VW Beetle Custom & Performance
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The VW Transmission
I first started working on VW transmissions about 15 years ago. Before that, I was constantly tearing them out, and replacing them only to find the one I put in was not much better than the one I took out, sometimes even worse. So I started to work on them myself. There are a lot of differences between all of the types that VW has used all through the years, and usually, with each change, some improvements were made. This page WILL be most of my knowledge about VW transmissions, and the differences and good vs bad in them. If you are looking for someone to build one for you, then maybe I can help. I can build anything you want from as mild or as wild as you want. If you just want advice, or are wanting to learn to do it yourself, then I am here for that as well. If you have any questions, or need any parts, gears, ring and pinions, etc., f
I first started working on VW transmissions about 15 years ago. Before that, I was constantly tearing them out, and replacing them only to find the one I put in was not much better than the one I took out, sometimes even worse. So I started to work on them myself. There are a lot of differences between all of the types that VW has used all through the years, and usually, with each change, some improvements were made. This page WILL be most of my knowledge about VW transmissions, and the differences and good vs bad in them. If you are looking for someone to build one for you, then maybe I can help. I can build anything you want from as mild or as wild as you want. If you just want advice, or are wanting to learn to do it yourself, then I am here for that as well. If you have any questions, or need any parts, gears, ring and pinions, etc., f
The VW Transmission
I first started working on VW transmissions about 15 years ago. Before that, I was constantly tearing them out, and replacing them only to find the one I put in was not much better than the one I took out, sometimes even worse. So I started to work on them myself. There are a lot of differences between all of the types that VW has used all through the years, and usually, with each change, some improvements were made. This page WILL be most of my knowledge about VW transmissions, and the differences and good vs bad in them. If you are looking for someone to build one for you, then maybe I can help. I can build anything you want from as mild or as wild as you want. If you just want advice, or are wanting to learn to do it yourself, then I am here for that as well. If you have any questions, or need any parts, gears, ring and pinions, etc., f
I first started working on VW transmissions about 15 years ago. Before that, I was constantly tearing them out, and replacing them only to find the one I put in was not much better than the one I took out, sometimes even worse. So I started to work on them myself. There are a lot of differences between all of the types that VW has used all through the years, and usually, with each change, some improvements were made. This page WILL be most of my knowledge about VW transmissions, and the differences and good vs bad in them. If you are looking for someone to build one for you, then maybe I can help. I can build anything you want from as mild or as wild as you want. If you just want advice, or are wanting to learn to do it yourself, then I am here for that as well. If you have any questions, or need any parts, gears, ring and pinions, etc., f
i'm thinking of building my own bug (buy one, strip it, and rebuild)..this tecnical thread sure help a lot on adding knowledge for me b4 i commence my project..
There Are Four Different Ignition Systems
You Can Use On a VW
1. The Stock Points/Condensor System. Works okay, but the voltage at the plugs gradually drops as the rpm increases (this happens with all points/condensor systems) and the points will also start to "float" at very high rpm. The plugs get about 18,000 volts. The points wear fast because they have to switch about 5 amps, and so they spark. The condensor reduces the sparking but it still happens so the points wear out (burn). The spark also slows down the switching process, so the coil gets a "soft" switch and the resulting plug voltage is a little less than it could be. (The coil produces the high voltage to the plugs when the points open and the magnetic field inside the coil collapses. The faster you can cut the power to the coil the faster that field collapses so the better the plug voltage).
2. The Pertronix/Compufire Points Replacement Modules. These replace the points with a hall-effect sensor or (in some earlier models) an optical sensor. They electronically switch the power to the normal coil, so the coil is still working at 12 volts (but the elecronic switching is faster than the sparking points so coil performance is a little better). The plugs get about the same 18-20,000 volts. These points replacement units don't wear so your timing stays very steady and doesn't need adjusting much.
3. Transistor-Assisted Ignition. These use a very small current through the points to switch a power transistor on and off (imagine the power transistor as an electronic relay - using a small current to switch a bigger current) and the power transistor supplies a normal 12 volts to the coil. But like the Pertronix it provides faster switching than sparking points can, so coil performance is a little better than stock - still in the 18-20,000 volts range to the plugs though. The points last a long time as they don't spark any more - only a tiny trigger current flows through them. These systems are not very common these days, but will work well, and are easy to build. You could consider these sytems as a cheap alternative (but roughly equivalent) to the Pertronix/Compufire.
