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Engine idle and ignition timing issues

Discussion in 'Engine & Transmission' started by Doob, Aug 4, 2021.

  1. Doob

    Doob Member

    Messages:
    49
    Location:
    Perth
    I am having all sorts of difficulty getting my 1971 low light Kombi to idle. I am hoping someone can offer some words of wisdom.
    Background Info & Specs –
    The vehicle Compliance Plate is dated 10/71. The Engine is a stock standard 1600 cc dual port (AD code). The valve clearance is set at 0.006” (engine cold).
    The Carburettor is a single Solex 34-PICT-3 (German) – Main Jet X127, Pilot jet g 55, Air Correction Jet 120z. All jets and fuel passages thoroughly cleaned. Electric cut-off & automatic choke seem to be working. Initial setting of the carburettor idle speed & the mixture screws are both 2-1/2 turns out from fully in. The throttle fast idle screw is in ½ a turn.
    The Distributor is a Bosch 0231 167 049 / VW 113 905 205 AJ (centrifugal & single vacuum advance), and the Condenser is a Bosch – VW 1 237 330 204. I am guessing these are original, but not sure. The points are new(ish). The gap is set at 0.016” and the dwell angle 47 deg – no pitting or discolouration evident.

    The Ignition Coil is a Bosch 12A 905 009B. Primary winding ~ 4 ohms - Secondary ~ 8k ohms. Possibly original, not sure.

    The Spark Plugs are Bosch W8AC with gap set at 0.024” – The plugs are new(ish) with small amount of soft black deposits that is easily cleaned off. The high tension spark plug leads are new.

    The crankshaft pulley has 2 markings on it. A dimple marking on the outer rim that I assume is TDC for #1 piston, and a single notch on the inner rim some ~ 7mm to the left of the dimple. This notch would be approximately 5 deg ATDC. (see attached photo).

    The static ignition timing was initially set at TDC (points opening at TDC dimple align with crankcase join). However I could not get the engine to idle at this timing. I needed to set the static timing a few degrees BTDC to get the motor to idle.

    I am finding seemingly conflicting published data on the recommended timing - from 5 deg ATDC to TDC to 7.5 deg BTDC. The Bentley Manual does not identify this engine combination. I suspect the specified idle timing should of 5 deg ATDS, and I guess this corresponds to the notch on the inner pulley rim. But I am unable to get the engine to idle at this setting.

    Questions

    Is my 1600cc duel port, AD code engine, with the Solex 34-PICT-3 carburettor, and 113 905 205 AJ distributor, a standard & acceptable combination for a 1971 manual T2 Bay Kombi ?

    What is the recommended target ignition timing for this combination?

    Is the crankcase pulley correctly marked for this combination?

    Any suggestions on trouble shooting the poor idling situation would be much appreciated.
     

    Attached Files:

    Last edited by a moderator: Aug 4, 2021
  2. oldman

    oldman Super Moderator Staff Member

    Messages:
    10,613
    Location:
    Avalon Beach NSW
    Hi Doob….My son’s ‘71 has a 1600 stock config.
    From memory, I’ve always set the timing to 7.5 deg. BTDC.
    Timing mark ( notch on pulley) set to line up with the join in the crankcase
    Worth checking your earth connection at the battery too.
    I’ll go back through my notes and check……
    Hope it’s something simple
    Cheers,
    Mark
     
    Last edited: Aug 4, 2021
  3. Barry

    Barry Well-Known Member

    Messages:
    5,893
    Location:
    Abbotsford NSW
    Hey Doob

    think your info is about US motors - I can’t download stuff

    I find best info on tuning here

    http://www.vw-resource.com/

    Timing is ~ 7.5 degrees BTDC (the nick) on the front of the pulley (back is back!! :) ) and the dimple on the rear it TDC

    1DCA666E-53DA-401D-8851-C3C3708A155F.jpeg

    That said - once set you should adjust to about 35 degrees max advance at 2,500 revs
     
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  4. oldman

    oldman Super Moderator Staff Member

    Messages:
    10,613
    Location:
    Avalon Beach NSW
    Thanks Barry…..got my marks mixed up !
    (Now edited….)
    I think I wiped a bit of white paint into the 7.5 mark to avoid confusion at the time……
    Cheers,
    Mark
     
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  5. cbus

    cbus Well-Known Member

    Messages:
    13,475
    Location:
    sunshine coast
    Check that idle air screw O ring is in good Nick.
     
