success in my aircooled days choking down 44 IDF's to run on 1600-1800cc flat fours so am I correct in assuming that this shouldn't be much different?

      Also, I need some jetting guidelines. What chokes and jets would I want to baseline with for a stock B18 assuming I'm going with 45's (if you think 40's are better then specify for 40's)?

      This isn't a debate whether SU's or Weber's are better for my application, that's not what I'm getting at, I'm bolting the Weber's on regardless. Any help would be much appreciated.

      Also, I'm considering freshening up the B18 a little bit. Is there anything relatively cost effective to spruce the old lump up while I pull off the cylinder head for inspection? Maybe take a little off for more compression? New piston rings?

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    3. #2
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      Check the piston height above the deck to insure that you have the appropriate quench band clearance. Will help with suppressing detonation. With that done you can then check the clearance volumes on the head and make an informed decision about the compression ratio. Does the engine have inserts on the exhaust seats to deal with unleaded fuel? If not, that would be a good thing to add while the head is off. You could also get a multi angle valve seat cut if you can find a good machine shop! Are the valve guides OK?

      All this starts to result in creeping $. If you are thinking of doing a B20 transplant, perhaps better to save the money for the B20 and just soldier on with the B18 without investing $.

      There is a thread on this forum that includes comments from Mr. S. on the appropriate piston height in the block and machining the pistons to get identical heights.

    4. #3
      Moderator Phil Singher's Avatar
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      By all means go with the 45s, especially if you're planning on building a B20 later on.

      Default chokes are 36mm, but I think you'll do much better with 32s.

      Default F16 emulsion tubes will get you by for now.

      Default 55F8 low-speed jets could work. 50F8 might be better -- whichever ones give you fastest / smoothest idle with the idle mix needles 2 1/2 turns of their seats. Stick with F8 or you'll be thoroughly confused.

      Default 160 main jets will be much too large -- something in the 125 - 135 range should work for the B18, but you'll have to experiment. Add 40 or 45 to the main jet size for the air correctors.

      That should get you driving...

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    6. #4
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      Quote Originally Posted by Phil Singher View Post
      By all means go with the 45s, especially if you're planning on building a B20 later on.

      Default chokes are 36mm, but I think you'll do much better with 32s.

      Default F16 emulsion tubes will get you by for now.

      Default 55F8 low-speed jets could work. 50F8 might be better -- whichever ones give you fastest / smoothest idle with the idle mix needles 2 1/2 turns of their seats. Stick with F8 or you'll be thoroughly confused.

      Default 160 main jets will be much too large -- something in the 125 - 135 range should work for the B18, but you'll have to experiment. Add 40 or 45 to the main jet size for the air correctors.

      That should get you driving...
      Thank you Phil, exactly what I was looking for

      I just found out a friend has a set boxed up for a 2002 project that has long since stalled. I wonder if I can coax him into letting me borrow them to keep them in "working order" to "test" this setup on my car

    7. #5
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      ahhhh.. i think this is the thread I was looking for. I'm gonna go with a pair of 40s on my b18 with a slightly decked head with a stahl header and a simmons sport exhaust.

      I'll try the Jetting that Phil suggests above as a starting point.

    8. #6
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      The jetting suggested is for 45's, if you go with 40's your jet setup will be different based on your venturi size.

    9. #7
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      OK i found some info on the baseline setup for the 40s with a D cam B18 (which I'm told is pretty similar to the K cam):

      Choke: 36
      Aux Venturi: 4.5
      Main Jet: 130
      Idle Jet: 55F8
      Emulsion Tube: F2
      Air Corrector: 175
      Pump Jet: 40
      Back Bleed: 40
      Needle Valve: 200
      Float Level: 7

    10. #8
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      Any updates. I have a set of DCOE40s waiting to go on my B18. Would be good if you posted your jetting as my setup is similar.


      Sent from my iPad using Tapatalk

    11. #9
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      After all this time I'm still not up and running, had another kid and slowed my progress way down. Engine is done rest of the car not so much.


    12. #10
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      Engine looks great. Even the fan looks like new! Keep updating on progress.


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    13. #11
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      Bringing this thread back from the dead as I'm getting close to running this engine finally. I've cross posted this on various Facebook group pages as well to get some input from the Swedish tuners as well.

      I'm preparing to break in my metric 8 bolt B20 big bore 2130cc engine with stage two cylinder head (injected head with bigger intake valves, worked over combustion chamber and revised exhaust ports, and single high rev springs), 9.5 compression, KG Trimming KG10 camshaft, 123 programmable distributor and Weber 45 DCOE's on long runner intake manifolds. This is mated to an M41, stock ratio rear end, with 205/60 tires. Using standard NGK BP6HS plugs with factory gaps and Bosch blue coil, I may use my my Bosch distributor for break in until I completely understand how to use the 123 distributor. I also set initial lash on both intake and exhaust side to .018 since I really don't know what this engine should be set to and the head will be getting torqued again after break in.

      The idea for this engine and car is reasonable daily driver characteristics on crappy California 91 pump gas. The car will be used for a moderate 40 minute round trip commute a couple days a week and eventually longer weekend tours to southern and northern California, perhaps even a tour up 395 when I feel comfortable enough with the car.

      As far as the DCOE's are concerned these came from the off the shelf conversion kit but being as I'm a Redline Weber dealer I have an infinite amount of parts at my disposal. The standard conversion specifications are based on a compromise of installing this kit on either a standard B18 or B20 which obviously this is slightly more in every respect. Standard specs are as follows: Main Venturi 36mm, Secondary Venturi 4.5mm, Emulsion Tube F16, Main Jet 145, Air Correction 155, Idle F60/8. It's also recommend to set floats to 14mm drop with 2mm needle set. Standard air horns are 2.5 inches but I'll be installing 1.5 inch horns for daily use with an ITG filter ( I also have a set of 5 inch horns with screens but I would imagine using these even for fun would require a rejet). I have a 4 gas analyzer at my shop ;o)

      Right off the bat I can see some issues with the base setup but inputs would be greatly appreciated.

    14. #12
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      Engine: 2130cc B20
      Camshaft: KG10
      Compression: 9.4:1
      Timing set to 12 degrees at 900 RPM
      Spark Plugs: BP6HS

      Choke: 37
      Aux Venturi: 4.5
      Main Jet: 150
      Idle Jet: 60F8
      Emulsion Tube: F2
      Air Corrector: 190
      Needle Valve: 200
      Float Level: 14mm from carb top
      Fuel Pressure: 2-2.5 psi

      Just checked my plugs after 100 miles and golden brown so I know I'm just about perfect, still need to throw a wideband on it as I get a slight lean pop through the carbs when cold or at cruise tip in.

      *** Remember California 91 octane has quite a bit of ethanol in it and old jetting charts don't take this into account. Some people say increase idle/main jetting by 5-10% to compensate for this lean condition.
      Last edited by R32rennsport; 09-27-2019 at 03:45 PM. Reason: add info

    15. #13
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      Video from a few months ago after break in. I've made some slight jetting changes since my last post but nothing drastic. I'm pulling the cylinder head in the near future to take care of a leaking head gasket and I'm going to move down in venturi size for a little better bottom end response when I pull the carbs off. The bottom picture shows the base plate for the ITG filter which has to be cut from a blank, as well as the custom threaded support I made in lieu of an R sport brace. In the engine bay picture notice the center pull throttle cable setup, extremely easy to setup and very smooth, best of all no throttle changes over bumps or with engine torque that you get with the standard rod setup.

      https://youtu.be/btL9mVxaVIg



      Last edited by R32rennsport; 03-05-2020 at 05:35 PM.

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