Help Tuning CB Performance Dual 34 Solex Kit on a 72 Westy

[prairiedog]

I have a 72 Westy with 1700 that I bought as a non runner. Over the last few months my son and I have been slowing getting it running but we are now stuck and can't get the bus to run properly. Details and symptoms down below. I've also included a video. I've been through the search feature dozens of times and asked all my VW buddies and still uncertain as to what direction to head next. Any input appreciated!

Symptoms:
- Engine wants lots of timing like 28-33 degrees otherwise won't run
- Will start cold and idle low (650rpm) but once the advance comes up the engine races to 2200rpm and will not drop. Drives nicely and runs good but rpm won't come down.
- revving is not mechanical related... no hanging throttles, cables, etc.. all have been replaced and checked multiple times
- watch video you will notice that at idle the distributor timing is actually at 6-8 ATDC rather than 7 BTDC. This seems like a lot of swing for a SVDA.
- even a small adjustment to the throttle screw on either carb will cause the engine to fall too far and nearly stall our (or stall altogether). They are very finicky.

What we have done:
- New carb set dual solex 34 and is installed correctly.
- bench setup these carbs with correct throttle gaps (on/off choke)
no vacuum leaks known ... checked all the regular spots
- everything is plumbed and wired correctly
- yes valves all correct have verified TDB and timing marks etc..
- all new ignition system and using known working type 4 SVDA (VW 022-905-205S, Bosch 0231 170 093)
- 3000rpm timing is set to 28-32 and runs smooth
- following setup procedures so mixture screw is set as should be and carbs have been fully gone through now a few times to look for issues

Are these symptoms likely related to the distributor advance getting stuck? Should I try to rebuild the distributor? Are there other obvious things I can check or should be looking for with these symptoms? This is our first dual carb VW and proving to be a great learning experience

Video Link:
Link


Thanks for reading and all ideas welcomed! We want to get out and enjoy this bus soon!
_________________
1962 Beetle Deluxe - L380 (Bob) - sold
1972 Westfalia Project Pastel White (Gus the Crunchy Bus) - sold
1974 Westfalia Brilliant Orange (Vango)

[aeromech]

Try a different distributor. Even an 009. Barrow one to try.
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound

[Wildthings]

Time your engine at 28-30° BTDC @3800+ rpm, with the hose off and plugged.

Also do your carbs have bypass holes drilled in the throttle plates? If so they may need to be plugged.

[prairiedog]

Thanks for the suggestions. I'll give those both a try later tonight.
_________________
1962 Beetle Deluxe - L380 (Bob) - sold
1972 Westfalia Project Pastel White (Gus the Crunchy Bus) - sold
1974 Westfalia Brilliant Orange (Vango)

[mnwesty]

Do you have the plumbing that goes between each side? I can't tell from the videos if you do.
_________________
Brad Spear

1971 Karmann Ghia
1972 Westfalia

St. Charles, MN

[prairiedog]

Yes I have the balance tube between both manifolds hooked up. There are no known vacuum leaks in that circuit or the booster line either. Have tried spraying brake clean around the manifolds as well in case of poor seal but no luck. Will try adjusting timing properly again and see what happens.
_________________
1962 Beetle Deluxe - L380 (Bob) - sold
1972 Westfalia Project Pastel White (Gus the Crunchy Bus) - sold
1974 Westfalia Brilliant Orange (Vango)

[prairiedog]

Just a quick update on this issue. I put a good 009 in and initially the bus ran better and the timing behaved correctly as it should 28/30 at 3000rpm and settled down to around 8 degrees at idle. Engine warmed up and seemed fine. However, then took the bus for a short drive and very quickly noticed the idle raise back up to the 1800 range again like before and would not come back down. If you turn the bus off and restart it idles like a champ. I am going to block off the brake booster circuit completely and try again in the event there is some kind of catastrophic leak in that system.

However, I'm also wondering if there is some kind of tuning issue with the carburetors. For example once they move off the idle circuit they are getting stuck somehow. It is not related to anything mechanical (linkage, chokes, etc..) . This week I will call CB Performance in the event someone else has experienced a similar issue with these carbs.

Again, if any of these issues seem familiar to any of you please share your thoughts! Thanks!
_________________
1962 Beetle Deluxe - L380 (Bob) - sold
1972 Westfalia Project Pastel White (Gus the Crunchy Bus) - sold
1974 Westfalia Brilliant Orange (Vango)

[aeromech]

Could that new distributor be at fault? A couple weeks ago we found a distributor that got stuck advanced and the idle was way high. Suspected a bad spring inside the distributor. Replaced it with one from Bill Fowler. Problem is resolved.
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound

[prairiedog]

Thank you to everyone for their suggestions. I was able to eventually figure out that the initial setup on the new Brosol 34's is different than in the Bentley manual. I had set up the throttle blade gap to spec from the Bentley at 0.6mm but that is simply too much for these carbs. What would happen is having the throttle set this far open would basically eliminate the idle circuit and just try to run on the main jet. Upon the advice of an experience VW mechanic I closed the throttle adjustment fully then opened up and 1/4 turn at first contact on the stop and all my issues disappeared. The idle is still a bit low but I'll play with the mixture and timing a bit to get it up a bit more. Thanks for the suggestions as it got me moving in the right direction to solve my problems.
_________________
1962 Beetle Deluxe - L380 (Bob) - sold
1972 Westfalia Project Pastel White (Gus the Crunchy Bus) - sold
1974 Westfalia Brilliant Orange (Vango)