1971 bus won't idle below 1100rpm

[drawkvw]

Ok so here is the deal. I bought the bus non running, I replaced every gasket I could without splitting the case. New manifold boots as well. I rebuilt the carb, set the valves and set the timing. For the life of me I can't get it to idle below 1100 rpm. There is a little play in the throttle shaft. I will look at making a paper gasket for that issue with a little wheel bearing grease to create a seal to see if that helps. I'm assuming it had to be a vacuum leak since screwing in the bypass screw all the way in let's it idle at 1100 rpm. It will raise the idle if I screw it out. I did the preliminary set up with 2 1/2 tuns on the volume control and 2 turns on the bypass screw. All gaskets are new for the intake and no ports on the carb are left unsealed. It is a bocar 34 pict 3 if that matters. I'm looking to hear anything and everything and I will try whatever is suggested to fix this issue. Thanks to everyone in advance.

[busdaddy]

Are you sure the throttle plate is closing completely? The stop screw that sits against the high idle cam must be barely touching the cam, only enough to take the slack out of the system and support the butterfly so it doesn't dig into the carb throat.
_________________
Rust NEVER sleeps and stock never goes out of style.

Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!

Слава Україні!

[williamM]

Do you have a timing light?-- you need to start separating all the events that mean a high idle- runaway timing is the first.

Your looking for anything that is advancing the timing- First place is the fast idle cam from the choke- the choke must be open and the fast idle steps off the adjuster screw from the throttle plate.-- If not the vac port to the timing advance will open and advance the timing. -- At the same time you can observe the timing for a dist malfunction. (set to 28* at 3500 RPM)

Test for a vacuum leak by dribbling some fuel into the carb at fast idle- if it instantly (and scarcely) jumps in RPM you have a vacuum leak. Shut it down and either acquire a smoker (by far the best way)- or apply a slight pressure to the intake and spray for bubbles.

you can also use propane (not light- ) to apply a fuel to areas of the manifold.

Get back to use after those tests and report.
_________________
some days I get up and just sit and think. Some days I just sit.

opinion untempered by fact is ignorance.

Don't step in any!

[drawkvw]

Yup it's nowhere close

[drawkvw]

Timing is set with the light

[williamM]

[drawkvw]

Yes that mark has been hit. Everything has been put to spec. Timing, valves, points, both screws on the carb, fast idle screw.

[drawkvw]

I saw this post on another forum and it could be relevant. What says the gurus on the samba


http://www.itinerant-air-cooled.com/viewtopic.php?t=9442

[busdaddy]

Then remove the carb and hold it up to the light to confirm there's nothing visible around the throttle plate, also look at the hole in the throttle plate, it may be for a DVDA and need a pop rivet or solder in it to plug it up.

Caution, when eyeing up carbs wear safety glasses, that first shot from the acel pump is always a nasty suprise
_________________
Rust NEVER sleeps and stock never goes out of style.

Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!

Слава Україні!

[drawkvw]

Ok I will pull it and give it a check, I hope your not speaking from experience with the fuel in the eye. That would suck, I'm a commercial plumber I got primer in my eye once.... most pain I have ever felt in my eye ever.

[busdaddy]

I've managed to stay very lucky, but have had a number of near misses that would have been plenty unpleasant if they were just a few mm closer. Never trust a carb, even if it's drained, pump the throttle after draining to empty the acel pumps too just in case.
_________________
Rust NEVER sleeps and stock never goes out of style.

Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!

Слава Україні!

[rockerarm]

Hi. Since a '71 has power brakes try and cap off the fitting on the intake manifold, below carb, and see if anything changes.
Do you have a distrib that its centrifugal weights are returning to base timing. You can verify by attempting to turn rotor. It will move only a small amount but once released should snap back to base timing.
If you have all the original components then there was a throttle positioner that would slow the throttle's return once driver lifted off the pedal. Check this component isn't allowing throttle to return.
Finally, seen the cable get hung up within the tube, especially the flexible tube near the trans.
Bill

[Abscate]

Throttle shaft leaks to win place and show. Those aftermarkets suck.
No, I mean they suck through the bushings.
_________________
.ssS!

[aeromech]

As Rockerarm said, block off the vacuum line going forward to the brake booster. Did you replace that vacuum hose? You could also have a failed booster.
_________________
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

[wcfvw69]

[Manfred58sc]

Be happy it idles at all...
_________________
Fat chick owner/operator

[kreemoweet]

I had the same deal going on once: my stock '71 bus engine wouldn't idle below 1100 rpm with any reasonable setting of the carb controls. That meant
it wouldn't pass state emissions test. Couldn't find any vac leak, fer love or money. Plugged hole in throttle plate to "compensate" for all that unwanted
air coming in from someplace. That improved matters a great deal.
_________________
'67 bug: seized by the authorities
'68 bug: seized by the authorities
'71 kombi: not yet seized by the authorities

Stop dead photo links! Post your photos to The Samba Gallery!

[drawkvw]

For the win!!!!! The man who called it first BUSDADDY!!!!!!!

[Spike0180]

Did you plug it up and confirm that it fixed the issue?
_________________
Brutis Patches Izabich: 1970 VW Transporter - 1776cc DP
Current State: Projects never truly end...
Location: Grosse Pointe, Michigan
Other cars: 2003 F150, 2003 Jetta GLI vr6-6sp

Sambastic: adj; the quality of being nit picky, elitist, expecting everyone to do things the way they believe is best with no regard to situation, "sambastic"

[drawkvw]

It's riveted and fixed my issues. Worked great