Static Timing for 73 Thing

[Ozmello]

A little background, the Thing is at our Florida home while we summer in Kentucky. Back in August we were at the Florida home doing maintenance and the Thing left me by the roadside after a wire popped off the fuel shutoff solenoid, and then the starter wouldn't crank. While troubleshooting, I took the distributor cap off which is when I discovered that the distributor hold down clamp bolt was stripped. I installed a new starter, put some extra washers on the hold down clamp bolt so that it could be snugged sufficiently to keep the distributor from moving and statically timed the car to 7.5 degrees BTDC. Found the timing mark by rotating the crank pulley. My pulley has a dimple on back rim and a notch to the right of the dimple which I believe corresponds to 7.5 degrees BTDC. Dimple corresponds to TDC per distributor rotor position and distributor notch. Car now starts easily but won't maintain an idle. Prior to all this is idled well and I'm sure that the cylinder firing order is correct, 1-4-3-2. The distributor has a vacuum advance and I believe is the original item.

After looking at the shop manual on this site, I'm now wondering if I shouldn't have timed to 5 degrees ATDC, a point which is not marked on the crank pulley. I've talked the wife into making another trip down to the Florida house this coming week so that I can look into some maintenance items, but primarily so that I can see if I can get the Thing running well enough to get it to high ground in the event that storm season gets amped up (had a 10' surge with Helene last year).

Any advice and/or comments on if advancing the timing by 12.5 degrees as it appears I have would cause the car not to idle? The fuel shutoff solenoid clicks when given 12V. That, and the fact that the car starts and runs if I modulate the accelerator, tells me that the solenoid is not the issue.

[heimlich]

If it's not idling your idle jet could have debris in it. This usually happens when I leave my cars sitting too long.

If you have the single vacuum canister use the 7.5 timing. If you have the dual vacuum canister use the 5.
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[lqqkatjon]

I have been dealing with my 73 VW thing all summer. changing distributors and points a bit for various reasons.

what I have found out is I had bad problems trying to time it staticly and for idle. So what I found seems to work, and you will read it other places on this forum.... I "try" to static time it. at least I know where #1 spark plug is, and wire, and rotor pointing and I have that all marked. also marked the pully with a good white paint marker on the timing mark.

then I try to start it and it seems it doesn't want to start. so I move the distributor ever so slightly and it fires off. then I set my adjustable timing light to 28.5 degrees, and I crank it to 3000 RPM's and have that white timing mark on the case 1/2. and then drive it around the block. and it usually runs not so great... idles well, and drives, but it cuts out, ectt. but around the block it is warm now. So I again crank it to 3000 RPMS and set that at 28.5. then it seems to idle fine and run well.

I have fine tuned a little bit and put a little more advanced in it. but also had to adust the pict 31 to get the idle down again. but now I seem to be running 29 degrees at 3000 rpm and it is doing fine.


but I just have not yet this summer static timed it to 7 degrees and have it want to start. I usually have to turn it one way or the other a little bit to get it to fire up and idle well enough for me to go from the steering wheel/key to the engine to use the timing light. and set the all-in timing rather then the idle timing.

[Ozmello]

Finally got back to the car. As information, the car is actually a Safari, which is exactly like a Thing except where it ain't. I found out that it will start and idle, at a high speed, so long as the choke is closed. Once the choke opens the engine loads up and dies. I played with the static timing, both at 7.5 btdc and 5 atdc with no real difference. I've also played with the volume and bypass screws finding that I can keep the engine running by sawing the bypass screw in and out. I'm ready to pull and check the idle jet but am confused as to where it is.

The engine, rather than being an AM is an AF which JBUGS says was built for low quality fuel. The carburetor reads VW 34pict3 Bosch on the driver's side of the float chamber. The carburetor looks similar to the one shown in the shop manual but includes three interconnected hoses. I'm thinking that the hoses balance air between the idle jet, the pilot jet and some other orifice. Any thoughts? Guidance on where I would find the idle jet? Would a new 34pict3 that doesn't include the air hoses be a drop in?

[vws-microcars4jim]

Sounds like a vacuum leak to me. Have you tried spraying the throttle shaft area with carb cleaner or starting fluid ? (Be careful and have a fire extinguisher on hand). If it smooths out or changes when sprayed around there... you have a leak. I had similar idle issues until I did this test and found the bushings were worn. Sent my carb out to Tim at volksbiz for rebuilding and it never ran so well (and idles great) after that.

Interesting brace on the front, wonder why they added that? Looks unneccessary. Carb should have studs with nuts underneath, even if modified for the alternator. Are those both tight?

