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Thread: Carbs & carb rebuilding

  1. #11
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    Transferred to consolidate same topic.

    guzyk Junior Member posted December 22, 2002 10:43 PM

    I have a 72 that has been converted to a single Weber and what appears to be a K&N filter.

    When I bought the vehicle in June 2002, there was no hose between the carb (air cleaner) and the crankase. A shop I went to a couple months ago said "you need a hose connecting them or outside air etc will enter the engine". The shop installed a red rubber hose.

    I recently noticed the air filter was very wet with oil (and it's not an oil bath filter) and the engine was burning a lot of oil. I assumed the carb was "sucking up the oil".



    Anyway, the other day I chopped the hose, folded each end over and tied them up (essentially sealing the plug on the crankcase and the one on the carb).

    Was this a stupid thing to do? What is the correct way to have a Weber/K&N setup on this type of motor?

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  3. #12
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    Anytime you go to an aftermarket system, you can count on it failing to provide ALL of the OE functions. The OE fuel system was designed to provide not just fuel, but the necessary EPA and performance considerations such as crankcase breathing. It's probable your first system failed to allow the crankcase to properly breath, thus sucking oil into the air intake; and your solution will now block crankcase breathing, increasing pressure until you do more serious damage. The replacement carb is not the problem, it's you now no longer have all of the original fuel system working. You can continue with the aftermarket carb but will have to reinstall or manufacture the now defunct parts of the original fuel and venting system.

  4. #13
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    I got a h30/31 carb for a 1600 sp engine. How do I tune it? It's not listed in the manuals at all.

  5. #14
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    Bentley, 5-4, Fig 5-26 & 5-27 show the carburetors and the chokes. Note the dual carb system of the '72> uses a central idling system off the left carb that then feeds the right. There is an excellent trouble-shooting chart, 5-1, Table b.

  6. #15
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    ok, so I pulled the carbs off, finding that there were no choke flaps for the ckokes to turn. So I found some and put them in. I have both carbs out still, and I've been doing some tests to them with a 12v motorcycle battery, hooking up the chokes and seeing how they work. And now I have some more questions.

    1)One of the flaps is just a little bit sticky if you close it up all the way, and sometimes needs just a bit of a touch to get it unstuck to open. Would the air intake possibly take care of this when the carb is actually mounted?

    2)The other carb's choke element will not open the flap completly from closed posistion (moves the flap about 30 degreas). The coil that contracts in the element when heated is a little lop sided, the center of the coil isn't the center of the element. I figured that it would still work, I just couldn't get the choke to go fully on if I want it to go off (and going off completly I guessed is important). Now maybe I should just get a new element, or maybe the diffrence is slight?

    3)Also wondering if anyone knew how long it is normal for one of the elements to heat up and contract the coil fully? It's about 4-5 min on mine, but I know it's designed so that when you open the throttle, a little arm kicks the choke open a little.

    4)How much does the air intake affect the posistioning of the flap? If it tends to open it a little or not that would be good to know.

    Thanks for your help on everything. Its great to have a place like this to have your questions answered.

    Alex

  7. #16
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    Obviously, they are not supposed to bind and that the flaps were missing is a strong indicator that the previous owner had screwed things up pretty good. The air intake valve, designed to insure warmed air during warm-up, has nothing to do with the choke -- it only determines where the supply air comes from.

    I'm not trying to be derogatory, but it appears you don't have a lot of experience in fuel systems and carbs and are fighting a previously screwed up system without a lot of the necessary tools & facilities. The Bentley kindly puts it, Section 2-5.4, page 23, "If you lack the skills, tools or a suitable workshop for rebuilding the carburetor, we suggest you leave such repairs to an Authorized VW Dealer or other qualified shop." I'm not going to tout the local dealer who probably hasn't seen a carb in 20 years, but you can get rebuilt carbs from vendors on this web-site or can have them rebuilt to the highest degree of quality by some of the antique car restoration vendors such as The Carb Doctor, in Nebo, NC. When you have multiple symptoms and causes, sometimes it's best to bite the bullet, do one right and eliminate it from the rest of the troubleshooting. Carbs can be pretty arbitrary and very difficult to correct.

  8. #17
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    Mar 2010
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    Default won't start after warm 74 westy dual carb

    Dear fellow Westy Owners:

    Running the risk of posting out of turn, I have a challenge. I have been pouring over these threads and I haven't found one that answers my question.

    My bus runs fine cold most of the time. Then, once in a while (and getting more frequent) the bus will not restart after a running for any length of time at operating temperature. I let it sit for a half hour, crank it and put the gas pedal to the floor and it will start. Then runs kinda rough for a few minutes. Then is OK.

    I have replaced fuel filter, air filter, spark plugs and wires, points, cap, rotor and coil and changed the oil with lucas oil conditioner all for good measure since I bought the bus with no service history.

    The problem existed before i changed out those parts.

    I checked the current to the carb solenoids and they click as per the test in the manual. The right butterfly valve seems to stick a little on visual inspection with the air filter piece removed. I hope thats it. But it looks intimidating to me to pull the carb, open it up and tune once i put it back on.

    Is there anything else I can do? If it were the fuel pump, wouldnt it crap out all the time, like never even start?

    Any ideas? Thanks a ton for having this site. Im glad to have found it!

    [Moderator note: Most probable is sticking or defective choke not resetting, Item 2, Table b. Bentley 3-5.1.]
    Last edited by Capt. Mike; 03-13-2010 at 09:59 AM. Reason: Moved to correct topic; email blocked

  9. #18
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    Mar 2010
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    Default carbs, timing, fule delivery

    Thanks Capt. Mike.

    Turns out with further testing, the fuel delivery to the carbs stops when the motor is hot. I pulled the gas inlet tube off the carb when cold, stuck the tube in a bottle and cranked the motor. There was about 2 oz of gas in the bottle after cranking for a few seconds. So I put the tube back on the carb cranked it up, drove around the neighborhood and then I let the bus idle in the driveway for about fifteen minutes or so until it died. Then I pulled the tube back off again, put it in the bottle and cranked it a few seconds again. This time, no fuel in the bottle. I ran it again this morning to the parts store to check out a temp gauge and got back in the bus to find it would not start. This time, I pulled the fuel to line to the carbs off the pump and put another tube to the bottle and cranked. Very little gas in the bottle.

    It seems that the fuel pump craps out at high or running temps. Vapor lock in the fuel line is not really likely to me unless its in the pump.

    I question wether or not the cooling flaps are open or closed. The bentley manual doesn't show how they are nested in home position or how they should look in the open position. There is however a very nice exploded iso graphic that shows all the parts. I can push on the cable mount on the flap rod downward and feel motion as well as pull on the cable from underneath and feel/hear the flaps move. i have also lubed the areas where the rod goes into the tin on left and right. I can not see where there are other hinges to lube. Perhaps something needs to be removed in order to do that.

    I have read that I have to pull the motor to get to the fuel pump. On inspection, it looks like I might be able to pull a hose off and i could get at it the upper mounting bolt. Is this true? My thinking is I could get a generic electric pump rather than pull the engine.

    I see the thermostat under the motor and it appears to have no change as the motor warms up. I fear that my engine is running way to hot because of the flap situation. That might be be the reason for the failure of the fuel pump. I have installed a new engine compartment seal completely around.

    Should I also clean the fins on the oil cooler? is there supposed to be air flowing out from the bottom of the oil cooler? When I put my finger under it while the motor is running, I feel no air.

    Am I on the right track? Is there any advise you can offer?

    Thank you for your assistance.

    Please advise.

    Brad

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