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  6. galp

    galp Member

    Messages:
    90
    Location:
    ulverstone
    Spray some aerostart or similar around the sealing area at base of the carb and the rubber boots on the inlet manifold to see if the idle picks up due to air leaks
     
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  7. 1500king

    1500king Well-Known Member

    Messages:
    1,617
    Location:
    Adelaide, SA
    I can help.

    It is the correct combination for your 71 AD code bus, from AD 000 002- AD 290 640.

    Yes, you have the correct pulley. Below are timing specs.

    Firstly, I need a bit more info on the carb. On the bottom left side of the flange where the carb mounts to the manifold, if it is an original VW carb, it should have some small stampings. What are they? Looking at the 120Z emulsion tube, I reckon it might be the original VW299-2 carb. Can you confirm this? Also, take the top off the carb. You should see 2x power fuel jets next to the choke plate, sticking out like little sticks. Under the cover, can you confirm the tiny number stamped into the casting? It should be 95 which is the size of the power fuel jets and these are bigger than the equivalent beetle carb for obvious reasons(pushing a brick).

    If it is a 299-2, then it will also have a 4mm vacuum off-take just above the venturi drilling plug(facing you when you look at it in the engine bay)..probably blocked off....

    You need to go BIGGER on the main jet to X140.

    You need to go bigger on the idle(pilot) jet to g60.

    Idle stop screw 1/4 turn in from touching the fast idle cam in hot running position.

    Distributor 113905205AJ is correct for that carb...BUT... if you say it has a single vacuum, then that part is wrong. It is a DVDA distributor, not SVDA distributor. It needs the Dual Vac can (bosch with 851 stamped on the operating arm of the vacuum can. What is yours?). This is why you have the 5 degree ATDC pulley. The retard side of the vac can goes to that 4mm blocked off pipe i mentioned above, while the advance side to the left side of the carb vac offtake.


    You then time them to 5 degrees after TDC( That mark to the left of the outer TDC dimple ) ..WITH ALL HOSES CONNECTED TO THE DISTRIBUTOR and keep motor rpm between 800-900rpm (hot running position, throttle stop at bottom of fast idle cam-throttle closed).

    Dwell is 44-50 degrees. gap is 0.015", not 0.016".

    You CAN use the single vac can in the dizzy if it is a 461 can(marked on the arm). Timing then goes to 7.5degrees BEFORE TDC at 800-900rpm, but with the vac hose to the vac can disconnected when you are timing it. You will need to create a 7.5 degree BTDC mark on the pulley for that- to the right of the TDC dimple. It wouldn't have run well if you timed it to 5 ATDC without dual vac input.

    POOR IDLING INFO:

    As a test- disconnect your power brake hose from the inlet manifold and block it at the manifold. See if you can tune it more easily and it holds a steady idle..... You might have a vacuum leak in the brake booster/vacuum lines(common). Go and find/fix it.

    Are your warm air controls connected? You need the warm air flap and thermostat working to keep constantly warm(at 35-40c) air coming into the carb. Helps with keeping fuel atomised on cooler days = smooth running.

    Is the preheat tube clear on the inlet manifold? Unblock it and use the manifold preheating from your exhaust. This prevents fuel condensing in the manifold before it reaches the heads =smooth running.