Jim

[SilverThing]

Warning: long post ahead. I can't help myself...

AF code engines is one of the engines offered for the 181 starting in the 1974 model year and was used until the end of production (simultaneously with other codes). It was introduced earlier on non-US bugs and buses in the 1971 model year as a low compression engine. Compression ratio is listed as 6.6:1 to run 83 research octane (RON) fuel. In the US our AKI is an average of research and motor octane - 91 RON in the rest of the world is considered equivalent to our 87 octane regular unleaded. Power output is 46 DIN BHP @ 4000 rpm, and 100 NM of torque @ 2600 rpm. I used the DIN ratings because they are consistent across years unlike the change from SAE Gross ratings to SAE Net ratings in 1972. Gross were measured without air filters, mufflers, cooling fans, etc while Net is closer to as installed in the car. A lot of people mistakenly associate a big drop in horsepower in the 1972 as being a result of smog requirements. To be fair, a lot of companies ended up reducing horsepower to meet smog, but it wasn't as extreme as it is/was made out to be. On VWs it was about 2hp mostly due to reducing the compression ratio slightly via a small dish in the pistons. Sorry for the double tangents.

As an aside, the AF engine code has been a head scratcher for me. The 1971 model year 181 got the AG code, which was also low compression. The difference is the AG engine uses a smaller carburetor (31 PICT-3 same as the european 1300DP engine) and only makes DIN BHP 44 @ 3800 rpm, 100 NM torque @ 2000 rpm. It strikes me as odd that VW would have created a separate engine for the 181 in 1971 rather than just using the AF from the get go. The other oddity to me is the AF and AG codes were used simultaneously in 1974 and 1975. *shrug* No one asked me at the meeting when that was decided (I wasn't there nor born yet ).

Your carburetor is a Mexican market smog version (Bocar is the manufacturer not Bosch). I'd venture a guess that it is a replacement sourced from a later mexican beetle. I don't think the 181 would have gotten it originally, but my knowledge on details of late Mexican safari is a little sparse. One neat feature is that carburetor has vacuum actuated main and idle jets, which I believe were to richen the mixture when the engine is cold and lean it once the engine is warmed up. I thought there was an electronic valve to control that operation, but I might be mistaken. I have one of those carbs in my stash, but I have never run it on an engine to know exactly what all it does or which way the vacuum works on the jets. I don't know if vacuum on the jets causes them to go lean or rich. I'd guess rich, but I could be wrong. Fingers crossed the vacuum actuated jets aren't some of the difficulty you are having.

Your distributor is what we call an SVDA (single vacuum dual advance). Static timing of 7.5 btdc should allow you to get it started. I would recommend setting the timing with a timing light at idle, once you can get it to idle (more on that below). Use a timing light to set it at 7.5 btdc with the vacuum hose disconnected from the can and plugged (to prevent air leak at the carburetor). If you haven't already done so, I would recommend making sure your ignition system is in good working order. This includes the plugs, wires, cap, rotor, points & condenser (or points replacement unit), and coil. I don't recommend just blindly replacing everything because that wastes money and doesn't help you learn to diagnose issues. We can go over what to look for on the ignition system, if you need. The addage with VWs is most fuel problems are actually ignition related. It has certainly been true in my life.

Lets make sure your carburetor is in good order and have you adjust the automatic choke as a starting point. The goal is for it to be on for the least amount of time (otherwise you are wasting fuel and potentially wearing our your cylinders faster because fuel is washing the oil off), but not opening so fast as to give you stalling issues while warming up. When I was younger (20 years ago) I tried setting the choke with the engine off, but ignition on using a stopwatch from cold to fully open. I forget how many minutes I was targeting. I want to say 3-5 minutes depending on the temperature, but I have slept since then and am probably misremembering. I didn't find the method worked that well anyways so I wouldn't recommend it. What I do now, is have the choke cold (like from sitting overnight), loosen the three screws so I can turn the electric choke housing and I loosen the choke all the way (no tension on the bimetal spring inside). With the air cleaner hose off, I then close the choke plate by hand and hold it. I then rotate the electric choke housing until I feel the bimetal spring just barely touch the choke plate arm. I then tighten the screws back down. Some people find that they need to re-adjust the choke seasonally. The last time I adjusted mine, I must have luckily gotten it just right as I haven't need to adjust it since. For the life of me, I can't remember what the outside temperatures were when I got it just right. On mine, the choke doesn't close quite all the way in the summer and stays closed a little longer in the winter. I don't have issues with it stalling warming up at idle or driving off immediately (driving off immediately is preferred unless you need to defrost/defog windows for safety).