4. Capacitance Discharge Ignition (CDI). This can be triggered by systems #1 or #2 above, but is not used in conjunction with system #3 at all. (Consider it as a BOOSTED #3). The CDI system has a couple of very large capacitors continously charging from a high frequency circuit using a "toroid" (donut shaped) transformer inside the unit (the high frequency produces the characteristic whine like a camera flash charging up) and when the points or the Pertronix triggers it, the capacitors dump about 400 volts through the coil, so you get about 40,000 volts out of it for the plugs, rather than the normal 18-20,000v. This provides a thinner but much hotter spark which will light a weak or rich mixture, so you get easier starting, and you also get slightly better economy, and your plugs last longer. And of course - if you use it with the normal points, the points will last a long time because they are only providing a small trigger current - the capacitors are providing the main pulse to the coil. You can open the plug gap a little with a CDI - for a longer spark. Up to about 0.045", but if you set it at 0.035" you can forget the plugs for many thousands of miles - the electrodes with still burn away slowly, but won't go "over gapped" because you started with a modest increase. One useful feature of POINTs fired CDIs is that they can be used to upgrade the ignition on early VW engines and still retain the retarded #3 ignition which is needed for the non-doghouse engines.
MSD is usually a variation of the CDI - providing a multi-spark rather than a single spark.
There are also magnetos which will fit the VW engine - these are self contained ignition systems - no battery is needed, and are sometimes used in VW aircraft engines.
You Can Use On a VW
1. The Stock Points/Condensor System. Works okay, but the voltage at the plugs gradually drops as the rpm increases (this happens with all points/condensor systems) and the points will also start to "float" at very high rpm. The plugs get about 18,000 volts. The points wear fast because they have to switch about 5 amps, and so they spark. The condensor reduces the sparking but it still happens so the points wear out (burn). The spark also slows down the switching process, so the coil gets a "soft" switch and the resulting plug voltage is a little less than it could be. (The coil produces the high voltage to the plugs when the points open and the magnetic field inside the coil collapses. The faster you can cut the power to the coil the faster that field collapses so the better the plug voltage).
2. The Pertronix/Compufire Points Replacement Modules. These replace the points with a hall-effect sensor or (in some earlier models) an optical sensor. They electronically switch the power to the normal coil, so the coil is still working at 12 volts (but the elecronic switching is faster than the sparking points so coil performance is a little better). The plugs get about the same 18-20,000 volts. These points replacement units don't wear so your timing stays very steady and doesn't need adjusting much.
3. Transistor-Assisted Ignition. These use a very small current through the points to switch a power transistor on and off (imagine the power transistor as an electronic relay - using a small current to switch a bigger current) and the power transistor supplies a normal 12 volts to the coil. But like the Pertronix it provides faster switching than sparking points can, so coil performance is a little better than stock - still in the 18-20,000 volts range to the plugs though. The points last a long time as they don't spark any more - only a tiny trigger current flows through them. These systems are not very common these days, but will work well, and are easy to build. You could consider these sytems as a cheap alternative (but roughly equivalent) to the Pertronix/Compufire.
4. Capacitance Discharge Ignition (CDI). This can be triggered by systems #1 or #2 above, but is not used in conjunction with system #3 at all. (Consider it as a BOOSTED #3). The CDI system has a couple of very large capacitors continously charging from a high frequency circuit using a "toroid" (donut shaped) transformer inside the unit (the high frequency produces the characteristic whine like a camera flash charging up) and when the points or the Pertronix triggers it, the capacitors dump about 400 volts through the coil, so you get about 40,000 volts out of it for the plugs, rather than the normal 18-20,000v. This provides a thinner but much hotter spark which will light a weak or rich mixture, so you get easier starting, and you also get slightly better economy, and your plugs last longer. And of course - if you use it with the normal points, the points will last a long time because they are only providing a small trigger current - the capacitors are providing the main pulse to the coil. You can open the plug gap a little with a CDI - for a longer spark. Up to about 0.045", but if you set it at 0.035" you can forget the plugs for many thousands of miles - the electrodes with still burn away slowly, but won't go "over gapped" because you started with a modest increase. One useful feature of POINTs fired CDIs is that they can be used to upgrade the ignition on early VW engines and still retain the retarded #3 ignition which is needed for the non-doghouse engines.
MSD is usually a variation of the CDI - providing a multi-spark rather than a single spark.
There are also magnetos which will fit the VW engine - these are self contained ignition systems - no battery is needed, and are sometimes used in VW aircraft engines.
There Are Four Different Ignition Systems
You Can Use On a VW
1. The Stock Points/Condensor System. Works okay, but the voltage at the plugs gradually drops as the rpm increases (this happens with all points/condensor systems) and the points will also start to "float" at very high rpm. The plugs get about 18,000 volts. The points wear fast because they have to switch about 5 amps, and so they spark. The condensor reduces the sparking but it still happens so the points wear out (burn). The spark also slows down the switching process, so the coil gets a "soft" switch and the resulting plug voltage is a little less than it could be. (The coil produces the high voltage to the plugs when the points open and the magnetic field inside the coil collapses. The faster you can cut the power to the coil the faster that field collapses so the better the plug voltage).