    Is the engine air flap control and thermostat setup connected and working? If not, your motor will never warm up/ temps and tune will be all over the place, wear out faster, maybe die from catastrophic failure(head issues) and use more fuel. Only time you don't need them is if you are driving in 35C+ 100% of the time. VW was a cut price manufacturer..and they still installed them..why?.

    Coil is correct, VW Australia 12v item (12A). Primary winding seems a bit high, should be more around 3 ohms. Secondary is ok.

    Plugs are ok. Use wire leads, 0 ohm leads with the bakelite 1 k ohm resistor in them. It's a fairly low voltage ignition, you dont want to be adding anymore unnecessary resistance.

    The Bentley manual was published under permission by VW of AMERICA. Therefore all their standard specs are our M157 optioned smog specs . Some here had it, others did not. We also got the euro specs.

    Let me know how you go.

    If you need the 7.5 timing mark measurement for the single vac can, or if you want to keep it original, I also have NOS 851 vacuum cans with the correct green braid 4mm retard hose. I also have all the carb jets if needed.
     
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  8. 1500king

    1500king Well-Known Member

    Messages:
    1,617
    Location:
    Adelaide, SA

    This will hurt the motor with detonation imho. Under load, that is 20 more degrees than it will safely take at 2500rpm. These distributors (including the 113905205AL and 043905205B top out at 3800 rpm, so there's still another 10 degrees of mechanical advance in it above 2500 rpm.
     
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  9. Doob

    Doob Member

    Messages:
    49
    Location:
    Perth
    Thanks everyone for your comments - this is such a great forum!
    I am providing a little more information & clarification below. Also see attached, 3 pdf files with a few photos.

    The Distributor (Bosch / VW 113 905 205 AJ - with a 851 vacuum canister)

    My previous terminology for the vacuum advance may have been a little naive. So to clarify.... The vacuum canister control arm is stamped '851'. However there is only a single 3mm hose running from the left of the carby to the canister. There is a second take-off pipe on the canister but there is no hose connected. There is a 4mm pipe on the rear side of the original carby, but this is capped off.
    With the distributor cap off and taking a 'healthy' suck on the 3mm hose I can see the vacuum canister advance arm function - with no air leaks evident. If I disconnect the hose with the engine running (and block the carby 3mm pipe) the engine revs drop. So I assume the vacuum advance is working, at least to some degree. However if I take a suck on the 4mm canister pipe, I just draw air - there is little or no resistance. Is this normal ??
    With the 3mm vacuum hose attached, I can get the engine to idle (just) at a static timing of TDC - but it is rough and it stalls frequently. The idle improves considerably if timing is advanced a few degrees BTDC.

    So....some distributor questions?
    What is the correct terminology for my distributor? I guess it is a DVDA, but has been acting as a SVDA given the lack of the second vacuum hose?
    Should I be adding a second 4mm retard hose to the 851 vacuum canister? [I am not sure of the integrity of the retard side of the canister ??].
    Is there an easy 'bench test' way to check the 851 vacuum canister diaphragm(s) and to check that the advance & retard action is acceptable?
    What are the target ignition timing specs for this Bosch/VW 113 905 205 AJ - with a 851 vacuum canister distributor system (with one or both hoses)? e.g.The static timing - idle timing with or without hose(s) attached? And what higher rpm (no load) advance I should be looking for?

    The Carburettor(s) VW Solex 34-PICT-3
    I have two VW Solex 34-PICT-3 carburettors (both German).
    The one that was originally on the motor is stamped VW 299-2/B1 127. It is jetted with Main Jet X140, Pilot Jet g 60, and air correction jet 120z. The number stamped on the cap housing (dual power jet size) is 95. It has a 4mm vacuum take off pipe on the rear. This pipe is capped off (no hose attached). The idle mixture screw & seal look OK ...to my untrained eye. There is a small amount of wear on the throttle shaft bushings - but not excessive I think.
    With the difficulty I was having in tuning the engine at idle, it was suggested it might be an issue with this carburettor, so I changed it out.