You might try setting your carburetor adjustment screws (the ones on the driver side) to the common initial settings which is gently bottomed and then out 2-3 turns. Most people go with 2.5 turns for both. Some people will mistakenly mess with the screw on the throttle arm, which will cause all sorts of grief (it WAS adjusted for idle on EARLY VW carburetors, which causes confusion for folks on the later carburetors that most 181 have except for the 1970 model year and non-stock). The throttle arm screw should be set at a 1/4 turn from touching the bottom step of the choke cam (ie back the screw off so the throttle closes all the way, turn it until it barely touches, and go a 1/4 turn more). If that throttle arm screw is turned too far, it will unblock the distributor advance port (advancing your timing) along with uncovering off-idle progression ports (messing with your mixture). If the screw is backed off all the way, the throttle plate will wear the body of the carburetor. Once set, you shouldn't have to mess with the throttle arm screw again (and I would advise against it).

Once you get the engine to start and stay running (hopefully), try to get it to warm up before doing the final adjustments otherwise you may end up chasing your tail the next time you start it from cold. As a heads up, you might be in for a little bit of a dance getting everything set, but it shouldn't be too difficult. You will need to get the engine to idle at 850-900rpms by adjusting the big idle air bypass screw (I normally err on the side of 900 rpm). Once you got it at 900, you will need to set the ignition timing with a timing light (again with the vacuum hose disconnected from the distributor can and plugged to prevent an air leak in the carburetor). You will probably find that the idle rpms have shifted up or down and will need to return them to the 850-900 range using the big idle air bypass screw. If the idle rpms went up a lot (say above 1000 rpms) when you set the timing, you might double check the timing now that you have got the rpms back down (the mechanical advance may have advanced the timing on you). If the timing and rpms are good, you can reconnect the vacuum hose to the distributor, tighten the distributor clamp, and proceed to the next step.

Next step will be adjusting the small idle mixture screw. You will need to turn the screw SLOWLY to get the fastest idle speed (normally it is within a half turn of your initial position). I normally turn it a little bit and wait several seconds for the engine to react and settle out. Once you have the fastest idle speed, turn it in SLOWLY until the rpms drop ever so slightly (depending on your tachometer or hearing this may be hard to perceive). Small turns on the mixture screw can make surprising large changes. The turn from fastest to slight drop can be an 1/8 turn or less. This mixture setting is sometimes called lean best idle because it is very slightly lean of the fastest idle speed (it isn't actually lean - I have found it to be around 14:1 when I have used a wideband O2 sensor). Once the lean best idle mixture is set, you just need to adjust the big idle air bypass screw to bring the rpms back to 850-900 (again I aim more towards 900 - I will do 850 if I am setting the idle speed with electrical load like headlights on). After that you should be all set on the idle.

If you are finding that the idle screws on the side of the carburetor aren't adjusting like you expect, you may have a vacuum leak to chase down. Common ones include the o-rings on the adjustment screws themselves, the throttle bushings, the rubber boots on the intake manifold, and sometimes the manifold ends to head gaskets.


I'll make a side note on idle adjustment for those of us (like me) that are running the 34 PICT-3 with DVDA anda non-stock cam. The dance can be more involved than what I described above. The DVDA is timed with the hoses connected and your timing can vary depending on how strong your idle vacuum is. With a stock cam, the idle vacuum is normally good and you only end up setting the timing once (unless the rpms went above 1000 when you adjusted the timing). My engine (1835 with unknown non-stock cam - possibly engle w100) only gets good idle vacuum when the mixture and timing is exactly right, which can be maddening because if anything is off, the vacuum drops which messes with the mixture adjustment and changes the timing. The saving grace is that it is really obvious when I get it right.
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[Ozmello]

Not sure why the brace between the block and carburetor is there, Jim. The lower part of the brace fits over one of the fuel pump studs. I would assume it's a belt and suspenders thing.

Thanks for the informative post, Silver Thing. I've set static timing, adjusted the volume and bypass screws to their initial positions, and adjusted the throttle arm screw. I've also adjusted the choke. In this condition zero, and with the vacuum hose to the distributor pulled and blocked, I set the choke and then crank the ignition. The car starts fairly easily and then revs to around 2k rpm. At that point the timing, as read with a light, is about 20 degrees advanced. Retarding the timing brings the rpms down to around 1.4k. Adjusting the bypass screw has little effect. As the choke opens, the only way to keep the car running is to rev the engine. I have tried disconnecting the power from the choke so that I can open it slowly by hand, and while I am, at times, able to get the choke slightly open, the car eventually loads up and dies.

