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Niels911SC
Samba Member
Joined: March 03, 2013
Posts: 38
Location: Sweden
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 Posted: Wed Jun 30, 2021 2:34 am Post subject: Rebuilt 1700 type 4 dual carb PDSIT won't idle with retard |
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I'm in the progress of getting my recently rebuilt 1700 type 4 engine (72 CB block) up and running. After struggling a lot with rebuilt carburetors that had leaky floats and clogged idle jets (so much for the rebuild..) I put the old Solex PDSITs back on (original 32-34 models, but from a 74 instead of a 72).
Thanks to a fellow Samba member I even got a NOS coil clamp with throttle return spring!
Now the car will start and idle on the chokes, but when it comes off the chokes after ~5 minutes and the retard kicks in (and it does, quite hard) the engine runs very low and stalls easily.
I also measured the idle airflow and I had to increase the throttle stop position on the left carb quite a lot to get them even.
Also when I partially block the CIS intake tube the idle goes up, but when I fully block it the idle goes down. It also goes down when I disconnect the CIS solenoid.
Any ideas about what's going on? My distributor is rebuilt and it worked fine on the old engine (although it seemed to pull quite a lot of retard, 10deg ATDC where it should be 5 for a '72, when timed to 28BTDC with all hoses off). |
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busdaddy
Samba Member
Joined: February 12, 2004
Posts: 51153
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Wed Jun 30, 2021 7:39 am Post subject: Re: Rebuilt 1700 type 4 dual carb PDSIT won't idle with retard |
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| Niels911SC wrote: |
| .....Also when I partially block the CIS intake tube the idle goes up, but when I fully block it the idle goes down......... |
That's a clue that the CIS mixture is too lean, turn the small vertical adjustment screw next to the intake CCW to richen it.
Have you seen this?: https://www.thesamba.com/vw/forum/viewtopic.php?t=399195&highlight=final+dual+adjustment
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Niels911SC
Samba Member
Joined: March 03, 2013
Posts: 38
Location: Sweden
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| Posted: Wed Jun 30, 2021 10:38 pm Post subject: Re: Rebuilt 1700 type 4 dual carb PDSIT won't idle with retard |
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I'll try richening the CIS in that case, thanks!
I have read that procedure and that's the one that I'm following, actually! But I don't get further then the timing step because when setting 28*BTDC with all hoses off, it retards so much when I put the hoses back on that the idle just stumbles and then it dies 
I read somewhere that the vac-can retard stop can be modified, but I didn't read how. If I can get it to stop retarding at 5*ATDC instead of 10+, maybe the bus will keep idling? I can't find out how though. |
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Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50352
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| Posted: Thu Jul 01, 2021 12:38 am Post subject: Re: Rebuilt 1700 type 4 dual carb PDSIT won't idle with retard |
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| Niels911SC wrote: |
I'll try richening the CIS in that case, thanks!
I have read that procedure and that's the one that I'm following, actually! But I don't get further then the timing step because when setting 28*BTDC with all hoses off, it retards so much when I put the hoses back on that the idle just stumbles and then it dies
I read somewhere that the vac-can retard stop can be modified, but I didn't read how. If I can get it to stop retarding at 5*ATDC instead of 10+, maybe the bus will keep idling? I can't find out how though. |
Some cans were designed to give 10° of retard and would require carbs that were design to be used with that much retard.
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Bus & Pickup 1973 * 1700 Manual Trans
Distributor: VW 021-905-205J, Bosch 0231 173 009 or 010 > 021-905-205N, 0231 181 005
Can Use: VW 021-905-205N, Bosch 0231 181 005
Points: 01 011
Condensor: 02 054
Rotor: 04 033
Note: Originally equipped with Speed Limiting Rotor 04 016 (5400rpm)
Dust Cover: 039-905-241, Bosch 1230 500 139 > 1230 500 147
Cap: 03 010
Distributor Cap Clip: 03-905-265, Bosch 1231 251 033
Parts Kit (Shims, Washers & Hardware): 059-998-211, Bosch 1237 010 007
Coil: 00 015 (Blue Coil: 00 012)
Vacuum Can: 07 113
Ignition Wires: 09 171
Spark Plug: W8CC
Timing Set At:: 10deg ATDC @ 800-950rpm w/strobe, vacuum hose(s) connected
Advance/Retard Range: Vacuum: 7-12deg Adv, 16-18deg Ret; Centrifugal: 9-14deg @ 2000rpm, 21-25deg @ 3400 rpm |
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Niels911SC
Samba Member
Joined: March 03, 2013
Posts: 38
Location: Sweden
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| Posted: Mon Jul 05, 2021 1:13 pm Post subject: Re: Rebuilt 1700 type 4 dual carb PDSIT won't idle with retard |
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Alright, so I checked, I have the vacuum advance/retard can with "885" on the arm, which should be the last three numbers of the Bosch nr, which in that case would be 1237121885 which conforms with the VW nr 021905271B.