2. The Pertronix/Compufire Points Replacement Modules. These replace the points with a hall-effect sensor or (in some earlier models) an optical sensor. They electronically switch the power to the normal coil, so the coil is still working at 12 volts (but the elecronic switching is faster than the sparking points so coil performance is a little better). The plugs get about the same 18-20,000 volts. These points replacement units don't wear so your timing stays very steady and doesn't need adjusting much.
3. Transistor-Assisted Ignition. These use a very small current through the points to switch a power transistor on and off (imagine the power transistor as an electronic relay - using a small current to switch a bigger current) and the power transistor supplies a normal 12 volts to the coil. But like the Pertronix it provides faster switching than sparking points can, so coil performance is a little better than stock - still in the 18-20,000 volts range to the plugs though. The points last a long time as they don't spark any more - only a tiny trigger current flows through them. These systems are not very common these days, but will work well, and are easy to build. You could consider these sytems as a cheap alternative (but roughly equivalent) to the Pertronix/Compufire.
4. Capacitance Discharge Ignition (CDI). This can be triggered by systems #1 or #2 above, but is not used in conjunction with system #3 at all. (Consider it as a BOOSTED #3). The CDI system has a couple of very large capacitors continously charging from a high frequency circuit using a "toroid" (donut shaped) transformer inside the unit (the high frequency produces the characteristic whine like a camera flash charging up) and when the points or the Pertronix triggers it, the capacitors dump about 400 volts through the coil, so you get about 40,000 volts out of it for the plugs, rather than the normal 18-20,000v. This provides a thinner but much hotter spark which will light a weak or rich mixture, so you get easier starting, and you also get slightly better economy, and your plugs last longer. And of course - if you use it with the normal points, the points will last a long time because they are only providing a small trigger current - the capacitors are providing the main pulse to the coil. You can open the plug gap a little with a CDI - for a longer spark. Up to about 0.045", but if you set it at 0.035" you can forget the plugs for many thousands of miles - the electrodes with still burn away slowly, but won't go "over gapped" because you started with a modest increase. One useful feature of POINTs fired CDIs is that they can be used to upgrade the ignition on early VW engines and still retain the retarded #3 ignition which is needed for the non-doghouse engines.
MSD is usually a variation of the CDI - providing a multi-spark rather than a single spark.
There are also magnetos which will fit the VW engine - these are self contained ignition systems - no battery is needed, and are sometimes used in VW aircraft engines.
You Can Use On a VW
1. The Stock Points/Condensor System. Works okay, but the voltage at the plugs gradually drops as the rpm increases (this happens with all points/condensor systems) and the points will also start to "float" at very high rpm. The plugs get about 18,000 volts. The points wear fast because they have to switch about 5 amps, and so they spark. The condensor reduces the sparking but it still happens so the points wear out (burn). The spark also slows down the switching process, so the coil gets a "soft" switch and the resulting plug voltage is a little less than it could be. (The coil produces the high voltage to the plugs when the points open and the magnetic field inside the coil collapses. The faster you can cut the power to the coil the faster that field collapses so the better the plug voltage).
2. The Pertronix/Compufire Points Replacement Modules. These replace the points with a hall-effect sensor or (in some earlier models) an optical sensor. They electronically switch the power to the normal coil, so the coil is still working at 12 volts (but the elecronic switching is faster than the sparking points so coil performance is a little better). The plugs get about the same 18-20,000 volts. These points replacement units don't wear so your timing stays very steady and doesn't need adjusting much.
3. Transistor-Assisted Ignition. These use a very small current through the points to switch a power transistor on and off (imagine the power transistor as an electronic relay - using a small current to switch a bigger current) and the power transistor supplies a normal 12 volts to the coil. But like the Pertronix it provides faster switching than sparking points can, so coil performance is a little better than stock - still in the 18-20,000 volts range to the plugs though. The points last a long time as they don't spark any more - only a tiny trigger current flows through them. These systems are not very common these days, but will work well, and are easy to build. You could consider these sytems as a cheap alternative (but roughly equivalent) to the Pertronix/Compufire.
4. Capacitance Discharge Ignition (CDI). This can be triggered by systems #1 or #2 above, but is not used in conjunction with system #3 at all. (Consider it as a BOOSTED #3). The CDI system has a couple of very large capacitors continously charging from a high frequency circuit using a "toroid" (donut shaped) transformer inside the unit (the high frequency produces the characteristic whine like a camera flash charging up) and when the points or the Pertronix triggers it, the capacitors dump about 400 volts through the coil, so you get about 40,000 volts out of it for the plugs, rather than the normal 18-20,000v. This provides a thinner but much hotter spark which will light a weak or rich mixture, so you get easier starting, and you also get slightly better economy, and your plugs last longer. And of course - if you use it with the normal points, the points will last a long time because they are only providing a small trigger current - the capacitors are providing the main pulse to the coil. You can open the plug gap a little with a CDI - for a longer spark. Up to about 0.045", but if you set it at 0.035" you can forget the plugs for many thousands of miles - the electrodes with still burn away slowly, but won't go "over gapped" because you started with a modest increase. One useful feature of POINTs fired CDIs is that they can be used to upgrade the ignition on early VW engines and still retain the retarded #3 ignition which is needed for the non-doghouse engines.
