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first adventure w snowtrac not so good

i would love to find another vaccuum advance distributor just for that reason, i do carry a spare carb and points as they are cheep and easy t replace i also carry a spare cap and rotor as i have had both fail in the past, great spark from the coil wire yet getting to the plugs at the wrong time or not at all. also a spare electric fuel pump rides along the mechanical one just plugs a hole as i have seen too many go bad and dilute the oil in the field.
 
Just a stupid question, but does anyone think it may be the fuel vent? The reason I ask is because I had a van back in the 80's that did the same thing..Run 5-6 minutes and die, wait a few minutes and it would start up and run for another 5-6 minutes and die again.
 
Tonights update
Snow trac is back home.

Problem was the distributor. Swapped in the loaner and static timed it. Engine fired right up, easier than ever before in fact barely had to bump the starter. Root problem was the spring broke on the weights on the advance mechanism. Once started idled smooth and behaved well. I have to give the loaner back but now I know.
It was a steep learning curve and now I'm going to use the others features of the pub. Night all
 
Good you got it running. Sounds like you need to hunt up a spare to have along. You know if you do you won't have ignition problems again.:yum:
 
well that distributor should be easy to repair now is the time to learn about setting it up with new points and condensor once you have done it once you will find it quite easy
 
forgot getting the right advance springs will be kind of voodo but you can usualy get a kit with several different typs of springs so you can taylor your cintrifugal advance to your driving conditions.
 
Congratulations on getting your rig home! In some ways this hasn't been the best introduction to snow cats, but you've certainly learned a lot more in the past few days than you would have if your trip had been trouble-free. Hopefully your next outing will be less educational.

Ron
 
Glad you got it home too! Always a few bugs to work out on a "new" 40 year old rig.
Where did you end up taking it to drive in the snow anyway? I am also in Oregon.
 
snowsurfer said:
Glad you got it home too! Always a few bugs to work out on a "new" 40 year old rig.
Where did you end up taking it to drive in the snow anyway? I am also in Oregon.
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I used to have a IH mini dump truck. That taught me a lot about old rigs. If the memory of keeping it running haden't faded I probably wouldn't have bought the st.

Goat Mt. East of mollala.
 
Cidertom said:
Tonights update
Snow trac is back home.

Problem was the distributor. Swapped in the loaner and static timed it. Engine fired right up, easier than ever before in fact barely had to bump the starter. Root problem was the spring broke on the weights on the advance mechanism.
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Cool! Glad you got it home without a tow. I am not surprise one of the springs was broken, but I would be surprised if that alone caused it to not run well and give the symptoms you experienced.

VW (Bosche) made so many distributors for that engine it isn't funny. Any air-cooled Type 1 distributor from the old 25hp made in the 1940's, thru the ones supplied as recently as the mexican beetles being produced up until 10 years ago or so, will work. If you want/need stellar off-idle throttle response, need the advance to 'come in gradually' like you would in a heavy VW bus, then finding a more modern distributor with single vacuum advance is what I would advise. Cheap and easy is to just buy what is referred to as a '009' distributor, that has mechanical advance only, plug the vacuum port on carb and be done with it. Driveability might suffer a little with mechanical advance only, as they go to 'full advance' rather quick and at relatively lower rpms (irrespective of engine load), but sometimes it's worth not having to maintain the vacuum diaphragm, which do go out, and depending on your distributor, can be tough to find these days.
 
TinTopTom said:
Man, that's my worst nightmare, stuck on some snow covered fire trail where it's real tough to get out. :doh:

I don't own a Snow-Trac yet, but I have 35yrs of VW experience. I hate to sound like some know-it-all, blow-hard, but if I don't mention my experience, my advice might be dismissed.
For troubleshooting an older carbureted and points ignition engine, don't under estimate the efficiency and power of having known good spares.

Spares: On every VW endurance en devour I've been on, we always carry what we lovingly refer to as our 'crash box', or a 'possibles box'. Included is a known good used distributor, fully set up with spark plug wires, numbered, that has been previously run and timmed on THAT engine. When I say set up and timed, I mean with the locking ring clamped in place that stays with the spare distributor. That way, the replacement distributor is truly plug-n-play with nothing more needed than a 13mm socket and extension, no fiddling with the clamp with cold fingers, no setting of timing or adjusting points, or swapping over possible bad ignition parts from old to replacement distributor. Same with a spare carb, run-in and adjusted for THAT engine, drained of it's gas and brought along is cheap insurance.

I hope you get it fixed on the trail, and can self-recover it. Good Luck!
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Good advice. I'm still learning this engine, but the spare distrib and carb is what I'm thinking. Also in that box is going to be a spare in line fuel filter, a spare electric fuel pump and the fuses to power the mandatory circuits. Perhaps plugs. At some point it gets insane (spare long block) but those parts are small enough to be carried easily. It might be different if I was running around with others, but I'm going back country with limited communications, and no one else around.
 
