VW carb switch, 34 to 30

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ericheath
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Re: VW carb switch, 34 to 30

Post #16 by ericheath » Thu Apr 02, 2020 3:30 pm

Temperature and humidity combine as factors. With 100% humidity you can have icing at 60 degrees.

I’ve been reading the single carb builds as people share them. I haven’t done one, so I can’t say, but I think there are a lot of factors and many variables. I have noticed one thing stood out as seeming to give a higher chance at success, it’s the ones who’ve used a larger plenum (vw type 4 I think) and although it is made for a 2bbl, they add a two-into-one adapter between the carb and vw plenum.

There is one guy who also successfully put on a four barrel sticking up thru the false tank with a roots blower looking scoop on it.

To me, what stands out on those as opposed to the log style is the fuel has a decent drop down before going to each cylinder. I don’t know if that’s a factor in their success or not, just an observation.

Another one that stands out as really different is using just one inch ID pipes for the runners. I have watched videos of it and it sure seems to scoot. Big runners may help at wot, but who rides at wot?
Whatever I suggest here should be given ample time for a moderator to delicately correct. I apologize in advance.
77 WING, 1200 engine with 77 heads, cams, gl1100 foot pegs, Magna V65 front end, 764A carbs, [-gone Suzuki M109 monoshock--, replaced with gl1100 shocks] gl 1200 swing arm, gl1500 final drive, wheel and rear brakes Valkyrie seat, Meanstreak tank, Sportster pipes, Power Arc ignition off crank.
77 Wing. black
83 Wing, in pieces
"Continuing education is important even if the subject matter is fairly useless (as in this case)."---Greg Foresi

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taunusrainer
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Re: VW carb switch, 34 to 30

Post #17 by taunusrainer » Wed Apr 08, 2020 4:12 pm

Very interesting icing diagram. If one builds a 4to1 intake manifold, icing will occur unless it is not heated by either engine oil or coolant. When I did tests on homemade manifolds long ago, the icing thing caused me to give up. Later I grabbed a used CC products manifold (coolant heated) and went on. Weber progressive 28/36 DCD was the most successful choice, but never came close to stock carbs. It ran ok, nothing more nothing less. Fuel economy was also an issue. Maybe I never found the right combination of venturis and jetting...
1976 GL1000 test mule
1977 GL1000 in parts, rebuild in progress
1980 GL1100 Interstate

1969 Ford 17m 2.3V6
1976 Ford Cortina 2.3V6 (Propane)
1990 Mustang 5.0 7up conv.
1994 Volkswagen Polo (Propane)

JohnB1953
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Re: VW carb switch, 34 to 30

Post #18 by JohnB1953 » Wed May 13, 2020 8:07 pm

I too have thought about using a PICT30 Solex carb . I have a little experience in that I have a VW trike that I built in 2008. It had a 1600 dual port with a pict 34 carb. It was ok but could be a bit of a pain to tune. This last winter I rebuilt a 1641 single port with a remanufactured PICT 30 carb. What a difference in motors better power much smoother. That got me thinking I bought a light roll over 1981 GL1100 trike and rebuilt it for my son in 2015. The wing had carb issues from sitting and I was able to buy a nice low mileage 1100 for less time and money so I have the old GL left over. I have always thought a single carb would be worth looking into, so I really like this thread. I also found out the hard way that those EMPI and other cheep china carbs are NO GOOD. I have another stock PICT30 I am going to send out to Volksbitz and have it remanufactured . I need to do a little more research on manifold construction.I don't know why this carb wouldn't work as my VW is 1641 cc and around 50 or so hp, and like I said it runs great. So I hope to hang around here and learn. Thanks John B

ob1quixote
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Re: VW carb switch, 34 to 30

Post #19 by ob1quixote » Thu May 21, 2020 9:46 am

Had my wing out for a trip to TN to ride done mountain twisties. 26 mpg when spanking it on the slab, 30-32 mpg when running in the 65-70 range. Rock solid 900 rpm idle when fully warm.
1979 GL1000
2001 DRZ400
1983 CR480
And a few late '60's - early '70's British thumpers

ob1quixote
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Re: VW carb switch, 34 to 30

Post #20 by ob1quixote » Thu May 21, 2020 9:47 am

Headed for a BRP tour last weekend of the month!
1979 GL1000
2001 DRZ400
1983 CR480
And a few late '60's - early '70's British thumpers


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