MSD is usually a variation of the CDI - providing a multi-spark rather than a single spark.
There are also magnetos which will fit the VW engine - these are self contained ignition systems - no battery is needed, and are sometimes used in VW aircraft engines.
Regarding Electronic Ignition
If you want to make it last forever, or at least longer than the 70,000 or so it normally lasts, get rid of the points. Opening the points represents as asymmetric load on the distributor. Opening the points is the major cause for wear on the shaft and bushings. So get rid of them. Use a Pertronix unit. No load on the distributor shaft. Runs concentrically. Vastly reduces the wear-rate which is already pretty low because the distributor only turns at one-half engine speed. (Don't use an optically triggered unit. The Pertronix is magnetic.)
Buy a Pertronix 'Ignitor' that fits your distributor. Pull the distributor and install the 'Ignitor'. Be careful of the wiring. One lead is +12v, the other is the signal lead... it goes to the coil's negative terminal. The ground is internal through the body of the distributor.
Be sure to set the proper air gap and make sure the Hall effect sensor (the black epoxy cube on the aluminum plate) is standing square to the plate. I've installed several of these and most were bent right out of the box due to improper riveting. Easy enough to straighten but if you don't notice it the thing can actually rub against the magnet ring... not a good idea. (And yes, it's 'magnet' not 'magnetic'. There are four high-strength magnets cast into the nylon (?) ring that fits down over the cam lobes of the distributor shaft.)
Make sure the magnet ring is pressed FULLY down onto the cam lobes. There are instructions with the Ignitor but the illustrations don't look much like the real thing.
Put the rotor back on. (You can expect to wear out a rotor about every two years due to the higher spark voltage. Just carry a spare so it won't leave you stranded. Ditto for the cap.) Make sure the ROTOR seats fully. On some distributors, you can't use the 'Ignitor' because the magnet ring prevents the rotor from seating full depth. (But you can machine a bit off the lower edge of the rotor, if you're careful doing it.)
Fire it up. Hey! Now THAT's a difference. Reason is,you've just eliminated a lot of mechanical jitter that is present in most old distributors. The jitter is still there but the triggering method used by the 'Ignitor' masks it. No more points bounce. In fact, no more points, period. Your plugs are now being fired in response to an electronic signal that is far, far more precise than any mechanical switching arrangement.
Slap a strobe on that puppy. And plug a sniffer up the tail pipe -- you can lean that thing down by quite a bit, now that you've got a higher spark voltage. Static timing okay? Then go ahead and kick it up to where the advance is all in and check the max. Dial it back down to thirty degrees or less. (I run 28. Yeah, I know. But I'm more concerned with getting there than how fast I can get there.) Hot weather, bad gas, heavy load, crank it back a bit more. And tweak your idle down better ignition has caused your idle rpm to increase. Keep them between 800 and 900 rpm. Any slower and the engine won't cool properly when you come off the freeway, etc.
Now here's what's gonna happen. Your mileage is going to take a nice jump. Most folks report an improvement of 8 to 15 percent. Depending on how much you drive, that alone will pay for the mods in about two years. But the driving! Damn! The thing really DOES run better! That's because you've gotten rid of points-bounce and shaft-jitter and incomplete combustion at higher rpms. And that means your engine will last a little longer because your oil is going to stay a little cleaner because there won't be so many unburned hydrocarbons in the blow-by that gets into the crankcase.
Plus it's going to start better. A LOT better. And no more cross firing during damp weather. And your engine is running cooler, too! Those Corvair-type air seals really make a difference.
I've been using such an ignition system for nearly thirty years -- it's been available that long. I first wrote about it on the internet more than five years ago... and immediately got a blizzard of flamers and hate mail -- lots of kiddies shouting 'If it's really that good and really that easy, then why haven't we seen anything about it in the magazines?'
If you want to make it last forever, or at least longer than the 70,000 or so it normally lasts, get rid of the points. Opening the points represents as asymmetric load on the distributor. Opening the points is the major cause for wear on the shaft and bushings. So get rid of them. Use a Pertronix unit. No load on the distributor shaft. Runs concentrically. Vastly reduces the wear-rate which is already pretty low because the distributor only turns at one-half engine speed. (Don't use an optically triggered unit. The Pertronix is magnetic.)
Buy a Pertronix 'Ignitor' that fits your distributor. Pull the distributor and install the 'Ignitor'. Be careful of the wiring. One lead is +12v, the other is the signal lead... it goes to the coil's negative terminal. The ground is internal through the body of the distributor.