So by that account I should have the right vacuum canister.
Today I timed it again with both hoses off to it's maximum advance, 28 degrees BTDC and you can really see it become stable at high RPMs, so I'm sure that's maxed out. Then hooking both hoses back up the idle drops all the way to ~650RPM. The timing is then around 16ATDC, when I manually bring up the RPMs to ~900 by pushing on the crossbar I still get ˜12ATDC, which is way more then the 5ATDC it should be.
In some thread I read that it should be possible to limit the amount of retard, but no-one seems to have described how! |
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Niels911SC
Samba Member
Joined: March 03, 2013
Posts: 38
Location: Sweden
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| Posted: Mon Jul 19, 2021 11:24 pm Post subject: Re: Rebuilt 1700 type 4 dual carb PDSIT won't idle with retard |
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| Just to report back, I found out how to modify the maximum retard (and also found my problem). When you remove the vacuum canister there's a little stop post that that arm is stopped by when the vacuum is applied to the retard side. That little stop can be bent so that the maximum retard is decreased/increased. On my vacuum canister it looked like someone had bent it before to increase the retard, so I bent it back to it's original position (just straight at a 90degree angle) and now it retards to about 5ATDC as it should. |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Tue Jul 20, 2021 8:57 am Post subject: Re: Rebuilt 1700 type 4 dual carb PDSIT won't idle with retard |
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| Niels911SC wrote: |
| Just to report back, I found out how to modify the maximum retard (and also found my problem). When you remove the vacuum canister there's a little stop post that that arm is stopped by when the vacuum is applied to the retard side. That little stop can be bent so that the maximum retard is decreased/increased. On my vacuum canister it looked like someone had bent it before to increase the retard, so I bent it back to it's original position (just straight at a 90degree angle) and now it retards to about 5ATDC as it should. |
Finally!  ....someone else finds and gets what I have been saying for many years!
The little stop post you are speaking of can be bent, can simply ve increased in diameter with a thin metal or plastic ring or sleeve.....or quite a long time ago on one can....I have drilled out the rivet to remove the post, drilled and tapped a hole in it and locktighted in a stud. It gave it about a +/- 3° of adjustment. Lock nut in outside.
Another can I took a section of about a 3/8" diameter steel rod.....drilled a hole through it offset from the center.....put in a 2mm set screw as a,stud and locknut on the outside and made an "eccentric" adjuster that could be accessed and adjusted while the engine was running.
If you need to.....you can also add permanently to either retard or advance by piling away at the notches on the arm.
You can also add an adjusting stop screw for advance....just like the model that came in 411/412 and 914 cars.
There are a bunch of ways you can make a vacuum can that is not made exactly for your engine....work with your engine. Ray |
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SGKent 
Samba Member
Joined: October 30, 2007
Posts: 41031
Location: Citrus Heights CA (Near Sacramento)
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| Posted: Tue Jul 20, 2021 11:27 am Post subject: Re: Rebuilt 1700 type 4 dual carb PDSIT won't idle with retard |
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some of the dual vacuum cans were one size fits all. There was a small allen head screw that had to be adjusted. One got to it thru the vacuum nipple. I am 100% sure of this because the last couple dual cans that I bought from the VW dealer (Econo Motors - Riverside CA) came with the instructions and allen wrench to adjust it. The part superseded the original VW labeled cans, which went NLA from VW about 1977.
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Tue Jul 20, 2021 12:33 pm Post subject: Re: Rebuilt 1700 type 4 dual carb PDSIT won't idle with retard |
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| SGKent wrote: |
| some of the dual vacuum cans were one size fits all. There was a small allen head screw that had to be adjusted. One got to it thru the vacuum nipple. I am 100% sure of this because the last couple dual cans that I bought from the VW dealer (Econo Motors - Riverside CA) came with the instructions and allen wrench to adjust it. The part superseded the original VW labeled cans, which went NLA from VW about 1977. |
Thats really cool. I have never seen any like that but it makes sense.
This is the only factory adjustable one I have seen (other than some of the 36 or 40 horse cans). This one was from a 411 or 914 1.7L
Ray |
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SGKent
Samba Member
Joined: October 30, 2007
Posts: 41031
Location: Citrus Heights CA (Near Sacramento)
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| Posted: Tue Jul 20, 2021 1:52 pm Post subject: Re: Rebuilt 1700 type 4 dual carb PDSIT won't idle with retard |
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when you opened the box VW supplied instructions with many models on it for bus and beetle. Each one had a different number of turns (whole and fractional). I think both nipples were straight instead of the advance side angled up but it has been a long time. Someone with a fiche from the late 1970's might find the superseded part number.
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