    This second carburettor is stamped VW 355-3/B3 281. It is jetted with main jet 127.5, Pilot jet g55, and air correction jet 120z (i.e. more in keeping with the USA Bentley Manual jet specs).
    The number stamped on the cap housing (dual power jet size) is 95.
    This carburettor does not have the rear 4mm vacuum pipe installed - the port has been plugged with a metal bung.
    The idle mixture screw & seal look OK - but it is much easier to turn than on the originally carby (perhaps TOO easy to turn?!).
    The throttle shaft bushings had been refurbished by the previous owner of this carby, and I am confident they do not leak air. They are perhaps a little too tight now, as the throttle does not shut off so readily when taking the foot off the pedal!

    So...some Carburettor questions.
    I guess my original VW 229-2 carby may have initially had a 4 mm retard vacuum hose attached to the 851 vacuum canister? Why would this hose have been removed and the 4 mm carby take off pipe be capped off??
    I guess my second VW 355-3 carby (with no 4mm vacuum pipe outlet) may not be ideally suited to the 851 vacuum canister? Or at least not timed to 5 deg ATDC. If running with a single 3mm advance hose, is this combination acceptable at some BTDC timing? Or, to use this carby, should an alternate vacuum canister be used (e.g a 461 canister or another)?
    I guess if using this carby, it should be re-jetted as per my original carby [rather than the USA Bentley jet specs] ?

    Crankshaft Pulley
    The only markings on my pulley are for TDC and 5 deg ATBC. In keeping with the DVDA dizzy I guess. With a bit of basic geometry and a paint pen, I can add additional temporary markings on the pulley for target BTDC timings.
    What additional marking should I consider? [i.e. for static & idle timing, and for checking higher rpm advance]?

    Inlet Manifold (Part No 113 129 701 AF)
    I have checked the obvious places for air leaks - e.g checked gaskets, seals, bolts and clamps - sprayed a little WD-40 on connections with engine running - plugged the brake servo take-off port ..etc...I have not discovered any inlet air leaks (yet!).

    Heat Tubes
    For the inlet manifold pre-heat tubes ....mmmm. The tubes are rusted out above the exhaust manifold. The exhaust manifold flanges had been plugged off. I recently acquired a used replacement inlet manifold [ No 113 129 701 B verses my current 113 129 701 AF] - but it does not have the 0.5" vacuum take off pipe for the brake servo. Apart from adding the 0.5" pipe, the work involved in changing out the inlet manifold has caused me to procrastinate about this job. But I guess if I am sticking with a stock standard single Solex carby set up, I should get onto it!!

    Engine air flaps & controls
    All the engine tinware, air flaps, controls and thermostat are in place & connected. However the bellows type thermostat does not work (leaking air I guess). I have been unable to find a reliable NOS/OEM thermostat (No 111 119 159a) as yet.
    There are a couple of suppliers in USA advertising aftermarket thermostats .. e.g Awesome Powdercoat and Aircooled.net
    https://www.awesomepowdercoat.com/vw-thermostats
    https://vwparts.aircooled.net/Thermostat-Type-1-65-70C-111-119-159A-p/111-119-159a.htm
    I have also seen internet postings on repairing these old thermostats, but not sure how reliable this repair method might be. e.g. See previous kc forum post
    https://forums.kombiclub.com/threads/thermostat-repair.59263/#post-677675

    I would value any comments on this.

    Note: My 1971 Kombi does not have any thermostat controlled warm air supply to the carby/air cleaner intake. It has a stock standard oil bath air cleaner mounted to the right of the motor.
    See photos in the attached pdf file for the second carby - second page.