Be sure to set the proper air gap and make sure the Hall effect sensor (the black epoxy cube on the aluminum plate) is standing square to the plate. I've installed several of these and most were bent right out of the box due to improper riveting. Easy enough to straighten but if you don't notice it the thing can actually rub against the magnet ring... not a good idea. (And yes, it's 'magnet' not 'magnetic'. There are four high-strength magnets cast into the nylon (?) ring that fits down over the cam lobes of the distributor shaft.)
Make sure the magnet ring is pressed FULLY down onto the cam lobes. There are instructions with the Ignitor but the illustrations don't look much like the real thing.
Put the rotor back on. (You can expect to wear out a rotor about every two years due to the higher spark voltage. Just carry a spare so it won't leave you stranded. Ditto for the cap.) Make sure the ROTOR seats fully. On some distributors, you can't use the 'Ignitor' because the magnet ring prevents the rotor from seating full depth. (But you can machine a bit off the lower edge of the rotor, if you're careful doing it.)
Fire it up. Hey! Now THAT's a difference. Reason is,you've just eliminated a lot of mechanical jitter that is present in most old distributors. The jitter is still there but the triggering method used by the 'Ignitor' masks it. No more points bounce. In fact, no more points, period. Your plugs are now being fired in response to an electronic signal that is far, far more precise than any mechanical switching arrangement.
Slap a strobe on that puppy. And plug a sniffer up the tail pipe -- you can lean that thing down by quite a bit, now that you've got a higher spark voltage. Static timing okay? Then go ahead and kick it up to where the advance is all in and check the max. Dial it back down to thirty degrees or less. (I run 28. Yeah, I know. But I'm more concerned with getting there than how fast I can get there.) Hot weather, bad gas, heavy load, crank it back a bit more. And tweak your idle down better ignition has caused your idle rpm to increase. Keep them between 800 and 900 rpm. Any slower and the engine won't cool properly when you come off the freeway, etc.
Now here's what's gonna happen. Your mileage is going to take a nice jump. Most folks report an improvement of 8 to 15 percent. Depending on how much you drive, that alone will pay for the mods in about two years. But the driving! Damn! The thing really DOES run better! That's because you've gotten rid of points-bounce and shaft-jitter and incomplete combustion at higher rpms. And that means your engine will last a little longer because your oil is going to stay a little cleaner because there won't be so many unburned hydrocarbons in the blow-by that gets into the crankcase.
Plus it's going to start better. A LOT better. And no more cross firing during damp weather. And your engine is running cooler, too! Those Corvair-type air seals really make a difference.
I've been using such an ignition system for nearly thirty years -- it's been available that long. I first wrote about it on the internet more than five years ago... and immediately got a blizzard of flamers and hate mail -- lots of kiddies shouting 'If it's really that good and really that easy, then why haven't we seen anything about it in the magazines?'
The History of the 009
Centrifugal-Advance Distributor
VW built a lot of industrial engines (called Type 122 for the 1200cc and Type 124 for the 1600cc engines), as well as those built for the Beetle itself. Industrial engines powering generators, compressors and such run at near constant speed, so only a simple distributor was needed. For this application, a centrifugal-advance distributor was developed by VW and later by Bosch. This type of distributor increases the amount of advance as the engine speed rises, but can not sense the throttle position (engine load). This is fine for engines operating at constant speeds, or at high power and high rpm (for VW racing engines for example, plus the previously-mentioned industrial engines).
When the first Type 2 (Kombi etc.) vehicles came out (about 1954), they used the 1200cc VW engine and needed reduction hubs so that the tiny engine could push a heavy vehicle (with a top speed of about 85kmh since the reduction hubs meant it was revving it's heart out!).
Because the engines in the Type 2 were working at high rpm and high throttle most of their life, the VW version of the centrifugal-advance distributor was used on them too (but just try getting one off the line - they needed a lot of revs and clutch slip to avoid bogging down).
Most engines in road vehicles operate at various engine speeds and load conditions, which require a lot of variation in the amount of advance needed for optimum engine performance and economy. Ideally, the amount of advance varies from about 7 degrees to a maximum of about 42 degrees, depending on the engine model and its intended use.
So most road vehicles use vacuum sensing, or a combination of vacuum and centrifugal, to get the best timing over a wide range of engine operations -- low throttle low rpm, low throttle high rpm, high throttle high rpm and every variation in between.
The early Beetles used single-vacuum distributors (SVSA). Then in 1971 VW introduced the double-advance distributor -- using both rpm-related and vacuum-related advance. The first US model of this distributor was the '71-'73 double vacuum distributor (produced to meet emissions requirements) called the DVDA. In other parts of the world a single-vacuum dual-advance (SVDA) was used. From 1974 onwards the U.S. also went to the SVDA. The SVDA distributor works like a high quality 009 distributor with added vacuum advance.