Tomorrow I am going to check other ignition settings and start again. Although it violates all the rules of troubleshooting I am thinking about getting a new carb and installing it. While that would introduce more variables to the problem, I think it elimnates more than it adds. If the forum has suggestions for the best aftermarket unit, I would appreciate the input. I am also considering an electronic ignition. Again, input is appreciated.

[SilverThing]

Just popped in my head: have you made sure your valves are adjusted correctly with the engine cold? That should be a minimum starting point. My experience is they have to be pretty far out of adjustment to mess with idle settings, but every little bit can help here.

Get the engine warmed up before you mess with any of the ignition or carb settings! Speaking from experience, you will be chasing your tail and will get very frustrated if you're trying to adjust things before it is warmed up. Let it warm up even if it is at 2k rpms for a little bit. Retarding the timing at 2k rpms might bring those rpms down, but it will likely work against you with trying to get it to idle. Firing the spark too late requires extra air at idle, which your initial settings probably don't have.

The key is to get it to warm up so that it will run without the choke richening the mixture and holding the throttle open. If it is still struggling to idle, you might adjust the initial settings to see if that helps (going to 3 turns instead of 2.5 for example).

Normally I wouldn't recommend replacing your carburetor until you know it is the problem, but it might not be the worst idea in this particular case. I really don't know how that carburetor behaves with the vacuum operated jets (and if the jets are even hooked up correctly). I don't know if any of the aftermarket stock carburetors are any good. I am running a rebushed factory carburetor from https://www.volkzbitz.com/ and am pleased with it. https://www.sparxwerks.com/shop would be where I would be looking for a distributor.

On distributors: I know that a lot of folks go for points replacement modules like pertronix or one of the many similar products so that they don't have to adjust points, which is admittedly a fiddly thing. I have not personally had good luck with those electronic modules, though. I have been left stranded by them randomly on multiple occasions and have never felt that they have given me my money's worth. I have gotten many more miles out of a set of points and condenser than I have ever gotten out of one of the electronic modules (one set of points ran in my bug for 32k miles without failure). Points generally give warning of rough running before they completely fail on you. The one exception I had was the wire on a set of points themselves broke once, which was a sudden unexpected failure, but that was very much a one-off. Right now, I run points as a trigger for an electronic unit (specifically a 70s period-correct, dealer accessory 'Autobahn' Permatune CDI). That way if the electronic unit fails, I can still get home on the old fashioned points and condenser. If you want a modern unit, I would recommend a Winterburn CDI http://capacitordischargeignition.com/9901.html. I have one for my Ghia and like the build quality. Fred Winterburn's dad invented the solid state CDI so there is a period connection, if you care about that.
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[VolkzBitz]

I would remove the vacuum hose shown in your last picture from the carburetor and cap it off, that port is for the DVDA distributor and your using an SVDA.
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[SilverThing]

Hey Volkzbitz, glad you could join us. Feel free to correct anything I might have gotten wrong in the previous posts.

The DVDA port looks like it is connected to the vacuum actuated main and pilot jets. Volkzbitz, do you have any experience with those jets? I don’t know how they behave and whether they would be contributing to Ozmello’s issues.
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"I've seen pictures..." - Jeremy

[VolkzBitz]

SilverThing, you seem to have got things correct. I believe that the jetting system on this carburetor is for emissions.

Ozmello, I would cap that port as I mentioned and also check your idle jet to make sure its clear, its located just below the choke and looks like a brass bolt with a screwdriver slot. Remove it and poke a thin wire through the end, replace and give it a go.
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[Ozmello]

I feel as though I made real progress yesterday; I was able to get the car to idle at 900ish rpm with the choke wide open and was able to stop and restart it with the choke open. I was confident enough that I decided to take the car for a spin, but backing out of the drive it died and wouldn't restart. I pushed it back under the house and started over again. Unfortunately, I had to go back north today and so the car will sit for another six weeks until I can get back to it, but I'm confident that I'm close to whipping the problem(s).

Tim, I haven't blocked the DVDA port yet, and was unable to find the jet below the choke, not even after looking at the pic's of carb's on your website. I'm thinking that the Mexican carb that I have is different enough that some of the advice that I'm receiving is not relevant. That said, I'll be reaching out to you to see if I can purchase a carb from you. I think that will at least allow me to use the references from this forum and the shop manual to help with getting the car set up.

[VolkzBitz]

Blocking / capping that port may make a big difference.

I totally forgot about the different style idle jet in the carburetor that you have, its actually under a large brass screw below the choke unit. Removing this type of idle jet would require removing the carburetor and using a small screwdriver to reach inside under the brass screw. You could just try shooting carb cleaner through it with it still in place.
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