    Electrical
    I did previously check the battery terminal, earth strap connections, ignition system wiring ..etc.. and could not see any obvious problems.
    However... while I could get a reasonably stable Dwell Angle reading (47 deg) using my digital multi meter, I could not get a reliable stable tacho reading. The meter reading was erratic, bouncing around at much lower rpm readings than my estimate of engine speed. [e.g.. at a fast idle the multi meter tacho was indicating 400 - 600 rpm].
    I also have a new(ish) analogue VDO tacho gauge. This also gives erratic rpm readings.
    [And yes ...I have connected the multi meter and VDO gauge as per instruction book - and both are set for 4 cylinder ;)].

    Apart from a malfunction of both my multi meter and VDO tacho - what could cause these erratic end erroneous rpm readings? Are there potential issues with the ignition system that could cause an erratic corrupted pulse signal??

    Shopping List !
    What items should I be putting on my shopping list? What should be the priority items?
    Andrew(1500king) - rather than make this post even more long winded, I will contact you separately to see what items you can supply.

    Thanks again to everyone for their comments & advice given here - it is very much appreciated.
     

    Attached Files:

    Last edited: Aug 10, 2021
  10. 1500king

    1500king Well-Known Member

    Messages:
    1,617
    Location:
    Adelaide, SA
    The carb is out of adjustment. There should be no change in rpm. This is the 'ported' vacuum advance side and orifice should be covered by the throttle plate at idle. The stop screw at the end of the throttle arm where it contacts the fast idle cam needs to be set so that in the cam hot running position(choke open, fast idle cam pointing up) the screw is 1/4 turn from the throttle valve being fully closed(1/4 turn in from no contact between the fast idle cam and the stop screw). The advance diaphragm, however, is working.

    No, it's not normal. Sounds like you have the correct vac can, but the retard diaphragm is faulty. Does it have 851 stamped in the control arm?

    It's a DVDA. The advance start and finish points occur under considerably more vacuum than the SVDA vac can, so there will be dead spots in acceleration/ running due to insufficient shift of timing between power and cruise.

    No, the vacuum can is faulty.

    Not really, Apart from checking that the arm is not seized and the diaphragms are not leaking, the rest needs to be done on a distributor test machine and compared to the factory distributor graphs (in 1968-74 factory workshop manuals).

    800-900 rpm, both vac pipes connected, 5 ATDC(your timing mark to the left of the TDC dimple). You need both hoses.

    With no hoses connected, mechanical advance is the following, from it's start point:

    1000-1250rpm ----start advance
    1500rpm ---- 9 degrees advance
    3800rpm ---- 23.5 degrees advance

    Vacuum advance:

    start ---- 135mmHg
    finish ---- 235mmHg ---- 10.5 degrees.

    Vacuum Retard:

    start ---- 105mmHg
    finish ---- 195mmHg ---- 12 degrees


    This IS the carb to use. Check other areas for vacuum leaks. Can be rebuilt, no issues

    This one is a bit of a mish-mash of jets and top housing. With an overly tight throttle shaft, I'd park it. BTW, it's a 1600 bug carb.

    Well, the bad retard diaphragm would have been a big vacuum leak (for vacuum retard, it's manifold vacuum, so uncontrolled vac leak), hence why it may have been blocked off. The other, and don't want to offend anybody, but 99.9% of folks can't time a garden variety SVDA, let alone something different like this. I had one last week(standard 7.5 degrees btdc SVDA, vac hose off) that was timed previously 25 degrees too advanced. What were they thinking?

    It's a bug carb for the 113905205AL dizzy (461 SVDA vac can). Yes, you can use a 461 can, then time it to 113905205AL spec(7.5BTDC @800-900rpm, vac hose OFF). You will also need to mark 7.5btdc on the pulley. It needs a richer air corrector(60Z) and 130 main just to run in the bug. 95 power fuel jetted lid is from a bus carb (originally dual 85 for beetle), also why it doesn't have the vac retard offtake.

    Don't use the Bentley specs. They will also be jetted for EGR too.

    If you want to run the 461 vac can to AL spec, the carb needs to become a VW359-1. x125 main,60z emulsion tube, g60 idle.