These distributors are quite expensive to build in comparison with the Bosch 009 distributors (the Bosch equivalent of the VW centrifugal distributor). So the cheap-to-build Bosch 009 distributor became the "one size fits all" replacement distributor, since it IS cheap and it does work moderately well. But precisely because the 009 is a "one-size-fits-all" distributor, it is NOT ideal for most engines, and it can cause problems for some engine/carburettor combinations.
To accelerate an engine smoothly, you need both extra fuel and an extra advance. The accelerator pump provides the extra fuel and the vacuum distributors provide the additional advance needed. But an 009 distributor cannot provide any advance until AFTER the engine rpm starts to increase (the advance starts happening at around 1200-1300 rpm) so, if the carburettor is set to run a little lean (LESS fuel), you get stumbline or hesitation (a "flat spot") which usually means the driver has to blip the throttle a time or two to get the rpm up to the point where the 009 distributor is starting to advance, then "feather" the throttle (and slip the clutch) so the rpm stays high, to avoid that flat spot.
The most common technique to overcome the flat spot associated with the 009 distributor is to replace that "missing" advance with extra fuel - a larger main jet, maximum stroke on the accelerator pump, and in some cases filling in the air-bleed hole in the throttle butterfly. By running the engine richer than normal throughtout its operation, the flat spot is minimised.
The earlier Solex carburettors (28PCI, 28PICT and 30PICT/1 and /2) are set to run a little on the rich side (the VW engine actually likes around 13.8:1 air/fuel ratio, where the ideal is 14.5:1). So since these carburettors are set to run rich anyway, the flat spot is often not noticable, or can be tuned out with minor adjustments.
But in 1970/71 the emissions problem was becoming recognised, and VW changed the jetting on the 30PICT/3 (1970 US only) and the 34PICT/3, and /4 to run the carburettor leaner - closer to the ideal 14.5:1 air/fuel ratio (the California 34PICT/4 used especially lean jetting and a throttle positioner to ensure that the throttle closed slowly after you lifted your foot off the pedal). So with this leaner running carburettor set-up, the 009 distributor flat spot becomes a real issue.
You'll hear most complaints from folks who use the 34PICT/3, 34PICT/4 or the modern equivalent for the smaller carburettors - the Brosol H30/31 (which is almost identical to the 1970 30PICT/3) - all of which normally come with lean jetting.
Another issue with the 009 distributor is the limited maximum advance. The vacuum distributors can run up to a maximum of about 40-42 degrees under the right conditions (light throttle and medium speeds for example) and this helps fuel economy. But if you maintained that much advance with a full throttle and low/medium rpm, the engine would ping/detonate, a problem which can destroy an engine if not corrected. The reason is rather technical, but is mainly related to the amount of residual exhaust gases which are left in the cylinder compared to the incoming charge. There is always SOME residual gas, since there's a head space above the cylinder. At part throttle there is a proportionally larger amount of burned gases in comparison to the fresh stuff (throttled fresh mixture but same head space of burned gasses). At full throttle there's a lower proportion of burned gases because you are letting in MORE fresh mixture for the fixed volume of head space. This "contamination" of the fresh mixture alters the flame speed (the time it takes for the fuel/air mixture to burn) so open-throttle needs less advance (burns faster) and part-throttle needs more advance (burns slower) at any particular rpm.
Incidentally, this is part of the reason why the low compression 1200cc engines need more advance - usually 10BTDC compared to 7.5 BTDC for most 1500/1600cc engines. Low compression means more head space (compared to the cylinder volume), and so there is more contamination of the fresh charge throughout the rpm range, and that means a little more advance is needed so all the fuel is burned just as the piston starts it's descent.
There is an rpm-related issue, too. As the engine rpm increases, the spark needs to occur sooner (more advance) to make sure the maximum pressure on the piston occurs just as it starts its descent.
The vacuum distributor senses throttle position, so if you floor the throttle at low-medium speeds, the distributor is able to "back off" the advance until the engine speed catches up with the new throttle position (slowly allowing the extra advance back in as the rpm/airflow rises). The 009 distributor can't do this, so it HAS to be set to "worst case," which is a maximum advance of between 28 and 32 degrees at 2500-2600 rpm (which is why we set the 009 distributor at 3000rpm - to make sure that all the advance is present).
Since the 009 distributor has been limited to a maximum advance of 28-32 degrees compared to the vacuum distributor's maximum advance of 40-42 degrees, it's actually under-advanced for a lot of driving conditions, and this means worse fuel economy. And because you need to set the carburettor to run rich to reduce the flat spots, fuel economy suffers even more.