TinTopTom said:
Cool! Glad you got it home without a tow. I am not surprise one of the springs was broken, but I would be surprised if that alone caused it to not run well and give the symptoms you experienced.
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I have not dug into this much but one item I found
"Most all of the VW industrials had a unique spring loaded distributor rotor that prevented the engine from being over-reved. It was designed to ground out over a certain RPM. " (source of info: http://www.forumsforums.com/3_9/archive/index.php/t-8371.html "


So when the spring is broken perhaps it is acting as if it is over rev since any rotation would cause the weights to fly out as if they are spinning too fast. Don't know really but points, cap and wiring checked out. But the sub in of a new distrib solved the issue.
 
I misunderstood... I thought you had the distributor apart and found a broken mechanical advance spring. When those break, the distributor 'advances timing, at lower than intended RPM.

If you have a rev-limiting rotor, show in this ad:
http://www.thesamba.com/vw/classifieds/detail.php?id=1324659

I have little first hand experience with those, but if the rotor spring is broken, that is likely your culprit.

On rev-limiting rotors, by design, centrifugal force opens the contact at around 4500 engine rpm, 2250 distributor rpm, and the engine's ignition cuts out, until the engine slows, and the contact is 're-made'. One way to test the rotor on the bench, is with a simple volt-ohm meter. Touch the contact plate (center) with one lead, the other to the electrode near the edge. Open circuit on the bench, zero rpms, means the rotor is junk. Another method; Bosche made 10's if not hundreds of distributors that fit acvw's, but only a few cap and rotor types. it is possible to 'swap in' a non-rev limiting rotor, as a test. Some drag racers used to swap in the higher rev limiting rotor as a means not hurting the motor when a shift is missed (that's fallen out of favor, must guys, myself included, just use MSD ignition parts on our race cars these days).

Know that there are many options for replacement parts, you aren't confined to "VW Industrial engine only" parts lists. Here at work, we have liquid nitrogen delivered almost daily. Back in the 80's-early 90's many of the older LN trucks used industrial air-cooled VW engines, which theu were having trouble sourcing parts for. A buddy of mine took the time to cross reference parts and would sell them parts to maintain their fleet. Some even came with Sintila magnetos, I'm told.

There is a real good place north of you in Woodburn WA called Avery's Air-cooled that I recommend. Not your average parts-n-repair joint, Avery's owner, Todd I think his name is, manufactures his own line of race-grade VW engine cases. www.averysaircooled.com/ They could probably help set you up.
 
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the magnitos in those ac lng motors were they an impulse coupled magnito or just a streight mag. nothing i would like better than an impulse coupled magnito for my snow trac.
 
I miised the part about the limiter being in the rotor. I have a standard rotor in the unit. So that's not it. I'm going to bench spin the distributor and see what the advance does. If it goes to full advance too early (low RPM) I could see it not working well enough to keep the engine running long enough to get up to speed. I do know the points are good, gapped correctly. The capacitator checks good. The wiring was intact and not shorted. The unit was static timed. It ran badly and died quickly. The backfiring and flames out of the carb... On installing the known good (same cap, rotor) it started easier than before.

Oh well a learning curve to be sure.

Hope to have it back together this weekend.
 
dds said:
the magnitos in those ac lng motors were they an impulse coupled magnito or just a streight mag. nothing i would like better than an impulse coupled magnito for my snow trac.
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I don't know enough about magnetos to know the difference between impulse or non, I've never had the desire to use on on my own race cars. I crewed on a dragster that had a single, and another dragster that used dual 44amp magnetos, but those cars only use them because it takes a lot of fire to reliably ignite large volumes of alcohol and nitromethane. The system would throw an arc hot enough to bridge a 4" gap, 1/4" diameter (in air) :shock:

Airplane guys seem to swear by magnetos, most racers I know, have learned to swear at them :shifty:
 
The impulse type has a spring mechanism inside that "kicks" the armature in the mag to a high speed just as current is being devoloped to fire the plug. The result is a much hotter spark at cranking speeds. (think about hand cranking a car engine 75 years ago. You needed an advantage!) There is a clicking sound they make as the engine is being cranked as the spring unloads, drivng the armature faster...The mechanism stops it's action when the engine starts to get up to speed, and the magneto funtions as any other would then..

Regards, Kirk
 
TinTopTom said:
Cidertom, did you get it running reliably?
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Sort of: Took distrib apart. One spring gone, a piece of white plastic under the other weight. Troubling is the amount of damage on the bottom (underside)of the mounting plate. A lot of scaring and even a couple of large divots. When I was working the distributor it never came close, but obviously it has in the past. I chucked the distrib in the lathe, and the slightest movement took the advance to around 40 deg. The weight that sems to be the primary "closing" weight was the one that had the plastic wedged under it. Once it spun open, it required stopping the dist, and wiggling the shaft to get it back to 5 deg or so.