    The distance to the the 7.5btdc mark from the 5ATDC mark on your pulley is 19.5mm. Measure to the right of the 5ATDC mark. You can statically time it to 7.5BTDC, and once running (both vac lines connected assuming you are keeping the AJ dizzy and everything is fixed), finish it off with a timing light (but it will be close). You can work out other distances with the above measurement I gave you with advance specs for the dizzy.

    Good. The brake servo port is a common one. Best to get the motor running properly without it for now (do not drive without your power brakes)..
     
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  11. 1500king

    1500king Well-Known Member

    Messages:
    1,617
    Location:
    Adelaide, SA
    Before you start, double check the B manifold ends are the same diameter as the one you have. It might be an early 1300 twin port manifold. Plenty of folks caught out by that one. Otherwise, if you are handy with the welder, you can install the 12mm offtake for booster. Will need to clear out the the preheat tube too. It will probably be blocked.

    Yes, Pull the motor out of the car! :)


    Yes, I buy in and use these. They work well. 65-70c. It's worth pulling the fan housing to degrease the inside and cooling fan if you are using cabin heaters. Also a good opportunity to degrease the heat exchangers internally.... only if it hasn't been done already. Can give the generator a birthday with new high temp sealed bearings too.

    Don't bother. Most of them crack in the bellow It will just fail again in short order, IF you find the hole and repair it.

    It won't have one either being a 71. This started on later models.

    Yes. Bad condenser and/or wire, incorrect contact breaker gap/ dodgey GB534 bosch points, bad coil, broken ground pig-tail wire on the breaker plate in the dizzy.

     
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  12. Doob

    Doob Member

    Messages:
    49
    Location:
    Perth
    Many thanks 1500king - most impressed !!!
    Will be in contact about a shopping list!
     
  13. cbus

    cbus Well-Known Member

    Messages:
    13,475
    Location:
    sunshine coast
    Deep breath before continuing :D
     
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  14. Barry

    Barry Well-Known Member

    Messages:
    5,893
    Location:
    Abbotsford NSW
    I’m going to have to take a week off work to read this post
     
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  15. syncro

    syncro Well-Known Member

    Messages:
    10,243
    Location:
    Southern Highlands
    I'd be doing the factory single advance/jet modification on it first. Much better driveability and fuel economy.
     
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  16. Doob

    Doob Member

    Messages:
    49
    Location:
    Perth
    Thanks Syncro,
    What did you have in mind?
    Are you suggesting the "461 vac can to AL spec, the carb needs to become a VW359-1. x125 main,60z emulsion tube, g60 idle." as one of the options given by '1500king above' - or some other single advance/jet modification?
     
  17. syncro

    syncro Well-Known Member

    Messages:
    10,243
    Location:
    Southern Highlands
    What 1500 king says. He is not a 025 115 611B.
     
    Last edited: Aug 11, 2021
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  18. 1500king

    1500king Well-Known Member

    Messages:
    1,617
    Location:
    Adelaide, SA
    It's just tighter timing control off idle and the idle timing is just for afterburning of HC's. There's no disadvantage. The SVDA is just what most are used to. Can do either. Either way, you are going to need a vac can, whether it's a 461 or 851 and jet depending on which way you go. Nice one re 025115611B!! Lol!!
     
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  19. syncro

    syncro Well-Known Member

    Messages:
    10,243
    Location:
    Southern Highlands
    The DVDA engine was the Australian version of dieselgate. Make an engine that complies with the new ADR2x emissions that uses lots of fuel and has flat spots, then make a kit to fix it free under warranty when the owners complain.
     
  20. 1500king

    1500king Well-Known Member

    Messages:
    1,617
    Location:
    Adelaide, SA
    There was a supplement in the fuel system VW factory data relating to flat spots. It was the carb, not the dizzy. I take that into consideration.
     
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