Because the 009 distributor is built very cheaply, the total amount of advance varies from one distributor to the next. This means that when setting the 009 distributor, it's important to set it at maximum rpm, not idle, since the maximum advance is much more important for most engine conditions. Always use as much of the maximum advance of 28-32 degrees as the engine can take without pining/detonating, as this will reduce any flat spots just a little, and also help fuel economy just a little. If it still pings at a maximum advance of 28 degrees, always use a higher octane fuel. NEVER use less than a maximum advance of 28 degrees because it means the engine is seriously under-advanced at higher rpm and will run hotter than it needs to, and fuel economy will suffer as well.
In the heavier-bodied Kombi/Bus and Karmann Ghia vehicles, you might need to limit the maximum advance to the 28-30 degree range. These engines are less likely to tolerate the 32 degree maximum advance, as they are driven with more throttle to accelerate the heavier body.
Once you have determined the maximum advance which works well for your 009 distributor, you can then measure the idle advance (which will probably be between 5 and 10 BTDC but might be outside that range). If you want to, you can then use THAT timing setting for THAT 009 distributor, set either at idle or statically.
So you can see that the 009 distributor is NOT ideal, but it will work. For best performance under all engine operating conditions, we recommend using a vacuum distributor.
Hope all that makes sense.
There are Tune-up Articles on our Web site which include info on both vacuum and 009 distributor settings.
* * * * *
Centrifugal-Advance Distributor
VW built a lot of industrial engines (called Type 122 for the 1200cc and Type 124 for the 1600cc engines), as well as those built for the Beetle itself. Industrial engines powering generators, compressors and such run at near constant speed, so only a simple distributor was needed. For this application, a centrifugal-advance distributor was developed by VW and later by Bosch. This type of distributor increases the amount of advance as the engine speed rises, but can not sense the throttle position (engine load). This is fine for engines operating at constant speeds, or at high power and high rpm (for VW racing engines for example, plus the previously-mentioned industrial engines).
When the first Type 2 (Kombi etc.) vehicles came out (about 1954), they used the 1200cc VW engine and needed reduction hubs so that the tiny engine could push a heavy vehicle (with a top speed of about 85kmh since the reduction hubs meant it was revving it's heart out!).
Because the engines in the Type 2 were working at high rpm and high throttle most of their life, the VW version of the centrifugal-advance distributor was used on them too (but just try getting one off the line - they needed a lot of revs and clutch slip to avoid bogging down).
Most engines in road vehicles operate at various engine speeds and load conditions, which require a lot of variation in the amount of advance needed for optimum engine performance and economy. Ideally, the amount of advance varies from about 7 degrees to a maximum of about 42 degrees, depending on the engine model and its intended use.
So most road vehicles use vacuum sensing, or a combination of vacuum and centrifugal, to get the best timing over a wide range of engine operations -- low throttle low rpm, low throttle high rpm, high throttle high rpm and every variation in between.
The early Beetles used single-vacuum distributors (SVSA). Then in 1971 VW introduced the double-advance distributor -- using both rpm-related and vacuum-related advance. The first US model of this distributor was the '71-'73 double vacuum distributor (produced to meet emissions requirements) called the DVDA. In other parts of the world a single-vacuum dual-advance (SVDA) was used. From 1974 onwards the U.S. also went to the SVDA. The SVDA distributor works like a high quality 009 distributor with added vacuum advance.
These distributors are quite expensive to build in comparison with the Bosch 009 distributors (the Bosch equivalent of the VW centrifugal distributor). So the cheap-to-build Bosch 009 distributor became the "one size fits all" replacement distributor, since it IS cheap and it does work moderately well. But precisely because the 009 is a "one-size-fits-all" distributor, it is NOT ideal for most engines, and it can cause problems for some engine/carburettor combinations.
To accelerate an engine smoothly, you need both extra fuel and an extra advance. The accelerator pump provides the extra fuel and the vacuum distributors provide the additional advance needed. But an 009 distributor cannot provide any advance until AFTER the engine rpm starts to increase (the advance starts happening at around 1200-1300 rpm) so, if the carburettor is set to run a little lean (LESS fuel), you get stumbline or hesitation (a "flat spot") which usually means the driver has to blip the throttle a time or two to get the rpm up to the point where the 009 distributor is starting to advance, then "feather" the throttle (and slip the clutch) so the rpm stays high, to avoid that flat spot.
The most common technique to overcome the flat spot associated with the 009 distributor is to replace that "missing" advance with extra fuel - a larger main jet, maximum stroke on the accelerator pump, and in some cases filling in the air-bleed hole in the throttle butterfly. By running the engine richer than normal throughtout its operation, the flat spot is minimised.
The earlier Solex carburettors (28PCI, 28PICT and 30PICT/1 and /2) are set to run a little on the rich side (the VW engine actually likes around 13.8:1 air/fuel ratio, where the ideal is 14.5:1). So since these carburettors are set to run rich anyway, the flat spot is often not noticable, or can be tuned out with minor adjustments.