I pushed, plulled, twisted and could not get anything to duplicate the contact on the bottom of the plate. That worries me more than if I had found the issue.

Cleaned it well, relubed and it runs fine now.
 
Congrats cidertom. I had a similar problem couple weekends ago. Mine was closer only about 15 miles from my house, tried everything, rebuilt the carb, installed new rebuilt carb, replaced points, coil, cap, plugs, wires, fuel pump, even the starter while all in the mountains over a three day period. I just so happened to glance at your issues so I picked up a distributor and headed back up, installed and she ran perfect, had the same issues of it starting just a little but would run. So after three trips and swapping a couple batteries and numerous parts she was on her way hoe.

ameba5ez.jpg


Thanks for everyone's info.

Sent from my iPad using Tapatalk HD
 
Cidertom said:
Sort of: Took distrib apart. One spring gone, a piece of white plastic under the other weight. Troubling is the amount of damage on the bottom (underside)of the mounting plate. A lot of scaring and even a couple of large divots. When I was working the distributor it never came close, but obviously it has in the past. I chucked the distrib in the lathe, and the slightest movement took the advance to around 40 deg....
Click to expand...

Keep after it... you've almost got it! Once tune properly, these little engines are really good. There is no reason you can't get it to where starting is just dab the accelerator once to give it a fuel shot, hit the stater, and have it purrrr like a kitten :-)

I have a couple of comments;

1) These little engines will run, idle, not sputter and die, at 30deg advanced. My race engines all have there timing locked out at 30deg advanced, which is pretty common. I'm not suggesting you settle for locked full advance timing, driveability would suffer too much, but the symptoms you've described that lead up to you being stuck don't sound to me like a 'full advance too early' timing issue. Hard stating in the cold at 40deg advanced I would expect, but once fired up it would run at 1500 rpm, unless you have a series of other problems along with it.

2) Distributors for air-cooled VW's are, in the big scheme of things, are a dime-a-dozen, and dead-simple devices. If it were me faced with a poor running engine and a beat up distributor unit, I wouldn't hesitate to just get a good used one (with non-wore out shaft bearings and snug points plate, good springs, etc) and rebuild it with new ignition parts and vacuum diaphragm, or buy a new one, and put it in. Done. Unlike most American distributors, air-cooled VW distributors are easy to swap out as they only go in one way. The distributor drive gear is offset, so the drive tangs will only engage one way out of 360deg. I think John Muir's 'Idoit Book' has a great description with sketches of this, but the holy grail of all VW repair manuals is the factory endorsed 'Bently Manual' for a similar year beetle.

3) Tune up: I do this , in this order. Change oil and adjust the valves. Give a quick compression test. A tight valve will cause popping thru the carb, and you'll never get it to run right, a badly burned valve will show itself with a quick comp test. New Bosche copper plugs with copper-dopped anti-seize, inspect plug wires with Volt-Ohm Meter (VOM) for <1,000 ohms/foot. Tune up the distributor on the bench (inspect, set gap, new parts as needed), re-instal (new dist. o-ring if leaking), start and set timing w/strobe-type timing light checking for smooth timing advance operation, both intital low rpm advance, and high rpm full advance timing, Making sure after reving the advance returns to initial idle advance setting. Check carburetor operation; Accelerator pump squirting, choke operation cold and hot, making sure element is getting power and hot. Set idle mixture, and last, idle rpm.
 
A quick way to isolate your problem is to spray some flammable liquid [brake or carb cleaner] down the carb throat and crank it. If it fires for a second and dies your problem is either fuel supply or carb. If it doesn't your problem is ignition. The electronic ignitions fail frequently and are expensive to replace. Points are cheap. Carry a spare. Allways use the Robert Bosch points. One common problem with points on VW's is they stick. Allways take them apart by pinching the arm and spring together and removing it from the pivot. Put a thin film of oil on the pivot shaft and reassemble. Also put point grease on the cam rubbing block.. It sounds like you have decent fuel supply. Loosing your accelerator nozzle will not cause it to stop running but will give a hesitation. If there is good spark you may have a plugged main jet in the carb. Remove the plug on the bowl [left hand side of carb].If and inch or more of fuel doesn't come out you may have a plugged needle and seat. Remove the top and replace it. If fuel comes out remove the pilot jet [upper right hand side of carb]. Spray carb or brake cleaner with a nozzle into the bowl to wash the debris out. Next spray into the hole the pilot jet came out of. The main jet is straight back in the hole where the plug was. Spray lots of cleaner into the hole in the jet. Your missing nozzle can be purchased separately and replaced by removing the top of the carb. Before you tap the nozzle down to secure it work the throttle and move the nozzle to direct the spray in the space between the back of the carb and the butterfly. Good Luck.. Beck
 
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