But in 1970/71 the emissions problem was becoming recognised, and VW changed the jetting on the 30PICT/3 (1970 US only) and the 34PICT/3, and /4 to run the carburettor leaner - closer to the ideal 14.5:1 air/fuel ratio (the California 34PICT/4 used especially lean jetting and a throttle positioner to ensure that the throttle closed slowly after you lifted your foot off the pedal). So with this leaner running carburettor set-up, the 009 distributor flat spot becomes a real issue.
You'll hear most complaints from folks who use the 34PICT/3, 34PICT/4 or the modern equivalent for the smaller carburettors - the Brosol H30/31 (which is almost identical to the 1970 30PICT/3) - all of which normally come with lean jetting.
Another issue with the 009 distributor is the limited maximum advance. The vacuum distributors can run up to a maximum of about 40-42 degrees under the right conditions (light throttle and medium speeds for example) and this helps fuel economy. But if you maintained that much advance with a full throttle and low/medium rpm, the engine would ping/detonate, a problem which can destroy an engine if not corrected. The reason is rather technical, but is mainly related to the amount of residual exhaust gases which are left in the cylinder compared to the incoming charge. There is always SOME residual gas, since there's a head space above the cylinder. At part throttle there is a proportionally larger amount of burned gases in comparison to the fresh stuff (throttled fresh mixture but same head space of burned gasses). At full throttle there's a lower proportion of burned gases because you are letting in MORE fresh mixture for the fixed volume of head space. This "contamination" of the fresh mixture alters the flame speed (the time it takes for the fuel/air mixture to burn) so open-throttle needs less advance (burns faster) and part-throttle needs more advance (burns slower) at any particular rpm.
Incidentally, this is part of the reason why the low compression 1200cc engines need more advance - usually 10BTDC compared to 7.5 BTDC for most 1500/1600cc engines. Low compression means more head space (compared to the cylinder volume), and so there is more contamination of the fresh charge throughout the rpm range, and that means a little more advance is needed so all the fuel is burned just as the piston starts it's descent.
There is an rpm-related issue, too. As the engine rpm increases, the spark needs to occur sooner (more advance) to make sure the maximum pressure on the piston occurs just as it starts its descent.
The vacuum distributor senses throttle position, so if you floor the throttle at low-medium speeds, the distributor is able to "back off" the advance until the engine speed catches up with the new throttle position (slowly allowing the extra advance back in as the rpm/airflow rises). The 009 distributor can't do this, so it HAS to be set to "worst case," which is a maximum advance of between 28 and 32 degrees at 2500-2600 rpm (which is why we set the 009 distributor at 3000rpm - to make sure that all the advance is present).
Since the 009 distributor has been limited to a maximum advance of 28-32 degrees compared to the vacuum distributor's maximum advance of 40-42 degrees, it's actually under-advanced for a lot of driving conditions, and this means worse fuel economy. And because you need to set the carburettor to run rich to reduce the flat spots, fuel economy suffers even more.
Because the 009 distributor is built very cheaply, the total amount of advance varies from one distributor to the next. This means that when setting the 009 distributor, it's important to set it at maximum rpm, not idle, since the maximum advance is much more important for most engine conditions. Always use as much of the maximum advance of 28-32 degrees as the engine can take without pining/detonating, as this will reduce any flat spots just a little, and also help fuel economy just a little. If it still pings at a maximum advance of 28 degrees, always use a higher octane fuel. NEVER use less than a maximum advance of 28 degrees because it means the engine is seriously under-advanced at higher rpm and will run hotter than it needs to, and fuel economy will suffer as well.
In the heavier-bodied Kombi/Bus and Karmann Ghia vehicles, you might need to limit the maximum advance to the 28-30 degree range. These engines are less likely to tolerate the 32 degree maximum advance, as they are driven with more throttle to accelerate the heavier body.
Once you have determined the maximum advance which works well for your 009 distributor, you can then measure the idle advance (which will probably be between 5 and 10 BTDC but might be outside that range). If you want to, you can then use THAT timing setting for THAT 009 distributor, set either at idle or statically.
So you can see that the 009 distributor is NOT ideal, but it will work. For best performance under all engine operating conditions, we recommend using a vacuum distributor.
Hope all that makes sense.
There are Tune-up Articles on our Web site which include info on both vacuum and 009 distributor settings.
* * * * *
bro,
wondering the 2nd pic u posted....looks powerful dude!!
was that engine sourced from porsche?heeh
wondering the 2nd pic u posted....looks powerful dude!!
was that engine sourced from porsche?heeh
Wow bro....................nice pictures & a lot of sharing.......well done.
FIVE STAR FOR YOU BROTHER VWMANIA..........................cheers
FIVE STAR FOR YOU BROTHER VWMANIA..........................cheers
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